JP2008233008A - Axle holding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a practical axle holding device capable of improving the detection accuracy for a load applied to a shaft 12. <P>SOLUTION: A columnar deformation section 24 is disposed in the axle holding device 20. The columnar deformation section 24 grips a sensor 74 with two rods 76 and 78. In the columnar deformation section 24, compression amount is varied by approach or separation between a rod support section 72 and an arm section 60, and the axial load of the columnar deformation section 24 is detected. While, when the rod support section 72 and the arm section 60 relatively displace in the direction orthogonal to the axial direction of the columnar deformation section 24, misalignment on the contact surface between the rods 76 and 78 and sensor 74 is prevented by bending of the columnar deformation section 24 in the shearing direction, and reduction of the detection accuracy is prevented. In this case, the compression amount of the columnar deformation section 24 does not vary, and the effect of the relative displacement in the shearing direction is avoidable. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a wheel shaft holding device including a load sensor that detects a load applied to a wheel shaft of a vehicle.

A wheel is attached to the wheel shaft, and the load applied to the wheel can be acquired by detecting the load applied to the wheel shaft. Patent Document 1 listed below describes a wheel shaft holding device that detects a load applied to the wheel shaft. The wheel shaft holding device includes an outer peripheral portion that is a supported body supported by the suspension device and an inner peripheral portion that has a bearing and rotatably holds the wheel shaft by a bridge portion that is a connecting body. Has been. And the load of the up-down direction and the front-back direction which are added to a wheel shaft is detected by detecting the relative displacement of the outer peripheral part and inner peripheral part in the direction orthogonal to a wheel shaft with a load sensor.
Japanese Patent Laid-Open No. 2004-360782

However, in the wheel shaft holding device of Patent Document 1, it has been found that the detection accuracy may be lowered even with a load in a range assumed in normal traveling. The reason is that not only the load in the vertical direction and the longitudinal direction is applied to the wheel shaft, but also a load that rotates the wheel shaft around an axis perpendicular to the wheel shaft may be applied. It is assumed that there is relative displacement in the direction. For example, the relative displacement in the axial direction causes a shift between the load sensor and the outer peripheral portion, and it is estimated that the shift causes a decrease in accuracy.
As in the above example, the conventional wheel shaft holding device still has room for improvement from the viewpoint of improving practicality, such as improving detection accuracy. The present invention has been made in view of such circumstances, and an object of the present invention is to obtain a more practical wheel shaft holding device.

  In order to solve the above problems, a wheel shaft holding device of the present invention includes a load sensor that detects a relative displacement in a specific direction between a supported body supported by a suspension device and a wheel shaft holding body that holds the wheel shaft, The columnar transmission body is provided with a columnar transmission body arranged in series with the load sensor in the specific direction, and the columnar transmission body is more elastically deformed than a cylinder having the same material and a length twice the diameter. It is characterized by being made easy to do.

In the wheel shaft holding device of the present invention, the detection accuracy of the load applied to the wheel is improved as compared with the conventional wheel shaft holding device.
In the conventional wheel shaft holding device, since the rigidity of the portion that holds the load sensor is excessive, it is estimated that one reason is that an appropriate load is not applied to the load sensor. On the other hand, the wheel shaft holding device of the present invention includes a columnar transmission body that is relatively easily elastically deformed, so that an appropriate load can be applied to the load sensor, which reduces the detection accuracy. Can be suppressed. That is, a more practical wheel shaft holding device can be obtained by the present invention.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the combinations of the constituent elements constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which some constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

  In the following paragraphs, (1) is in claim 1, (2) is in claim 2, (6) is in claim 3, (28) is in claim 4, (9) ) In claim 5, (10) in claim 6, (11) in claim 7, (12) in claim 8, (14) in claim 9, (17) ) Is equivalent to claim 10, the combination of (18) and (19) is equivalent to claim 11, (20) is equivalent to claim 12, and (24) is equivalent to claim 13. To do.

(1) a supported body supported by the suspension device;
A wheel shaft holder for holding the wheel shaft;
A connecting body for connecting the supported body and the wheel shaft holding body;
(a) a load sensor for detecting a load in a specific direction; (b) a columnar shape extending in the specific direction; and in series with the load sensor between the supported body and the wheel shaft holder in the specific direction. And a columnar transmission body that transmits at least part of the relative displacement between the supported body and the wheel shaft holder in the specific direction to the load sensor, and the columnar transmission body is made of the same material as the columnar transmission body. A wheel shaft holding device including one or more load detection devices that are more easily elastically deformed than a cylinder whose length is twice the diameter.
The wheel shaft holding device is supported by a suspension device and holds a wheel shaft to which a wheel is attached, and approaches and separates from the vehicle body together with the wheel. In other words, it is a part that transmits the load applied to the wheel axle (hereinafter referred to as “wheel axle load” unless otherwise required) to the suspension device. Can be detected. The direction in which the wheel and the vehicle body approach and separate from each other is referred to as “vertical direction in the vehicle” or simply “vertical direction”. Further, the traveling direction of the wheels is referred to as “front-rear direction in the vehicle” or simply “front-rear direction”.
The wheel shaft holder holds the wheel shaft in a rotatable or non-rotatable manner. That is, when the wheel is attached to the wheel shaft so as not to rotate relative to the wheel shaft, the wheel shaft is rotatably held via a bearing. When the wheel is attached to the wheel shaft rotatably relative to the wheel shaft, Is fixedly held. In any aspect, the wheel shaft holder receives the wheel shaft load.
The connecting body connects the supported body and the wheel shaft holding body and has moderate strength and elastic deformability. In order to detect the wheel axle load, it is necessary to allow an appropriate relative displacement between the supported body and the wheel axle holder. The relative displacement includes the relative displacement in the direction perpendicular to the axis of the wheel axis, the relative displacement in the axial direction of the wheel axis, and the relative rotation around the axis perpendicular to the axis of the wheel axis. And at least one determined by the arrangement of the load detection device.
The load sensor detects a load in a specific direction, and the load detection device includes a load sensor and a columnar transmission body arranged in series in the specific direction. When the load detection device is expanded and contracted in a specific direction in accordance with the relative displacement between the supported body and the wheel shaft holder, the load applied to the load sensor changes and the output of the load sensor changes. A load can be acquired based on the output. That is, in the load detection device, the relative displacement between the supported body and the wheel shaft holder in accordance with the wheel shaft load is converted into a change in the load applied to the load sensor, and the load is detected. The relative displacement amount between the supported body and the wheel shaft holding body is the relative displacement amount between the portion of the supported body that supports the load detection device and the portion of the wheel shaft support body that supports the load detection device. Since the output of the load sensor changes according to the relative displacement between the supported body and the wheel shaft holder, the load detection device is considered to detect the relative displacement amount between the supported body and the wheel shaft holder. You can also.
Note that the load sensor can measure a certain large load from the viewpoint of stably detecting the load. Furthermore, for example, it is desirable that it is 1/200 or more of the wheel axle load, and it may be 1/100 or more and 1/50 or more. For example, a ceramic sensor (described later), a piezoelectric sensor, or the like can be used as the load sensor.
By the way, there is a problem that the detection accuracy may decrease in the conventional wheel holding device. This is presumed to be partly because an appropriate load is not applied to the load sensor because the rigidity of the portion sandwiching the load sensor is excessive. For example, it is presumed that the detection accuracy is lowered when the elastic deformation cannot be appropriately performed according to the relative displacement between the supported body and the wheel shaft holder. On the other hand, since the load detection device of this section includes a columnar transmission body that is relatively easily elastically deformed, an appropriate load can be applied to the load sensor, thereby suppressing a decrease in detection accuracy. be able to. That is, according to the aspect of this section, a more practical wheel shaft holding device can be obtained.
The columnar transmission body is more easily elastically deformed than a cylinder having the same material and a length twice the diameter. The cylinder may have a length three times, five times, or seven times the diameter, and the larger the length-diameter ratio (length / diameter), the easier the elastic deformation. In addition, although the said cylinder is for contrast with a columnar transmission body and a cross-sectional shape is made into a perfect circle, it is not essential for a columnar transmission body to be a column shape. The cross-sectional shape of the columnar transmission body is not limited to a perfect circle, and may be various shapes such as an ellipse, a polygon, and an H shape. In addition, it is not essential that the cross-sectional shape and cross-sectional area of the columnar transmission body are uniform in the axial direction, and the cross-sectional area changes in the axial direction, such as a truncated cone shape, and the cross-sectional shape changes. can do. That is, any material can be used as long as it is more elastically deformed than the cylinder. Although the material which comprises a columnar transmission body is not specifically limited, For example, a metal thing can be used.
The columnar transmission body is rigid or elastically deformable enough to apply a stable load to the load sensor when it is appropriately elastically deformed according to the relative displacement between the supported body and the wheel shaft holder in a specific direction. It is desirable to have. In other words, the amount of compression of the columnar transmission body is appropriately changed according to the relative displacement in a specific direction, and the load applied to the load sensor is appropriately changed, so that the relative displacement between the supported body and the wheel shaft holding body is reduced. The part is transmitted to the load sensor.
Specifically, for example, in order to generate a relatively large load with a relatively small relative displacement, the columnar transmission body is made of a material having a Young's modulus (sometimes referred to as a longitudinal elastic modulus) of 50 GPa or more. In addition, it can be made larger, such as 90 GPa or more and 150 GPa or more. However, if the Young's modulus is too large, it becomes difficult to bend in the right-angle direction. Therefore, the Young's modulus of the columnar transmission body depends on other design matters, such as the dimensions (length, cross-sectional area) of the columnar transmission body, and the relative displacement in the specific direction and the perpendicular direction between the supported body and the wheel shaft holder. The maximum value is determined in consideration of the load resistance of the load sensor and the like.
The columnar transmission body can be formed of one member or a plurality of members. For example, a plurality of members can be arranged in series or in parallel. Furthermore, when arranging a plurality of members in series, the plurality of members can be arranged adjacent to each other, or a load sensor can be disposed between two of the plurality of members. Moreover, the columnar transmission body may be formed integrally with at least one of the supported body and the wheel shaft holding body.
(2) In the range where the columnar transmission body does not exceed the maximum load at least, the relative displacement between the supported body and the wheel shaft holding body in the direction perpendicular to the specific direction. Accordingly, the wheel shaft holding device according to (1), wherein the contact surface with the load sensor is elastically bent in the perpendicular direction without shifting from the load sensor.
First, the case where the relative displacement in the perpendicular direction between the supported body and the wheel shaft holder is adversely affected will be described as a factor that prevents an appropriate load from being applied to the load sensor.
As described above, the load sensor detects a load in a specific direction, that is, a certain direction, but it is difficult to limit the relative displacement between the supported body and the wheel shaft holder in one direction. It is inevitable to make a relative displacement in the direction perpendicular to the right angle. In that case, the load detecting device has its end on the supported body side and the end on the wheel shaft holding body side displaced in opposite directions in the perpendicular direction. That is, it receives a load in the shear direction. Since the detection accuracy tends to decrease due to the load in the shear direction, it is estimated that the detection accuracy decreases when the load sensor and the columnar transmission body are displaced on their contact surfaces. That is, if the rigidity in the shear direction is excessive, it is estimated that the detection accuracy is lowered.
On the other hand, the columnar transmission body of this section has a shearing rigidity that is small enough to prevent displacement at the contact surface between the load sensor and the columnar transmission body, that is, it is easy to bend in the perpendicular direction. From the viewpoint of preventing the occurrence of deviation in the contact surface between the load sensor and the columnar transmission body, it is possible to suppress a decrease in detection accuracy of the load sensor. That is, the aspect of this term is a more practical wheel shaft holding device.
Note that the relative displacement in the direction perpendicular to the supported body and the wheel shaft holder tends to increase when a moment is applied to the wheel shafts of the supported body and the wheel shaft holder. That is, the distance between the center line of the relative rotation between the supported body and the wheel shaft holding body and the connecting body is smaller than the distance between the center line of the relative rotation and the road surface (for example, 1/4 to 6 minutes). (About 1) is one factor. In other words, when turning, a load several times larger than the axial load acting on the ground contact portion of the wheel is applied to the connected body, which is simpler than when a load in the vertical (front / rear) direction is applied. This increases the burden on the connected body.
In many cases, both ends of the load detection device are relatively displaced in the perpendicular direction by the relative rotation between the supported body and the wheel shaft holder. For example, as described in detail in a later embodiment, in order to detect a load in the vertical direction, the front-rear direction, etc., when the load detection device is disposed with the vertical (front-rear) direction or the like as a specific direction, In many cases, both ends of the load detection device are relatively displaced in the direction perpendicular to each other by the relative rotation with the wheel shaft holder. The relative displacement amount is often larger than the displacement amount due to the relative movement of the supported body and the wheel shaft holder in the direction orthogonal to the wheel shaft. From such circumstances, it is important that the relative displacement in the shearing direction due to the relative rotation between the supported body and the wheel shaft holder can be followed by bending.
When the load sensor is sandwiched between, for example, one of the supported body and the wheel shaft holder and the columnar transmission body, the load sensor and the above-mentioned one are shifted at their contact surfaces. there is a possibility. However, the resistance force (friction force, adhesive force, etc.) against the displacement at the contact surface between the load sensor and the columnar transmission body is approximately the same as the resistance force of one of the load sensor, the supported body, and the wheel shaft holder. If it is the magnitude | size of this, the shift | offset | difference of a load sensor and said one can also be prevented by the ease of bending of a columnar transmission body.
The range in which the load applied to the wheel shaft does not exceed the maximum load can be, for example, a range of loads assumed in general traveling, and does not need to be assumed until the time of collision, the time of wheel removal, or the like. In other words, the rigidity in the shear direction of the columnar transmission body is set such that the load sensor and the columnar transmission body do not shift even when the assumed maximum load is applied to the wheel axle when the vehicle is running normally. It only has to be done.
Although the load sensor is slightly bent in the right-angled direction to a certain extent compared with the amount of deflection of the columnar transmission body, it is only necessary to prevent the deviation in consideration of the influence of the deflection and dimensions of the load sensor. In other words, in order to prevent a decrease in detection accuracy, it is sufficient that the entire load detection device can be bent to such an extent that a shift in the contact surface between the load sensor and the columnar transmission body can be prevented.
(3) In the range where the load applied to the wheel shaft does not exceed the maximum load at least, the columnar transmission body has a relative displacement between the supported body and the wheel shaft holder in a direction perpendicular to the specific direction. Accordingly, the wheel shaft holding device according to (1) or (2), wherein the wheel shaft is elastically bent in the right-angle direction by a force smaller than a resistance force against a deviation from the load sensor at a contact surface with the load sensor. apparatus.
In the aspect of this item, prevention of deviation is ensured because the columnar transmission body is bent relatively easily by a force smaller than the resistance force. The resistance to displacement is due to, for example, friction or adhesion.
(4) The columnar transmission body is disposed in series between the load sensor and the wheel shaft holder, and the support-side transmission body disposed in series between the load sensor and the supported body. The wheel shaft holding device according to any one of items (1) to (3), including at least one of the wheel-side transmission body.
The aspect of this section includes an aspect in which the columnar transmission body is disposed on one side of the load sensor and an aspect in which the columnar transmission body is disposed on both sides. In the aspect in which the columnar transmission body is disposed on one side of the load sensor, the structure is relatively simple. On the other hand, in a mode in which the columnar transmission body is disposed on both sides of the load sensor, the moment for peeling off the contact surface between the load sensor and the columnar transmission body is unlikely to be described later.
(5) The wheel shaft holding device according to (4), wherein at least one of the support-side transmission body and the wheel-side transmission body includes a plurality of support columns arranged in parallel in a state that can be separately deformed.
By configuring the support-side transmission body, etc., with a plurality of support columns, for example, with a single support column having the same cross-sectional area as the total cross-sectional area of the same material, length and cross-sectional shape. Compared with, it becomes easy to bend.

(6) The columnar transmission body has a maximum relative displacement amount between the supported body and the wheel shaft holding body in the perpendicular direction, and the maximum relative displacement amount between the supported body and the wheel shaft holding body in the specific direction. Even if it is larger than the relative displacement amount, the contact surface with the load sensor does not deviate from the load sensor according to the relative displacement between the supported body and the wheel shaft holder in the perpendicular direction. The wheel shaft holding device according to any one of (1) to (5), which is elastically bent in a right angle direction.
Depending on the configuration of the supported body, wheel shaft holder, and coupling body, the maximum relative displacement amount in the perpendicular direction between the supported body and the wheel shaft holder body may be larger than the maximum relative displacement amount in the specific direction. In such a case, it is effective to employ the columnar transmission body of this section. The maximum relative displacement amount can be a value assumed in general traveling, for example.
Further, the columnar transmission body does not deviate from the load sensor even if the maximum relative displacement amount in the perpendicular direction is 2 times or more, 5 times or more, 10 times or more than the maximum relative displacement amount in the specific direction. It is desirable that it bends elastically in the perpendicular direction.
(7) The deformation amount in the perpendicular direction when the columnar transmission body is subjected to a set load in a direction in which both end portions thereof are relatively displaced in the opposite direction in the perpendicular direction is such that the both end portions are in the axial direction. The wheel shaft holding device according to any one of (1) to (6), wherein the wheel shaft holding device is at least 10 times the amount of deformation in the axial direction when the set loads in directions of relative displacement in opposite directions are applied.
When a load having the same magnitude is applied, the displacement between the load sensor and the columnar transmission body is less likely to occur as the deformation in the perpendicular direction is easier than in the case of deformation in the axial direction of the columnar transmission body. It is desirable that the deformation amount in the perpendicular direction is as large as 20 times, 40 times, 80 times, or 160 times the deformation amount in the axial direction.
(8) The force (N) that the columnar transmission body elastically bends in the perpendicular direction in a state where the relative displacement amount in the perpendicular direction between the supported body and the wheel shaft holder is maximized. The wheel shaft holding device according to any one of (1) to (7), wherein a value obtained by dividing the relative displacement (mm) by a maximum value is 3000 N / mm or less.
The value (load-deflection ratio) obtained by dividing the force (N) to bend elastically in the perpendicular direction by the maximum value of the relative displacement (mm) may be 2000 N / mm or less and 1000 N / mm or less. desirable.
(9) At least one of the one or more load detection devices is provided with a separation prevention force that prevents the load sensor and the columnar transmission body from separating in the specific direction on their contact surfaces. And
In the range where the columnar transmission body does not exceed the maximum load at least, the maximum value of the bending stress acting on the end of the columnar transmission body when the columnar transmission body is bent in the perpendicular direction is the separation distance. The wheel shaft holding device according to any one of (1) to (8), wherein the wheel shaft holding device is smaller than a maximum value of the resistance bending stress that can be generated by the prevention force.
The aspect of this section adds a requirement for preventing peeling of the contact surface in addition to the requirement for bending. A bending moment acts on the columnar transmission body due to the relative displacement in the perpendicular direction between the supported body and the wheel shaft holder. Due to the bending moment, bending stress acts on the end of the columnar transmission body, causing one side portion of the neutral shaft to be pressed against the load sensor and causing the other side portion to be separated from the load sensor. On the other hand, a separation preventing force, which is a force that prevents separation of the contact surface between the load sensor and the columnar transmission body, is applied to the load detection device by a compressive load, an adhesive force, or the like. Therefore, if the resistance bending stress, which is the stress that resists the bending stress due to the separation preventing force, is greater than the maximum bending stress that pulls the end of the columnar transmitter away from the load sensor depending on the bending moment, the contact surface peels off. Can be prevented.

(10) The relative rotation center when at least one of the one or more load detection devices is rotated relative to the supported body and the wheel shaft holder by a moment in a direction orthogonal to the wheel shaft. The wheel shaft holding device according to any one of items (1) to (9), which is disposed along a plane including a line.
The following 7 items define the installation direction of the load detection device and the like.
In the load detection device, the wheel shaft load is acquired as a result of the amount of compression of the load detection device being changed by the relative displacement of the supported body and the wheel shaft holder in a specific direction. On the other hand, since the load detection device can bend in the perpendicular direction in the relative displacement in the perpendicular direction between the supported body and the wheel shaft holder, it follows the relative displacement in the perpendicular direction between the supported body and the wheel axle holder. And the amount of compression hardly changes depending on the relative displacement. That is, the load detection device can avoid the change in the compression amount due to the relative displacement in the perpendicular direction.
By using the above-described characteristics, it is possible to avoid a change in the compression amount due to the relative rotation between the supported body around the specific center line and the wheel shaft holder. That is, by arranging the load detection device along the plane, when the supported body and the wheel shaft holder rotate relative to each other, the load detection device bends in a right angle direction, thereby changing the compression amount due to the relative rotation. Can be avoided. In addition, since the rigidity of the coupling body is relatively large, the relative rotation between the supported body and the wheel shaft holding body is very small. For example, the relative rotation between the supported body and the wheel shaft holder often does not contribute to the acquisition of the wheel shaft load in the vertical direction and the front-rear direction. It is not preferable. Therefore, it is a great merit that the change of the compression amount due to the relative rotation can be avoided by the deflection of the columnar transmission body.
For example, when a moment is applied to raise one of the wheel shafts and lower the other, the supported body and the wheel shaft holding body are relatively rotated around the center line in the front-rear direction. By arranging the load detection device along a plane including the center line in the front-rear direction, when the supported body and the wheel shaft holder rotate relative to each other around the center line, the load detection device moves in a right angle direction. It is possible to avoid a change in the compression amount due to relative rotation by bending. In addition, disposing the load detection device along a certain plane means a state where the axis of the load detection device is included in a certain plane.
The relative rotation center line can be, for example, a straight line orthogonal to the wheel axis. Further, it is desirable that the relative rotation center line be the center of relative rotation when a moment is applied in a state where a load in a direction orthogonal to the axis of the wheel shaft is not applied.
(11) At least one of the one or more load detection devices is configured such that the supported body and the wheel shaft holding body are relative to each other by respective moments in two directions orthogonal to the wheel shaft and different from each other. The wheel shaft holding device according to any one of (1) to (10), which is disposed along a straight line passing through an intersection of two relative rotation center lines when rotated.
As described above, by arranging the load detection device along a plane including one relative rotation center line, it is possible to avoid a change in the compression amount due to the relative rotation around the one relative rotation center line. On the other hand, other relative rotation center lines pass through the intersection of the two relative rotation center lines. That is, the straight line passing through the intersection point is included on a plane including various relative rotation center lines. Therefore, by arranging the load detection device on a straight line passing through the intersection point, it is possible to avoid changes in the compression amount due to relative rotation around various relative rotation center lines. The two relative rotation center lines can intersect at a certain angle, and can be, for example, a straight line in the vertical direction and a straight line in the front-rear direction.
The specific direction of the load detection device can be a direction including at least one of a vertical component and a front-rear component in the vehicle, and can also be a direction including an axial component of the wheel shaft. it can.
(12) The wheel shaft according to any one of (1) to (10), wherein at least one of the one or more load detection devices is disposed along a plane orthogonal to the wheel shaft. Holding device.
The load detection device is often used to detect a load in at least one of the vertical direction and the front-rear direction of the vehicle. In that case, an aspect in which the load detection device is disposed on a plane orthogonal to the wheel axis as in the aspect of this section is particularly suitable. That is, since the wheel shaft is arranged in a direction not including the axial component, it is easy to detect a load in at least one of the vertical direction and the front-rear direction. If two load detection devices having different specific directions are arranged, the load in the vertical direction and the load in the front-rear direction can be acquired separately.
(13) At least one of the one or more load detection devices is disposed with the direction including a component in a direction parallel to the wheel shaft as the specific direction. The wheel shaft holding device according to any one of the above.
If the direction including the component in the direction parallel to the wheel axis is set as the specific direction, the load in the direction including the component in the axial direction of the wheel axis can be acquired.
(14) A direction in which at least one of the one or more load detection devices includes a direction including a component in a direction parallel to the wheel axis and at least one of a vertical direction and a front-rear direction in the vehicle. The wheel shaft holding device according to any one of (1) to (11), wherein the tilt direction is arranged as the specific direction.
According to the aspect of this section, it is possible to acquire a load in a direction including a component in a direction parallel to the wheel axis and at least one component in the vertical direction and the front-rear direction. It should be noted that when the aspect of this section is subordinate to the above section (10) or (11), it is particularly preferable because the change in the compression amount of the load detection device due to relative rotation can be avoided.
(15) The wheel shaft holding device includes a plurality of load detection devices as the one or more load detection devices,
Two of the plurality of load detection devices have different directions as the specific direction, are spaced apart from the wheel shaft in the radial direction, and are arranged along a plane parallel to the wheel shaft. The wheel shaft holding device according to item (14).
According to the aspect of this section, it is possible to separately acquire the load in the axial direction of the wheel shaft and one load in the vertical direction and the front-rear direction.
(16) The wheel shaft holding device includes a plurality of load detection devices as the one or more load detection devices,
Two of the plurality of load detection devices are the wheels according to any one of items (1) to (15), wherein planes orthogonal to the specific direction of each of them are arranged in directions orthogonal to each other. Axle holding device.
In the aspect of this section, the specific directions of the two load detection devices are perpendicular to each other. For example, one specific direction can be the up-down direction, and the other specific direction can be the front-back direction. The aspect of this section includes a case where the axes of the two load detection devices intersect each other at right angles and a case where the axes intersect at right angles (when they do not intersect).

(17) The supported body includes a plurality of attached portions that are disposed apart from each other and attached to a member provided in the suspension device;
The connecting body includes a plurality of bridge portions that connect each of the plurality of attached portions and the wheel shaft holding body,
Any one of the items (1) to (16), wherein each of the one or more load detection devices is disposed between each of the one or more of the plurality of attached portions and the wheel shaft holder. The wheel shaft holding device according to claim 1.
The mode of this section is a mode in which the supported body is supported by the suspension device at the plurality of mounted portions. By arranging a load detection device between the mounted portion and the wheel shaft holder, the amount of compression of the load detection device is effectively adjusted according to the relative displacement in a specific direction between the supported member and the wheel shaft holder. The wheel axle load can be acquired. For example, the wheel shaft holding device may be smaller than the inner diameter of the rim of the wheel. In this case, the wheel shaft holding device is relatively easily arranged.
In this aspect, the bridge portion connects the supported body and the wheel shaft holder along the direction including at least one of the vertical component and the front-rear component, and the axial direction of the wheel shaft. And a mode of connecting along a direction including at least one of a component in the vertical direction and a component in the front-rear direction and a component in the axial direction of the wheel shaft.
In the aspect of this section, the load detection device can be disposed on the outer periphery of the wheel shaft holder. That is, it can arrange | position on the larger periphery than the wheel-shaft holding body centering on a wheel shaft. In this case, it is easy to secure a space for arranging the load detection device on the outer periphery of the wheel shaft holder. In addition, the relative displacement amount resulting from the relative rotation of the supported body and the wheel shaft holder increases as the distance from the wheel shaft increases.
(18) Each of the plurality of attached portions is disposed radially away from the wheel shaft holder,
The wheel shaft holding device according to item (17), wherein the plurality of bridge portions connect each of the plurality of mounted portions and the wheel shaft holding body along a radial direction.
In this aspect, the plurality of attached portions support the wheel shaft holder from the outer peripheral side. In such a structure, for example, there is an advantage that the dimension of the wheel shaft holding device in the axial direction can be made compact. However, when the axial dimension of the bridge portion is relatively small, it is difficult to suppress the relative rotation between the supported body and the wheel shaft holder around the axis perpendicular to the wheel axis. In such a case, it is particularly preferable to avoid a change in the compression amount due to the relative rotation by bending the load detection device in a right angle direction.
(19) The wheel shaft holder is connected to the plurality of attached portions by the plurality of bridge portions, and two adjacent ones of the plurality of attached portions to the holder main body. A wheel side provided between the two and sandwiching and pressing one of the one or more load detection devices between one of the two attached portions adjacent to each other in the specific direction The wheel shaft holding device according to (17) or (18), including a pressing portion.
In the aspect of this section, the load detection device is disposed between two attached portions adjacent to each other. If it is between to-be-attached parts, it will be hard to interfere with a bridge | bridging part, and arrangement | positioning of a load detection apparatus will become comparatively easy. The wheel side pressing part can have, for example, an insertion hole into which the columnar transmission body is inserted, or a surface that contacts the columnar transmission body and the load sensor.
(20) Each of the plurality of attached portions is disposed on a circumference having a diameter larger than that of the holding body,
The wheel shaft holding device according to item (19), wherein the wheel side pressing portion is formed to protrude radially outward from the holding body main body.
By forming the wheel-side pressing portion to protrude radially outward from the holding body, for example, the distance between the wheel-side pressing portion and the attached portion can be appropriately adjusted. growing.
(21) The wheel shaft holding device according to (20), wherein the wheel-side pressing portion is arranged on the same plane as the plurality of attached portions.
According to the aspect of this section, the load detection device includes the relative rotation center line when the supported body and the wheel shaft holder are relatively rotated by the moment in the direction orthogonal to the wheel shaft, and is orthogonal to the wheel shaft. It can be arranged on a plane. The function and effect are the same as those in the above-mentioned items (10) and (11). This section shall not be subordinate to paragraphs (13) and (14) above.
(22) Two of the plurality of attached portions are arranged along one of a vertical direction and a front-rear direction in the vehicle,
The wheel-side pressing portion is formed to extend up to a straight line connecting the two attached portions, and one of the one or more load detection devices is arranged along one of the vertical direction and the front-rear direction. The wheel shaft holding device according to item (20) or (21), which is pressed.
According to the aspect of this section, the load detection device can be arranged along one of the vertical direction and the front-rear direction relatively easily, and one of the load in the vertical direction and the load in the front-rear direction is acquired. Can do.
(23) The wheel shaft holding device according to (19) or (20), wherein the wheel-side pressing portion is disposed apart from the two attached portions adjacent to each other in the wheel axis direction.
According to the aspect of this section, the load detection device can be arranged in the direction including the axial component of the wheel shaft. The function and effect are the same as those in the above-mentioned items (13) and (14). This section shall not be subordinate to the above section (12).
(24) The wheel side pressing portion is provided radially outward on the outer peripheral portion of the holding body main body,
The supported body is connected to two adjacent ones of the plurality of attached portions at both ends, and is opposed to the wheel-side pressing portion at an intermediate portion, and the one or more load detecting devices The wheel shaft holding device according to item (19), including a supported-side pressing portion that presses one of them to the wheel-side pressing portion side.
In the aspect of this section, the load detection device is sandwiched and pressed between the supported-side pressing portion and the wheel-side pressing portion. According to the aspect of this section, the load detection device can be disposed along the straight line passing through the “intersection of the two relative rotation center lines” relatively easily. In this case, the supported side pressing portion presses one of the one or more load detection devices inward in the radial direction with the wheel axis as the center.

(25) The resistance force is (a) a friction-based resistance force that is a force that depends on friction at a contact surface between the load sensor and the columnar transmission body; and (b) the load sensor and the columnar transmission body. The wheel shaft holding device according to any one of items (1) to (24), including at least one of an adhesion force-based resistance force that is a force that depends on a force for bonding to each other.
The frictional resistance includes, for example, a static friction coefficient on the contact surface of the one or more load detection devices and a load received by the one or more load detection devices sandwiched between the supported body and the wheel shaft holder. Multiply value.
(26) In the standard state, the one or more load detection devices are arranged in a pre-compressed state that is pre-compressed in the specific direction, and the load applied to the wheel shaft does not exceed the maximum load, The wheel shaft according to any one of (1) to (25), wherein one or more load detecting devices are sandwiched between the supported body and the wheel shaft holder and maintained in a compressed state. Holding device.
The mode of this section is arranged with a preload applied to the load detection device. The load applied to the load detection device increases or decreases depending on the relative displacement between the supported body and the wheel shaft holder, but in the aspect of this section, the load is compressed even if the amount of decrease in load is assumed to be the maximum value. The preload is set so that the state is maintained. Therefore, it is possible to detect the amount of decrease in the compression amount in the specific direction of the load detection device from the standard state. The standard state can be, for example, a state where the vehicle is stationary or a state where no load is applied to the wheel shaft.
In addition, even if the amount of compression in a specific direction of the load detection device is reduced due to the relative displacement between the supported body and the wheel shaft holder, the load sensor is applied to the load sensor as long as the load applied to the wheel shaft does not exceed the maximum load. It is desirable to apply a preload so that the minimum value of applied pressure is 10 MPa or more. In addition, a preload can be applied so that the minimum pressure value is 20 MPa, 40 MPa, 80 MPa, 120 MPa or more. When the preload is large, it is easy to prevent the load sensor and the columnar transmission body from shifting, but it is desirable to determine the load sensor considering the load resistance. The pressure applied to the load sensor acts as the separation preventing force. A value obtained by multiplying the pressure applied to the load sensor by the area of the cross section perpendicular to the specific direction of the load sensor is the load applied to the load sensor.
(27) The load sensor according to any one of (1) to (26), wherein the load sensor is a ceramic sensor formed by dispersing a material whose electromagnetic characteristics change due to strain in a high-strength ceramic material. Wheel axle holding device.
The high-strength ceramic material can be, for example, fine ceramics such as high-purity zirconia and alumina, and various additives added thereto. The electromagnetic characteristics can be, for example, electrical resistivity. Note that the phenomenon that electromagnetic characteristics change due to strain may be referred to as a piezoresistive effect. A material having a piezoresistance effect such as La _0.75 Sr _0.25 MnO ₃ can be used as the material whose electromagnetic characteristics change due to strain. In that case, the electrical resistivity changes as an electromagnetic characteristic. Since this ceramic sensor has a characteristic of not detecting a load in the shear direction, it has a feature that it is easy to detect a load in a specific direction.
(28) The columnar transmission body is applied to the load sensor in a state where the pressure applied to the load sensor in a standard state and the relative displacement between the supported body and the wheel shaft holder in the specific direction are maximized. The wheel shaft holding device according to any one of (1) to (27), wherein a difference from the applied pressure is 5 MPa or more.
The aspect of this term prescribes | regulates the rigidity of the axial direction of a columnar transmission body. The load can be stably detected by changing the pressure applied to the load sensor by a maximum of 5 MPa or more from the standard state by the relative displacement between the supported body and the wheel shaft holder. The columnar transmission body may have a pressure difference of 10 MPa or more, 20 MPa or more, 40 MPa or more, or 80 MPa or more. A value obtained by multiplying the pressure difference by the area of the load sensor (such as a cross-sectional area in a direction orthogonal to the specific direction) is a load difference applied to the load sensor.
The content of the standard state is the same as that in the aspect in which the columnar transmission body is pre-compressed.
(29) When a load is applied to the columnar transmission body in its axial direction, the value obtained by dividing the load by the amount of axial deformation is 10000 N / mm or more (1) to ( 28) The wheel shaft holding device according to any one of the above items.
According to the aspect of this section, the rigidity in the axial direction of the columnar transmission body can be made sufficient. Note that the columnar transmission body can have a value obtained by dividing the axial load by the axial deformation amount of 20000 N / mm or more, 40000 N / mm or more, or 80000 N / mm or more.

  Hereinafter, some embodiments of the present invention and modifications thereof will be described in detail with reference to the drawings. It should be noted that the present invention is by no means limited to the following examples, and in addition to the following examples, there are various types based on the knowledge of those skilled in the art including the aspects described in the above [Aspect of the Invention] section. It can implement in the various aspect which gave the change and improvement of these.

1, 2 and 3 are a front view and a side view of a wheel shaft holding device 10 which is an embodiment of the claimable invention. 2 is a cross-sectional view along AA in FIG. 1, FIG. 1 is a cross-sectional view along BB in FIG. 2, and FIG. 3 is a front view (partial cross-section). The wheel shaft holding device 10 is attached to the suspension device, and rotatably holds the shaft 12 serving as the wheel shaft. A hub 14 (FIG. 1) is provided on one end side of the shaft 12, and a hub bolt 16 for fastening a wheel of a wheel is attached to the hub 14.
1 and 3 are the vertical direction (Z-axis direction) and the horizontal direction (Y-axis direction) of the vehicle, respectively. Also, the vertical direction and the horizontal direction in FIG. 2 are the vertical direction (Z-axis direction) and the front-back direction (X-axis direction) of the vehicle, respectively.

The wheel shaft holding device 10 includes a cylindrical portion 20 (which is a kind of holding body) that has a generally cylindrical shape, and a plurality of supports that are formed to extend radially outward from the cylindrical portion 20 and support the cylindrical portion 20. 22 (FIG. 2), a plurality of relative displacement reflecting portions 24 that reflect the relative displacement between the cylindrical portion 20 and the plurality of supports 22, and the relative displacement reflected by the plurality of relative displacement reflecting portions 24. And a columnar deformable portion 26 to be deformed. The columnar deforming portion 26 includes a load sensor and detects a load applied to the shaft 12 based on the amount of compressive deformation. The cylindrical portion 20, the support body 22, and the relative displacement reflecting portion 24 are formed of a steel material that is a metal material.
The cylindrical portion 20 is configured to rotatably hold the shaft 12 via a ball bearing 30 that is a kind of bearing. The ball bearing 30 is a double-row angular ball bearing, and a plurality of bearing balls 32 (hereinafter abbreviated as “balls” unless otherwise specified) are arranged in two rows on the wheel side and the vehicle body side, respectively. Is held. Two outer raceway surfaces 34 of the ball bearing 30 are formed in a curved shape on the inner peripheral portion of the cylindrical portion 20. The outer raceway surfaces 34 prohibit the movement of the plurality of balls 32 toward the outer periphery and the movement in the direction in which the two rows of balls approach each other.
On the other hand, two inner raceway surfaces 40 of the ball bearing 30 are formed in a curved shape on the outer peripheral portion of the shaft 12. On the hub 14 side of the shaft 12, one inner raceway surface 40 is formed on the shaft body 42, and on the tip side of the shaft 12 (opposite side of the portion where the hub 14 is provided), the raceway surface forming ring 44. Thus, the other inner raceway surface 40 is formed. The raceway surface forming ring 44 is fixed by a shaft nut 46 that engages with a male screw formed at the tip of the shaft body 42. The two inner raceway surfaces 40 prohibit the movement of the plurality of balls 32 toward the inner peripheral side and the movement of the two rows of balls in directions away from each other.
Through the ball bearing 30 described above, the shaft 12 is held by the cylindrical portion 20 so as to be relatively rotatable and relatively unmovable. In addition, it is not indispensable that the raceway surfaces 34 and 40 of the ball bearing 30 are formed on the cylindrical portion 20 and the shaft 12, and a ball bearing having an outer ring and an inner ring on which raceway surfaces are formed may be employed.

The plurality of support bodies 22 (FIG. 2) is four in this embodiment, and each of the support bodies 22 is arranged at equal intervals in the circumferential direction on a circle centered on the axis of the shaft 12. Moreover, it extends in a direction intersecting the vertical direction and the front-rear direction, and is disposed symmetrically in the vertical direction and the front-rear direction. Since the four supports 22 have the same configuration as each other, a single one will be representatively described.
The support 22 includes a fastened portion 52 in which a bolt hole 50 is formed, and a spoke portion 54 that connects the fastened portion 52 and the cylindrical portion 20. The fastened portion 52 is a kind of attached portion, fastened to a support member provided in the suspension device, and supported by the suspension device. The spoke part 54 is a kind of bridge part, and the rigidity thereof is sized to appropriately displace the fastened part 52 and the cylindrical part 20 in accordance with the load applied to the shaft 12. The magnitude of the relative displacement is set such that the wheel axle load can be detected within a range in which the spoke portion 54 can be elastically deformed and no problem occurs in the running of the vehicle. Specifically, the relative displacement amount of the fastened portion 52 and the cylindrical portion 20 in a direction orthogonal to the shaft 12 (for example, the vertical direction and the front-rear direction) is about 3 μm to 20 μm, for example, 10 μm.
The cylindrical portion 20 is provided with a plurality of arm portions 60 (four in this embodiment) extending radially outward from the outer peripheral portion thereof. Each of the arm portions 60 is integrally displaced relative to the four fastened portions 52 when the cylindrical portion 20 is relatively displaced. Moreover, each arm part 60 is located in the center of the two adjacent ones of the four support bodies 22 in the circumferential direction. And the front-end | tip part of each arm part 60 is located in the position comparable as the edge part of the two adjacent support bodies 22 in the up-down direction or the front-back direction.

The plurality of relative displacement reflecting portions 24 (FIGS. 2 and 3) reflect the relative displacement between the fastened portion 52 and the cylindrical portion 20, and the axial direction of the shaft 12 between the fastened portion 52 and the cylindrical portion 20. The relative displacement due to relative movement in the direction orthogonal to the vertical direction (for example, the vertical direction and the front-rear direction) and the relative displacement due to relative rotation about the axis orthogonal to the axial direction of the shaft 12 are reflected. In the present embodiment, eight relative displacement reflecting units 24 are provided. They are arranged on a circumference larger in diameter than the cylindrical portion 20 centering on the shaft 12.
Each of the relative displacement reflecting portions 24 is provided with a columnar deformation portion 26 which is a kind of load detecting device. The four columnar deformation portions 26 </ b> Z that are positioned in front of and behind the cylindrical portion 20 and are arranged along the vertical direction (Z-axis direction) detect a vertical load applied to the shaft 12. That is, the vertical direction is the specific direction. On the other hand, the four columnar deformed portions 26X located on the upper side and the lower side of the cylindrical portion 20 and disposed along the left-right direction detect a load in the front-rear direction (X-axis direction). That is, the front-rear direction is the specific direction. Hereinafter, as described above, in order to indicate the load detection direction of the columnar deformable portion 26, a symbol (X, Z) may be added after the reference numeral. In addition, symbols (X, Z) corresponding to the columnar deformable portion 26 may be attached to other components such as the arm portion 60.

Since the eight relative displacement reflecting parts 24 and the columnar deforming part 26 have the same configuration, one is enlarged in FIG. 4 and will be described representatively. The relative displacement reflecting portion 24 includes a rod support portion 72 that supports one end side of the columnar deformable portion 26, and an arm portion 60 that supports the other end side of the columnar deformable portion 26.
The columnar deformable portion 26 is configured by arranging a ceramic sensor 74 as a load sensor, a support side rod 76 supported by the rod support portion 72, and an arm side rod 78 supported by the arm portion 60 in series. Yes. Although the two rods 76 and 78 will be described in detail later, the two rods 76 and 78 each have a cylindrical shape and are formed of a steel material that is a metal material. The columnar deformed portion 26 is sandwiched between the fastened portion 52 and the arm portion 60 and detects a load by receiving a compressive load. As described in detail later, the two rods 76 and 78 are used. By providing this, it is easy to bend in the perpendicular direction (shear direction) perpendicular to the axial direction.

FIG. 5 shows a ceramic sensor 74 (hereinafter abbreviated as “sensor” unless otherwise required). The sensor 74 is substantially the same as that described in Japanese Patent Laid-Open No. 2002-310813 and Patent Document 1, and is a material in which a pressure resistance effect material is dispersed in an electrically insulating ceramic material so as to be electrically connected continuously. And a two-layer insulating portion 82 made of an electrically insulating ceramic material sandwiching the pressure detecting portion 80. In addition, electrodes 84 are respectively disposed on the two side surfaces of the pressure sensing unit 80 facing away from each other, and conductive wires 86 are connected to the electrodes 84. In this example, ZrO ₂ with 12 mol% of CeO ₂ added is used as the electrically insulating ceramic material. Further, the pressure resistance effect material is a material whose electrical resistivity changes due to strain, and La _0.75 Sr _0.25 MnO ₃ is used.
The sensor 74 changes the electrical resistivity in accordance with the pressure received by the pressure sensing unit 80 from the two-layer insulating unit 82. Therefore, the direction in which the one-layer pressure sensing unit 80 and the two-layer insulating unit 82 are stacked is the load detection direction of the sensor 74 (a kind of the specific direction). Note that the dimensions, sensitivity, and the like of the sensor 74 are determined in consideration of the rigidity of the spoke portion 54 and the rigidity of the columnar deformable portion 26. The sensor 74 is configured to generate a displacement of about 1 μm when a pressure of 100 MPa is applied in the load detection direction.
The sensor 74 is arranged so that the axial direction of the support side rod 76 and the like is the load detection direction. In the two-layer insulating portion 82, the tip surface of the support side rod 76 and the arm side rod 78 are respectively provided. It is in surface contact with the tip surface. It should be noted that the two-layer insulating portion 82 can be bonded to the distal end surface of the support side rod 76 and the distal end surface of the arm side rod 78, respectively. As the adhesive, for example, a thermosetting sheet adhesive (epoxy system) can be used.

The arm part 60 is a kind of wheel side pressing part, and includes an arm main body 90 on the cylindrical part 20 side and a fixing member 92 fastened to the tip of the arm main body 90. A V-shaped groove 94 extending in a tangential direction of the circumference around the shaft 12 and having a V-shaped cross section is formed on the distal end surface of the arm body 90 and the surface of the fixing member 92 on the arm body 90 side. Is formed.
The two V-shaped grooves 94 of the arm main body 90 and the fixing member 92 are arranged so that the arm-side rod is fixed when the fixing member 92 is fastened to the arm main body 90 with the arm-side rod 78 sandwiched between the two V-shaped grooves 94. 78 is dimensioned to be firmly fixed. Note that the two V-shaped grooves 94 and the arm side rod 78 can be brazed (brazed or the like) by silver brazing or the like.
In the present embodiment, the two arm-side rods 78 of the two columnar deformable portions 26 adjacent to each other are formed as one continuous rod, but may be two separate rods.

The rod support portion 72 is a type of supported-side pressing portion, and includes a base body 100 provided on the fastened portion 52 so as to be positioned on an axis passing through the center of the two V-shaped grooves 94 of the arm portion 60. The base body 100 is provided with through holes 102 aligned with the axis of the two V-shaped grooves 94. The through hole 102 is disposed in a direction perpendicular to the radial direction in which the arm portion 60 extends. Further, the through hole 102 has a portion close to the arm portion 60 as a rod fitting portion 104 having a relatively small diameter, and a portion far from the arm portion 60 has a female screw hole portion 106 having a relatively large diameter. A bolt 108 that presses the base end portion of the support side rod 76 toward the arm portion 60 is screwed into the female screw hole portion 106. The bolt 108 is prevented from loosening by the nut 110.
Further, the bolt 108 is disposed in a standard state in which the bolt 108 is tightened until a preload set in the sensor 74 is applied. In the present embodiment, the standard state is a state where the vehicle is stationary (1G state), but may be another state. For example, a state where no load is applied to the shaft 12 can be set as a standard state.
Note that the base end portion of the support side rod 76 has a larger diameter than the tip end portion, and is tightly fitted to the rod fitting portion 104.

The operation will be described.
The wheel shaft holding device 10 mainly has a cylindrical portion 20 (arm portion 60) and a fastened portion 52 (rods) by elastically deforming the spoke portion 54 in accordance with a wheel shaft load that is a load applied to the shaft 12. It is configured to allow relative displacement with the support 72). As the amount of compressive deformation of the columnar deformable portion 26 is changed by the relative displacement between the arm portion 60 and the rod support portion 72 (hereinafter, abbreviated as “compressed amount” unless otherwise required), the sensor 74 The output signal changes and the load applied to the shaft 12 (or the load received by the sensor 74) can be acquired.
The wheel axle load is acquired by electrically connecting the sensor 74 to a wheel axle load obtaining device (not shown) via the conductive wire 86 and processing the output signal of the sensor 74 by the wheel axle load obtaining device. Made by. The wheel shaft load acquisition device may include, for example, an electric circuit such as a computer and an amplifier circuit.

Below, a specific example is given and demonstrated about the load which the sensor 74 receives when the cylindrical part 20 (arm part 60) and the to-be-fastened part 52 (rod support part 72) carry out relative displacement.
For example, when a wheel shaft load is applied to the shaft 12 so as to raise the shaft 12 such as when overcoming a bump on the road surface, the arm portion 60 is relatively lifted with respect to the fastened portion 52 together with the cylindrical portion 20. Be displaced.
In this case, the compression amount of the columnar deformation portion 26Z on the upper side of the two arm portions 60Z extending in the longitudinal direction of the vehicle is increased, and the compression amount of the columnar deformation portion 26Z on the lower side of the two arm portions 60Z is decreased. . That is, the load received by the upper sensor 74 increases and the load received by the lower sensor 74 decreases. Note that the absolute value of the increase amount of the load of the upper sensor 74 and the decrease amount of the load of the lower sensor 74 are equal. Since the upper and lower sensors 74 output a resistance value corresponding to the load, it is possible to acquire the wheel shaft load in the direction of increasing based on the output value. Note that the resistance value in the standard state is used as a reference, and the wheel axle load is acquired based on the amount of change in the output value from the reference value. Further, the amount of change in the output values of the upper sensor 74Z and the lower sensor 74Z is reversed between positive and negative.
In this example, the wheel shaft load in the vertical direction is detected by the four sensors 74Z, and the wheel shaft load can be obtained with high accuracy by obtaining the average load thereof. The wheel axle load can also be acquired by one or more of the four sensors 74Z.

Note that when the arm portion 60 is relatively displaced with respect to the fastened portion 52 in the upward and downward relative displacement reflecting portions 24 of the cylindrical portion 20, the columnar deformation portion 26 </ b> X that detects the load in the front-rear direction is detected. Both ends are relatively displaced in directions opposite to each other in a direction perpendicular to the axial direction, that is, in the shearing direction. At that time, the columnar deforming portion 26X bends in the shearing direction, so that a shift in the contact surface between the support side rod 76 and the like and the sensor 74 is prevented, and a decrease in detection accuracy is prevented. Further, the columnar deformation portion 26X does not increase or decrease the amount of compression in the load detection direction depending on the bending in the shearing direction, and does not affect the output of the sensor 74X. The rigidity of the columnar deformed portion 26X will be described in detail later.
Although the sensor 74 receives a load in the shear direction, the sensor 74 has a characteristic of not detecting the load in the shear direction, and therefore does not affect the output of the sensor 74X that detects the load in the front-rear direction. .
Note that a vertical moment may be applied to the shaft 12 due to wheel offset, which is the same as in the following description.

For example, when a vertical moment is applied to the shaft 12 such as when turning is performed, the cylindrical portion 20 is rotated relative to the fastened portion 52. The relative rotation center line that is the center line of the relative rotation becomes a front-rear center line (X) that is a straight line that passes through the center positions of the four fastened portions 52 and extends in the front-rear direction.
When the cylindrical portion 20 is rotated relative to the fastened portion 52 around the front-rear center line, the two arm portions 60X extending in the vertical direction are relatively displaced relative to the rod support portion 72 in the axial direction of the shaft 12. . At that time, as described above, the columnar deforming portion 26X bends in the shearing direction, so that the contact surface between the support-side rod 76 and the sensor 74 and the sensor 74 is prevented from being displaced, and a decrease in detection accuracy is avoided. Further, the amount of compression in the load detection direction of the columnar deformable portion 26X hardly changes. That is, in this embodiment, each columnar deformation portion 26X is disposed along a plane including the front and rear center lines, and a change in the compression amount due to relative rotation around the front and rear center lines is avoided. The sensor 74 receives a load in the shear direction, but does not affect the output of the sensor 74X that detects the load in the front-rear direction, as described above.
On the other hand, the two arm portions 60Z extending in the left-right direction are also relatively rotated. It is slight compared with the columnar deformed portion 26X. Therefore, as described above, the output of the sensor 74Z is not affected by the relative rotation.

Note that, for example, even when the load in the vertical direction and the load in the direction of relative rotation about the front and rear center line (X) are combined, the deflection of the columnar deformable portion 26Z and the characteristics of the load sensor 74Z are applied. Thus, the change in the compression amount due to the relative rotation is avoided, and the load in the vertical direction can be detected.
The case where a longitudinal load is applied to the shaft 12 and the case where a longitudinal moment is applied are the same as the case where the vertical load is applied to the shaft 12 and the case where a vertical moment is applied, respectively. Since there is, explanation is omitted.

In the present embodiment, the distance between the front / rear center line (X) and the spoke portion 54 is set to about one fifth of the distance between the front / rear center line and the road surface. Therefore, a load several times the lateral force input to the ground contact portion of the wheel is applied to the spoke portion 54 that receives a moment during turning. The spoke portion 54 connects the cylindrical portion 20 and the fastened portion 52 along the radial direction, and has a relatively small axial dimension. The relative displacement due to relative rotation is larger than the relative displacement toward. Under such circumstances, the load in the direction orthogonal to the axis of the shaft 12 can be easily detected by avoiding the change in the compression amount due to the relative rotation around the front and rear (up and down) axes.
Further, since it is possible to avoid a change in the compression amount due to relative rotation around the front and rear (up and down) axis, it is possible to measure the load with a small number of sensors.

  When a longitudinal moment is applied to the shaft 12, the relative rotation center line becomes a straight line extending in the vertical direction through the centers of the four fastened portions 52, that is, the vertical center line (Z). The intersection of the front-rear center line and the vertical center line is referred to as the center O. The center O is equidistant from the four fastened portions 52 and is located on the same plane as them. In the present embodiment, the center O is located on the axis of the shaft 12. The eight columnar deformation portions 26 are disposed along a plane that is orthogonal to the axis of the shaft 12 and passes through the center O.

As described above, in the wheel shaft holding device 10, even if the arm portion 60 and the fastened portion 52 are relatively displaced in a direction perpendicular to the load detection direction of the columnar deformable portion 26, the influence can be avoided. it can. However, conventionally, when the amount of relative displacement in the shear direction is large, there is a possibility that an adverse effect described later may occur.
Here, the wheel shaft load measurement result of the conventional wheel shaft holding device described in Patent Document 1 will be described. In FIG. 6, the hub 14 attached to the shaft 12 is increased after the wheel load on the upper side is increased to the assumed maximum load and then decreased, and then the wheel shaft load on the lower side is assumed to be the highest possible load. The change of the output value of the sensor 74 at the time of decreasing after making it increase to a load is shown typically. The load is input as an offset in both the vertical direction, and the supported body and the wheel shaft holder are relatively displaced in the vertical direction and are relatively rotated around the front-rear center line.
In this measurement result, elliptical hysteresis tends to occur in the output of the sensor 74. In addition, when the same measurement was performed with the maximum value of the wheel axle load sufficiently small, there was a tendency that hysteresis did not occur. When hysteresis occurs, the wheel axle load value corresponding to the output value of the sensor 74 is widened, and the detection accuracy is lowered. The cause of this hysteresis is presumed to be that some change occurred in the mounting state of the sensor 74 due to the relative displacement in the shear direction. Specifically, for example, it is assumed that the sensor and the outer peripheral portion (or the inner peripheral portion) are displaced at their contact surfaces due to the relative displacement in the shear direction, and the load applied to the sensor 74 changes.

  Therefore, in the present embodiment, in order to reduce the influence of the relative displacement in the shearing direction, the two rods 76 and 78 are provided as described above so that the columnar deformable portion 26 is relatively easily bent. The two rods 76 and 78 will be described in detail. It should be noted that the bending in the shearing direction is that a portion extending from the rod support portion 72 of the support side rod 76 (a kind of support side transmitting body) and a portion extending from the arm portion 60 of the arm side rod 78 (wheel side). Therefore, when the rods 76 and 78 (the support side rod 76 and the arm side rod 78) are described in the description of the bending and rigidity of the rods 76 and 78, the above-mentioned extension It shall refer to the part that has been taken out.

  The rigidity of the rods 76 and 78 when expanding and contracting in the axial direction satisfies the following relationship in this embodiment. That is, “the series rigidity of the rods 76, 78 and the sensor 74” and “the rigidity in the vertical (front / rear) direction between the fastened part 52 and the cylindrical part 20 (that is, the vertical (front / rear) direction of the four spoke parts 54). Ratio) ”is set to a set ratio. For example, the ratio can be set to “1:20”. In that case, a load that is 1/21 of the load in the vertical (front-rear) direction applied to the shaft 12 is applied to the sensor 74. The ratio can be changed as necessary. For example, when the load resistance is changed by changing the pressure receiving area of the sensor 74, the ratio is 1:10 to 1: 200. For example, the load received by the sensor 74 can be adjusted.

More specifically, the load is applied when the preload, which is a load applied to the load sensor 74 in the standard state, and the relative displacement in the vertical (front-rear) direction between the fastening portion 52 and the cylindrical portion 20 are maximized. The difference from the load applied to the sensor 74 is set to a value within the set range. The setting range can be, for example, a range (about ± 5%) including a load that is 1/21 of the maximum value of the wheel axle load. Here, when the maximum relative displacement amount in the vertical (front-rear) direction is Zm, and the rods 76 and 78 are each deformed in the axial direction by half of the maximum relative displacement amount Zm, the following relationship is obtained. In order to facilitate understanding, the sensor 74 is ignored.
Zm / 2 = Wa · L / (A · E) (1)
Wa is the maximum amount of increase in load applied to the rods 76 and 78, and L, A and E are the length, cross-sectional area and Young's modulus of the rods 76 and 78, respectively. Each element can be adjusted so that Wa becomes a value within the set range.

Described below is the bending rigidity in the direction perpendicular to the axial direction of the rods 76 and 78 (shear direction).
FIG. 7 schematically shows an exaggerated state where the columnar deformable portion 26 is bent in the shearing direction. In the present embodiment, the rods 76 and 78 are made of the same material and the same diameter, and are made uniform in diameter in the axial direction. Further, the length L of the portion extending from the rod support portion 72 of the support side rod 76 and the length L of the portion extending from the arm portion 60 of the arm side rod 78 are equal to each other. As a result, the bent shape of the support side rod 76 and the bent shape of the arm side rod 78 are equal to each other, and are point symmetric in the left-right direction of the drawing.
Therefore, assuming that the maximum amount of bending in the shearing direction is assumed to be δm, the amount of bending of the rods 76 and 78 is δm / 2 which is half of the maximum amount of bending δm. In order to facilitate understanding, the sensor 74 is ignored.
Here, assuming that the rods 76 and 78 are cantilever beams having a length L, the deflection amount δ thereof is obtained by the following equation.
δ = WL ³ / (3EI) (1-1)
W is the load in the shear direction, L is the length of the beam, E is the Young's modulus, and I is the moment of inertia of the cross section.
The bending amount “δm / 2” and the maximum load “Wm”, which is the load that maximizes the bending amount in the shearing direction, are substituted into the above equation (1-1) and solved for Wm.
δm / 2 = WmL ³ / (3EI) (1-2)
Wm = δm · (3EI / 2L ³ ) (1-3)
In the above equation (1-3), the meaning of the maximum load Wm in the shearing direction is a load necessary to bend the rods 76 and 78 by “δm / 2”. The maximum load Wm is caused by the resistance force R against the displacement of the contact surface between each of the rods 76 and 78 and the sensor 74. That is, if the load Wm is smaller than the resistance force R, the contact surfaces of the rods 76 and 78 and the sensor 74 do not deviate, and the columnar deformation portion 26 shears according to the relative displacement in the shear direction between the fastened portion 52 and the arm portion 60. It can bend in the direction. On the other hand, when the load Wm is equal to or greater than the resistance force R, the contact surfaces of the rods 76 and 78 and the sensor 74 may be displaced, leading to a decrease in load measurement accuracy. Therefore, the following equation is obtained.
R> Wm (1-4)

The resistance force R depends on the frictional force between each of the rods 76 and 78 and the sensor 74, and is expressed by the following equation.
R = μP (1-5)
Note that μ is a coefficient of static friction and P is a minimum compression load. The compressive load is set to the preload P0 in the standard state, but becomes smaller than the preload P0 when the arm portion 60 and the rod support portion 72 are relatively displaced in a direction away from each other. Therefore, the minimum compressive load P is set to the minimum size assumed as in the following equation.
P = P0−Ps (1-6)
P0 is the preload, and Ps is the maximum reduction amount of the assumed compressive load.
If the rods 76 and 78 and the sensor 74 are bonded, the resistance force R becomes the bonding strength in the shear direction.

In the present embodiment, the rods 76 and 78 satisfy the above conditions and reduce the influence of relative displacement in the shear direction. The above condition is a condition when the sensor 74 is ignored. However, since the condition is slightly more severe than the condition when the sensor 74 is considered, if the condition when the ignore is satisfied, The conditions when the sensor 74 is considered are also satisfied.
In the present embodiment, the sensor 74 is disposed at an equidistant position from the rod support portion 72 and the arm portion 60. That is, the bending allowance of the support side rod 76 and the bending allowance of the arm side rod 78 are made equal. Therefore, there is an advantage that bending stress that separates the contact surfaces of the rods 76 and 78 and the sensor 74 does not occur.

In consideration of the rigidity in the axial direction and the rigidity in the shearing direction, the following expression is obtained from Expression (1) and Expression (1-3).
(Δm / Zm) · (Wa / Wm) = L ² · A / (3I) (2-1)
Further, since the rods 76 and 78 have a cylindrical shape, the following expression is substituted into the expression (1-6).
^{A = πd 2/4, I} = πd 4/64 ··· (2-2)
(Δm / Zm) · (Wa / Wm) = 16L ² / (3d ² ) (2-3)
In the present embodiment, the maximum relative displacement amount δm in the shear direction in the relative displacement reflecting section 24 is about 20 times the maximum relative displacement amount Zm in the axial direction. Further, the maximum load Wa of the axial load applied to the columnar deformable portion 26 is set to be four times or more of the maximum load Wm in the shear direction. Therefore, the values of both sides of the formula (2-3) are 80 or more, and the following formula is obtained.
16L ² / (3d ² ) ≧ 80 (2-4)
L ≧ 3.9d (2-5)
That is, in the present embodiment, the length L of each of the rods 76 and 78 is 3.9 times the diameter d or more. Further, the length (2L) of the entire columnar transmission body is set to be 7.8 times or more of the diameter.

Assuming that Wa and Wm are equal using Expression (2-3), the following expression is obtained.
(Δ / Z) = 16L ² / (3d ² ) (2-6)
δ is the relative displacement in the shear direction, and Z is the relative displacement in the axial direction.
Substituting 3.9d for L in equation (2-6), the right side is approximately 81.
That is, in this embodiment, each of the rods 76 and 78 is a value obtained by dividing the deformation amount δ when the set load is applied in the shear direction by the deformation amount Z when the same set load is applied in the axial direction. A certain shear direction deflection ratio is 81 or more, which makes it very easy to bend.
In this embodiment, the rods 76 and 78 each have a shear direction displacement-load ratio of 1000 (N / mm) or less, which is a value obtained by dividing the resistance force R by the maximum relative displacement amount in the shear direction. Has been.
As a specific example, each of the rods 76 and 78 may have a length L of 9 mm (two 18 mm), a diameter d of 2 mm, and a Young's modulus E of 200 GPa. In this example, in the state where the maximum relative displacement amount δm in the shear direction is 200 μm (which is a larger estimated value), the resistance force R is sufficient to be 1.5 times the maximum load Wm in the shear direction. Has been enlarged to. The area of the sensor 74 is 4 mm ² and the resistance force R is about 100N.

An embodiment different from the above will be described.
In the above embodiment, the sensor 74 is sandwiched between the two rods 76 and 78. However, a rod as a columnar transmission body may be disposed on one side of the sensor 74.
8, 9, and 10 are a front view and a side view of a wheel shaft holding device 200 that is an embodiment of the claimable invention. 9 is a sectional view taken along the line AA in FIGS. 8 and 10, FIG. 8 is a sectional view taken along the line BB in FIG. 9, and FIG. 10 is a front view (partial section). Since the wheel shaft holding device 200 is configured in the same way as the wheel shaft holding device 10 of the above embodiment, the common components are denoted by the same reference numerals as those of the above embodiment, and the description thereof is omitted. The explanation will focus on the part. Since the operation of the wheel shaft holding device 200 is the same as that of the wheel shaft holding device 10, the description thereof is omitted.

The wheel shaft holding device 200 includes a plurality of relative displacement reflecting units 210 (eight in the present embodiment). One of them is shown enlarged in FIG. 11 and will be described representatively.
The relative displacement reflecting part 210 includes a columnar deforming part 220, a rod support part 72, and an arm part 222. The columnar deformable portion 220 is configured by arranging a ceramic sensor 230 as a load sensor and a columnar support side rod 232 supported by the rod support portion 72 in series.
The support side rod 232 has a cylindrical shape, is brought into surface contact with the insulating portion 82 of the sensor 230 at the distal end surface, and is press-fitted into the rod fitting portion 104 of the rod support portion 74 at the proximal end portion. In this embodiment, the support side rod 232 has a smaller diameter than that of the above embodiment. When the diameter of the rod is reduced, the rigidity is lowered and the elastic deformation is relatively easily made. Therefore, it is suitable when the load resistance of the sensor is small.
The ceramic sensor 230 (hereinafter abbreviated as “sensor” unless otherwise required) has the same structure as the sensor 74 of the above-described embodiment, and has a reduced size. In the sensor 230, each layer is disposed at the tip of the arm portion 222 in a direction orthogonal to the circumferential direction. Specifically, a recess 240 is formed in each of two side portions facing in the circumferential direction at the distal end portion of the arm portion 222, and the sensor 230 is formed on the recess wall surface 242 perpendicular to the circumferential direction of the recess 240. One of the two insulating layers 82 is in surface contact. In the present embodiment, the sensor 230 has a smaller pressure receiving area and a relatively lower load resistance than that of the above embodiment.

  About the rigidity at the time of extending-contracting in the axial direction of the support side rod 232, the relationship similar to the said Example shall be satisfy | filled (for example, said ratio is 1: 120 etc.). Further, if the length of the support side rod 232 is “2L”, the same formula as the formula (1) is established.

The bending rigidity in the right-angle direction (shear direction) perpendicular to the axial direction of the support side rod 232 will be described.
FIG. 12 schematically shows an exaggerated state where the columnar deformable portion 220 is bent in the shearing direction. The “support side rod 232” bends “the portion extending from the rod support portion 74”. Therefore, when the “support side rod 232” is described as the support side rod 232, the bend and rigidity are extended from the rod support portion 74. It shall refer to the part that was taken out.
In this embodiment, the portion of the support side rod 232 that extends from the rod support portion 74 has a uniform material and diameter in the axial direction. Therefore, assuming that the maximum relative displacement amount in the shearing direction is assumed to be δm, the support-side rod 232 has a half on the rod support portion 74 side and a half on the sensor 230 side, each half of the total relative displacement amount δm. It will be bent by “δm / 2”. Further, the bending shape on the rod support portion 74 side and the bending shape on the sensor 230 side are equal to each other, and are point-symmetric in the left-right direction in the figure.

  Here, when the half of the support side rod 232 is regarded as a cantilever having a length L, Expressions (1-1) to (1-6) of the above embodiment are established. In FIG. 12, the force for shifting the tip of the support side rod 232 and the sensor 230 on their contact surfaces is indicated by a broken white arrow. The magnitude of the force for shifting the contact surface is the same as the maximum load Wm.

The above conditions are from the viewpoint of preventing the displacement of the contact surface between the support side rod 232 and the sensor 230, and further, in this embodiment, as described below, the contact surface is prevented from peeling off. Conditions are also set from a viewpoint.
As shown in FIG. 13, the sensor side portion 250, which is a half of the support side rod 232 on the sensor 230 side, has a moment for rotating the sensor side portion 250 around the contact portion with the sensor 230 by the load Wm in the shear direction. Mw (following formula) is acting.
Mw = Wm · L (3-1)
Due to the moment Mw, a bending stress is generated, and a compressive stress σc that presses the end of the support side rod 232 against the sensor 230 and a tensile stress σt that separates are generated. Here, since the compressive stress σc is not a problem, the tensile stress σt will be described. The tensile stress σt is obtained by the following equation.
σt = Mw / Z = Wm · L / Z (3-2)
Z is a section modulus of the support side rod 232.
On the other hand, a compressive load P, which is a separation preventing force, acts on the support side rod 232 and the sensor 230. The stress σp (corresponding to the maximum value of the resistance bending stress) for pressing the end of the support side rod 232 against the sensor 230 by the compressive load P is obtained by the following equation.
σp = P / A (3-3)
If the compressive stress σp due to the compressive load P is larger than the tensile stress σt due to the moment Mw, peeling of the contact surface can be prevented.
σp> σt (3-4)

  In the present embodiment, the support side rod 232 satisfies the expressions (1-4) and (3-4). As a result, in all states where the relative displacement amount in the shear direction between the rod support portion 72 and the arm portion 222 is equal to or less than the assumed maximum relative displacement amount, the support side rod 232 does not deviate from the sensor 230 in the shear direction. The contact surface between the support-side rod 232 and the sensor 230 can be prevented from being bent.

In the present embodiment, the support side rod 232 also satisfies the expressions (2-1) to (2-3) and (2-6). In addition, the expressions (2-4) and (2-5) satisfy the same relationship although there are differences in the values of the maximum load (Wa, Wm) and the like. (2L) is about 7.8 times the diameter or more. Furthermore, in this embodiment, the bending ratio in the shear direction is 81 or more, which makes it very easy to bend. Furthermore, in this embodiment, the shear direction displacement-load ratio is 500 (N / mm) or less.
As a specific example, the support side rod 232 may have a total length 2L of 24 mm, a diameter d of 1 mm, and a Young's modulus E of 200 GPa. In this example, in the state where the maximum relative displacement amount δm in the shearing direction is 100 μm, the maximum value σp of the resistance bending stress due to the force that prevents the contact surfaces from separating is sufficiently 1.5 times the bending stress σt. Has been enlarged to. The sensor 230 has an area of 1 mm ² and a minimum compressive load of about 150 N.

Another embodiment (inclined arrangement type) different from the above will be described.
In the above two embodiments, the columnar deformed portion is disposed on a plane orthogonal to the axis of the shaft 12. That is, the direction (X or Z) not including the component in the axial direction (Y) of the shaft 12 is the pressure sensing direction as the specific direction of the ceramic sensor.
On the other hand, in the present embodiment, the columnar deformed portion is disposed so as to be inclined with respect to the axis of the shaft 12. That is, the direction including the component in the axial direction (Y) of the shaft 12 and the component in the vertical direction (Z) or the front-rear direction (X) is the pressure sensing direction that is a specific direction of the ceramic sensor. Therefore, the relative displacement between the cylindrical portion 20 and the fastened portion 52 in the axial direction (Y) of the shaft 12 can be detected. That is, the wheel shaft load in the axial direction (Y) can be detected.

  14 and 15 are a front sectional view and a front view (partial cross section) of a wheel shaft holding device 300 which is an embodiment of the claimable invention. Since the wheel shaft holding device 300 is configured in the same way as the wheel shaft holding device 10 of the above embodiment, the same reference numerals as those of the above embodiment are attached to the common components, and the description thereof is omitted. The explanation will focus on the part.

In the present embodiment, the wheel shaft holding device 300 includes a plurality of relative displacement reflecting portions 310 (eight in the present embodiment) (FIG. 15). One of them is shown enlarged in FIGS. 16 and 17 and will be described as a representative.
The relative displacement reflecting part 310 includes a columnar deforming part 320, a rod support part 322, and an arm part 324. The columnar deforming portion 320 includes a ceramic sensor 330 as a load sensor, a columnar support side rod 334 supported by the rod support portion 322, and a columnar arm side rod 336 supported by the arm portion 324 in series. It is installed and configured. The ceramic sensor 330 (hereinafter abbreviated as “sensor” unless otherwise required) is the same as the sensor 74 of the above embodiment.

  The arm part 324 is a kind of wheel-side pressing part, and is located at the center of the two support bodies 22 adjacent to each other, and extends radially outward from the cylindrical part 20. Further, the thickness of the arm portion 324 in the axial direction is larger than that of the support body 22, and the arm portion 324 is disposed so as to protrude from the support body 22 toward the hub 14. A rod receiving portion 340 protruding in the circumferential direction is provided on the outer peripheral portion of the protruding portion. The rod receiving portion 340 is provided with a rod insertion hole 342 that is tightly fitted to the end of the arm side rod 336, and the arm side rod 336 is inserted into the rod insertion hole 342.

The rod support portion 322 includes a base body 350 that is provided on the outer peripheral portion of the fastened portion 52 and is erected in the same direction as the arm portion 324 extends. The base body 350 is provided with a through hole 352 arranged on the same axis as the rod insertion hole 342 of the rod receiving portion 340 and having a diameter larger than that of the rod insertion hole 342. A cylindrical holder 354 that holds the support side rod 334 is press-fitted into the through hole 352. The holder 354 is provided with a rod insertion hole 356 that is tightly fitted to the end of the support side rod 334, and the support side rod 334 is inserted into the rod insertion hole 356.
When the holder 354 is press-fitted into the through hole 352, the amount of insertion of the holder 354 is adjusted so that the preload applied to the columnar deformable portion 320 is within a set range.

As described above, in the present embodiment, the columnar deformable portion 320 is disposed to be inclined in the axial direction (Y axis) of the shaft 12. Specifically, for the four relative displacement reflecting portions 310Z provided on the left and right sides of the cylindrical portion 20, the columnar deformable portion 320Z has two components, an axial direction (Y-axis) and a vertical direction (Z-axis). Is arranged. The four columnar deforming portions 320Z have the same inclination angle (for example, about 45 degrees) with the axis.
Further, in each of the left side and the right side, the two columnar deforming portions 320Z are spaced apart from the axis of the shaft 12 in the radial direction, and are disposed along one plane parallel to the axis. Specifically, the arm portion 324 is disposed along a plane parallel to the axis (Y-axis) and the vertical direction (Z-axis) through the tip portion. In one plane, the two columnar deforming portions 320Z are arranged in a direction intersecting at right angles to each other.
The same applies to the four relative displacement reflecting portions 310X provided above and below the cylindrical portion 20. In the description of the four relative displacement reflecting portions 310Z, the vertical direction (Z axis) is read as the front and rear direction (X axis). I will do it.

The operation will be described.
18 to 20 schematically show the displacement of the upper one of the two columnar deforming portions 320 </ b> Z provided in the front-rear direction of the cylindrical portion 20. In addition, a change in the compression amount of the lower columnar deformable portion 320Z is also shown for reference. Note that an angle formed by the columnar deformable portion 320Z and the horizontal plane, that is, an inclination angle is defined as θ.
When the arm portion 324 is raised by Za relative to the rod support portion 322 (FIG. 18), the change in the compression amount of the columnar deformable portion 320Z is “Za · sin θ”. Note that the compression amount of the upper columnar deformable portion 320Z increases and thus changes positive, and the compression amount of the lower columnar deformable portion 320Z decreases and negatively changes. Further, the component in the shear direction (Za · cos θ) acts so as to bend the columnar deformable portion 320Z in the shear direction, and hardly affects the change in the compression amount in the load detection direction.
When the arm portion 324 is moved closer to the rod support portion 322 in the axial direction of the shaft 12 (FIG. 19), the change in the compression amount of the columnar deformable portion 320Z becomes “Ya · cos θ”. In addition, since the amount of compression of the upper and lower columnar deforming portions 320Z increases, the upper and lower sides are positively changed.
When the cylindrical portion 20 is rotated by α radians around the front-rear center line (X) with respect to the fastened portion 52 (FIG. 20), the distance from the front-rear center line to the tip of the columnar deformable portion 320Z is J. The displacement Qx of the tip is α · J. Since the tip end portion of the columnar deformable portion 320Z is displaced substantially in the axial direction, the change in the compression amount of the columnar deformable portion 320Z is equal to Qx. The upper columnar deformed portion 320Z has a positive change, and the lower columnar deformed portion 320Z has a negative change.
Further, the amount of compression of the columnar deforming portion 320X disposed above and below the cylindrical portion 20 is also changed by relative rotation around the front and rear center line (X). Here, the distance from the front-rear center line to the tip of the columnar deformable portion 320X is C times J, that is, CJ. Further, an angle formed by a straight line connecting the front and rear center line and the tip of the columnar deformable portion 320X and the axis of the shaft 12 is β. The displacement of the tip of the columnar deforming portion 320X is α · CJ, and Yx, which is the axial component of the displacement, is α · CJ · sinβ. The change in the compression amount of the columnar deformed portion 320X due to the axial component Yx is “Yx · cos θ”.
The case where the cylindrical portion 20 is relatively rotated around the vertical center line (Z) with respect to the fastened portion 52 is considered the same as the case where the cylindrical portion 20 is relatively rotated around the longitudinal center line (X). That is, the displacement Qz of the tip end portion of the columnar deformable portion 320X becomes equal to the change in the compression amount. In addition, the amount of compression of the columnar deforming portion 320Z disposed before and after the cylindrical portion 20 is also changed by the relative rotation around the vertical center line. The change in the compression amount of the columnar deformable portion 320Z is “Yz · cos θ”.

Based on the relationship described above, changes Uz _{1 to} Ux _{4 in} compression amounts of the eight columnar deformable portions 320 schematically shown in FIG. 21 are expressed by the following equations.
Uz ₁ = Za · sinθ + Qx + Ya · cosθ + Yz · cosθ (4-1)
Uz ₂ = −Za · sin θ−Qx + Ya · cos θ + Yz · cos θ (4-2)
Uz ₃ = Za · sinθ + Qx + Ya · cosθ−Yz · cosθ (4-3)
Uz ₄ = −Za · sin θ−Qx + Ya · cos θ−Yz · cos θ (4-4)
Ux ₁ = Xa · sinθ + Qz + Ya · cosθ + Yx · cosθ (4-5)
Ux ₂ = −Xa · sin θ−Qz + Ya · cos θ + Yx · cos θ (4-6)
Ux ₃ = Xa · sinθ + Qz + Ya · cosθ−Yx · cosθ (4-7)
Ux ₄ = −Xa · sin θ−Qz + Ya · cos θ−Yx · cos θ (4-8)

In addition, the axial component Yx of the displacement of the tip of the columnar deformable portion 320X at the time of relative rotation around the front-rear center line is α · CJ · sinβ, where α · J is the displacement Qx of the tip of the columnar deformable portion 320X. Therefore, the following equation is obtained.
Yx = Qx · C · sinβ (4-9)
When C · sin β is γ, the following equation is obtained.
Yx = γQx (4-10)
Similarly, the axial component Yz of the displacement of the tip of the columnar deformable portion 320Z during relative rotation around the vertical center line is also expressed by the following equation.
Yz = γQz (4-11)

The expressions (4-10) and (4-11) are substituted into the expressions (4-1) to (4-8).
Uz ₁ = Za · sinθ + Qx + Ya · cosθ + γQz · cosθ (5-1)
Uz ₂ = −Za · sin θ−Qx + Ya · cos θ + γQz · cos θ (5-2)
Uz ₃ = Za · sinθ + Qx + Ya · cosθ−γQz · cosθ (5-3)
Uz ₄ = −Za · sin θ−Qx + Ya · cos θ−γQz · cos θ (5-4)
Ux ₁ = Xa · sinθ + Qz + Ya · cosθ + γQx · cosθ (5-5)
Ux ₂ = −Xa · sin θ−Qz + Ya · cos θ + γQx · cos θ (5-6)
Ux ₃ = Xa · sinθ + Qz + Ya · cosθ−γQx · cosθ (5-7)
Ux ₄ = −Xa · sin θ−Qz + Ya · cos θ−γQx · cos θ (5-8)

Based on Expressions (5-1) to (5-8), Za, Xa, and Ya are obtained.
Za = (Uz ₁ −Uz ₂ + Uz ₃ −Uz ₄ ) / (4sinθ) − (Ux ₁ + Ux ₂ −Ux ₃ −Ux ₄ ) / (4γsinθ · cosθ) (5-9)
Xa = (Ux ₁ −Ux ₂ + Ux ₃ −Ux ₄ ) / ( ₄ sin θ) − (Uz ₁ + Uz ₂ −Uz ₃ −Uz ₄ ) / (4γsin θ · ₄ cos θ) (5-10)
Ya = (Uz ₁ + Uz ₂ + Uz ₃ + Uz ₄ + Ux ₁ + Ux ₂ + Ux ₃ + Ux ₄ ) / (8 cos θ) (5-11)

  The wheel shaft load acquisition device (not shown) acquires the change U of each compression amount based on the outputs of the eight columnar deformation portions 320, and based on the equations (5-9) to (5-11), Relative displacement amounts Za, Xa, Ya can be obtained. Since the change U in the compression amount of the columnar deformable portion 320 is equivalent to the change in the load applied to the sensor 330, the load applied to the sensor 330 is acquired from the output of the sensor 330, and the wheel shaft load is increased or decreased from the load. It is also possible to acquire components in the direction, the front-rear direction, and the axial direction.

Another embodiment (axial orthogonal type) different from the above will be described.
In all the embodiments described above, the columnar deformed portion was disposed on a straight line that three-dimensionally intersects the axis of the shaft 12. On the other hand, the columnar deformable portion may be disposed on a straight line that intersects (for example, orthogonally) the axis of the shaft 12.
22 and 23 show a front view and a side view of a wheel shaft holding device 400 which is an embodiment of the claimable invention. 23 is a sectional view taken along the line AA in FIG. 22, and FIG. 22 is a sectional view taken along the line BB in FIG. Since the wheel shaft holding device 400 is configured in the same way as the wheel shaft holding device 10 of the above embodiment, the same reference numerals are used for the common components and the description thereof is omitted, and is different. The explanation will focus on the part.

In the present embodiment, the wheel shaft holding device 10 includes a cylindrical portion 20 (which is a kind of holding body) that is generally cylindrical, and a rectangular or circular flange portion 410 that extends from the cylindrical portion 20 to the outer peripheral side. . The cylindrical portion 20 and the flange portion 410 are formed of a steel material that is a metal material.
The flange portion 410 has a flat cross-sectional shape that is elongated along the outer periphery of the cylindrical portion 20, and a plurality of flat holes 414 that penetrate the flange portion 410 in the axial direction of the shaft 12 are formed. In the present embodiment, four flat holes 414 are provided on the upper and lower sides and the front and rear sides of the cylindrical portion 20, and are arranged at equal intervals on a circumference around the axis of the shaft 12. . By these four flat holes 414, the flange portion 410 is roughly partitioned into an outer peripheral portion 412 and an inner peripheral portion 413.

In the flange portion 410, four portions sandwiched between two flat holes 414 adjacent to each other are defined as spoke portions 416, and the outer peripheral portion and the inner peripheral portion are connected with appropriate rigidity by the spoke portions 416. Yes. A radially outer portion of each spoke portion 416 is a fastened portion 418 in which a bolt hole 50 is formed, and each fastened portion 418 is fastened and supported by a member provided in the suspension device. The relative displacement amount between the fastened portion 418 and the cylindrical portion 20 in the direction orthogonal to the shaft 12 (for example, the vertical direction and the front-rear direction) is about 3 μm to 20 μm, for example, 10 μm.
The main spoke portion 416 and the spoke portion 54 have substantially the same rigidity.

A relative displacement reflecting portion 419 that reflects the relative displacement between the outer peripheral portion 412 and the inner peripheral portion 413 is provided in a portion where the flat hole 414 of the flange portion 410 is formed. In the present embodiment, there are four relative displacement reflecting portions 419, and each of the four to-be-fastened portions 418 is disposed between adjacent ones. Since these four relative displacement reflecting portions 419 have the same configuration, one is enlarged and shown in FIG. 24 as a representative example. FIG. 24 is a part of the CC cross section of FIG.
The relative displacement reflecting portion 419 includes a columnar columnar deformable portion 420 that is sandwiched between the outer peripheral portion 412 and the inner peripheral portion 413 of the flange portion 410 and receives a compressive load, and an end portion on the radially outer side of the columnar deformable portion 420. And a wheel side support portion 424 provided on a wall portion on the inner peripheral side of the flat hole 414 and supporting an end portion on the radially inner side of the columnar deformable portion 420. The columnar deformation portion 420 includes a ceramic sensor 430 as a load sensor, a columnar support side rod 434 supported by the rod support portion 422, and a columnar inner periphery supported by a wall portion on the inner periphery side of the flat hole 414. A side rod 436 is arranged in series. The ceramic sensor 430 (hereinafter abbreviated as “sensor” unless otherwise required) is the same as the sensor 74 of the above embodiment. The rods 434 and 436 are the same as the rods 76 and 78 of the above embodiment.

The rod support part 422 is a kind of supported side pressing part, and is a part on the outer peripheral side of the flat hole 414, and includes a base body 440 connected to two fastened parts 418. The base body 440 is provided with a through hole 442 that penetrates the center of the base body 440 in the radial direction of a circle centering on the axis of the shaft 12. A cylindrical holder 450 that holds the support side rod 434 is press-fitted into the through hole 442. The holder 450 is provided with an insertion hole 452 for inserting the support side rod 434. The insertion hole 452 is a bendable portion 454 that has a larger diameter at the cylindrical portion 20 side and allows the columnar deformable portion 420 to bend in a direction perpendicular to the axial direction. Further, the back portion of the insertion hole 452 is a rod insertion portion 456 that is tightly fitted to the end portion of the support side rod 434, and the end portion of the support side rod 434 is inserted into the rod insertion portion 456. . When the holder 450 is press-fitted into the through hole 442, the insertion amount of the holder 450 is adjusted so that the preload applied to the columnar deformable portion 420 has a size within a set range.
The wheel-side support portion 424 is a kind of wheel-side pressing portion, and includes a rod insertion hole 460 that is tightly fitted to an end portion of the inner peripheral side rod 436 provided on the inner peripheral side wall portion of the flat hole 414. The end of the inner peripheral side rod 436 is inserted into the rod insertion hole 460.

  The columnar deforming portion 420 is disposed orthogonal to the axis of the shaft 12 in the relative displacement reflecting portion 419. That is, the columnar deforming portion 420 is disposed with the direction perpendicular to the axis of the shaft 12 as the specific direction. Further, the columnar deforming portion 420 is disposed along a plane that is orthogonal to the axis of the shaft 12 and passes through the centers of the four spoke portions 416. Therefore, the columnar deformable portion 420 has two relative rotation center lines when the cylindrical portion 20 and the base body 440 are relatively rotated by each of moments in directions different from each other (for example, the vertical direction and the front-back direction). Are arranged along a straight line passing through the center O which is the intersection of the two.

The operation will be described.
The wheel shaft holding device 400 is configured to allow a slight relative displacement between the cylindrical portion 20 and the base body 440 by mainly deforming the spoke portion 416 in accordance with the load applied to the shaft 12. . As the amount of compressive deformation of the columnar deformable portion 420 is changed by the relative displacement between the cylindrical portion 20 and the base 440 (hereinafter, abbreviated as “compressed amount” unless otherwise required), the output signal of the sensor 430 is changed. Changes, and the load applied to the shaft 12 can be acquired. Note that the load applied to the shaft 12 is acquired by, for example, processing the output signal of the sensor 430 with the above-described wheel shaft load acquisition device or the like (not shown).

Below, a specific example is given and demonstrated about the load which the sensor 430 receives when the cylindrical part 20 and the base | substrate 440 carry out relative displacement.
For example, when a load is applied to the shaft 12 so as to raise the shaft 12 such as when overcoming a bump on the road surface, the cylindrical portion 20 is relatively displaced so as to rise with respect to the fastened portion 52. In this case, the compression amount of the columnar deformation portion 420Z on the upper side of the cylindrical portion 20 is increased, and the compression amount of the columnar deformation portion 420Z on the lower side of the cylindrical portion 20 is decreased. That is, the load received by the upper sensor 430 increases and the load received by the lower sensor 430 decreases. The absolute value of the increase amount of the load of the upper sensor 430 and the decrease amount of the load of the lower sensor 430 are equal. Since the upper and lower sensors 430 indicate an output value corresponding to the load, the load in the direction in which the shaft 12 is raised can be acquired based on the output value.
In this example, the load in the vertical direction is detected by the two sensors 430, and the load can be obtained with high accuracy by obtaining an average value thereof. Note that the load can be acquired by one of the two sensors 430.

In addition, when the cylindrical portion 20 is relatively displaced with respect to the fastened portion 52, the columnar deformable portion that detects the load in the front-rear direction in the relative displacement reflecting portion 419X positioned in the front-rear direction of the cylindrical portion 20. Both ends of 420X are relatively displaced in directions opposite to each other in a direction perpendicular to the axial direction, that is, in the shearing direction. At that time, the columnar deforming portion 420X bends in the shearing direction, so that a shift in the contact surface between the support side rod 76 and the like and the sensor 74 is prevented, and a decrease in detection accuracy is prevented. Further, the columnar deforming portion 420X does not increase or decrease the amount of compression in the load detection direction depending on the bending in the shearing direction, and does not affect the output of the sensor 430X.
Although the sensor 430 receives a load in the shear direction, the sensor 430 has a characteristic that it does not detect the load in the shear direction, and therefore does not affect the output of the sensor 430X that detects the load in the front-rear direction. .
Note that a vertical moment may be applied to the shaft 12 due to wheel offset, which is the same as in the following description.

For example, when a vertical moment is applied to the shaft 12 such as when turning is performed, the cylindrical portion 20 is rotated relative to the fastened portion 52. The relative rotation center line that is the center line of the relative rotation is a front-rear center line (X) that is a straight line that passes through the centers of the four fastened portions 52 and extends in the front-rear direction.
When the cylindrical part 20 is rotated relative to the fastened part 52 around the front-rear center line, the rod support part 422 and the wheel-side support part 424 are moved in the axial direction of the shaft 12 in the upper and lower relative displacement reflecting parts 419Z. Relative displacement. At that time, as described above, the columnar deforming portion 420Z bends in the shearing direction, so that a shift in the contact surface between the support side rod 434 and the sensor 430 is prevented, and a decrease in detection accuracy is avoided. Further, the amount of compression in the load detection direction of the columnar deformable portion 420Z hardly changes. That is, in this embodiment, each columnar deforming portion 420Z is disposed along a plane including the front and rear center lines, and a change in compression amount due to relative rotation around the front and rear center lines is avoided. The sensor 430 receives a load in the shear direction, but does not affect the output of the sensor 430Z that detects the load in the front-rear direction, as described above.

Note that, for example, even when a vertical load and a vertical moment are applied in combination, the amount of compression due to relative rotation varies depending on the deflection of the columnar deforming portion 420Z and the characteristics of the load sensor 430Z. It is avoided and the load in the vertical direction can be detected.
When the longitudinal load is applied to the shaft 12 and when the longitudinal moment is applied, the direction is different depending on whether the vertical load is applied to the shaft 12 or the vertical moment is applied, respectively. Since it is the same except for the difference, the description is omitted.

  As described above, in the wheel shaft holding device 400, the amount of compression in the axial direction of the columnar deformable portion 420 is changed according to the relative displacement in the direction in which the cylindrical portion 20 and the base body 440 approach and separate from each other. The load applied to 12 is detected. On the other hand, the columnar deformable portion 420 bends in accordance with the relative displacement in the shear direction between the cylindrical portion 20 and the base 440, thereby preventing displacement at the contact surface between the support-side rod 434 and the sensor 430 and lowering the detection accuracy. Is suppressed.

  In this embodiment, the rigidity of the rods 434 and 436 is determined by the same method as in the first embodiment. The bending rigidity of the rods 434 and 436 in the right-angle direction (shear direction) perpendicular to the axial direction is the portion excluding the rod insertion portion 456 and the portion inserted into the rod insertion hole 460, that is, the right-angle direction. Assume that the part where displacement is allowed is evaluated.

Still another embodiment (relative rotation center passing / tilting type) will be described.
In the wheel shaft holding device 400, the columnar deforming portion 420 is disposed on a straight line that is orthogonal to the axis of the shaft 12 and does not include a component in the axial direction (Y). On the other hand, as shown in FIGS. 25 to 27, the columnar deformable portion 420 can be disposed on a straight line that intersects the axis of the shaft 12 and includes a component in the axial direction (Y).
In the present embodiment, the wheel shaft holding device 500 has the same configuration as that of the wheel shaft holding device 400. Therefore, the same parts are denoted by the same reference numerals, and the description thereof is omitted. explain. In addition, compared with the wheel shaft holding device 400, the cylindrical portion 20 is elongated in the axial direction.

In the wheel shaft holding device 500, as shown in FIGS. 25 to 27, the relative displacement reflecting portion 510 and the columnar deforming portion 420 are disposed at four locations, the top and bottom (Z) and the front and rear (X) of the cylindrical portion 20, respectively. ing. Since the four relative displacement reflecting portions 510 and the columnar deforming portion 420 have the same configuration, one is enlarged and shown in FIG. 28 as a representative example.
The relative displacement reflecting portion 510 includes a rod support portion 520 (a type of supported side pressing portion) that supports the end portion of the columnar deformable portion 420 from the outer peripheral side. The rod support portion 520 includes a base body 522 and a holder 450. The base 522 is located on the outer peripheral side of the flat hole 414 and is connected to the two fastened portions 418. In addition, the base 522 is provided with a flange 526 that extends toward the hub 14 in the axial direction of the shaft 12.
The flange portion 526 is provided with a through hole 528 into which the holder 450 is press-fitted. The through hole 528 is a straight line passing through the center O that is the intersection of the relative rotation axis around the vertical center line (Z) between the cylindrical portion 20 and the fastened portion 418 and the relative rotation axis around the front and rear center line (X). N is assumed to be a central axis. The center O is located on the axis of the shaft 12.
Further, the relative displacement reflecting portion 510 includes a wheel side support portion 530 (a kind of wheel side pressing portion) that supports the end portion of the columnar deformation portion 420 from the inner peripheral side. The wheel side support portion 530 is provided at the outer peripheral portion of the cylindrical portion 20 and through which the straight line N passes. The wheel side support portion 530 is provided with a rod insertion hole 532 that is tightly fitted to the end portion of the inner circumferential side rod 436 along the straight line N. The rod insertion hole 532 has a rod insertion hole 532 attached to the inner circumferential side rod 436. The end is inserted.

The operation will be described.
In the wheel shaft holding device 500, the relative displacement between the cylindrical portion 20 and the base body 522 is the same as that of the wheel shaft holding device 400. However, unlike the wheel shaft holding device 400, the columnar deformation portion 420 is disposed in a direction including the component in the axial direction (Y) in addition to the component in the vertical direction (Z) or the front-rear direction (X). For example, a load including components in the vertical direction and the axial direction is detected at the same time. Therefore, it is desirable to acquire a load for each direction.
The upper and lower relative displacement reflecting portions 510Z of the cylindrical portion 20 detect the vertical load and the axial load. Note that the load in the front-rear direction is not detected. That is, since the columnar deforming portion 420Z bends in the shearing direction, the amount of compression does not increase or decrease due to the relative displacement in the front-rear direction in the relative displacement reflecting portion 510Z, and the output of the sensor 430 is not affected. Hereinafter, a method of acquiring the load in the vertical direction and the axial direction by the vertical relative reflection reflecting portion 510Z will be described.

When a load in the vertical direction (Z), for example, a load in the direction of raising the shaft 12, is applied to the shaft 12, the amount of compression of the columnar deformed portion 420Z of the upper relative displacement reflecting portion 510Z increases, and the lower side The amount of compression of the columnar deformed portion 420Z decreases.
Here, assuming that the angle at which the straight line N intersects the axis of the shaft 12 is θ and the relative displacement amount in the vertical direction is Za, as shown in FIG. 29, the amount of increase in the compression amount of the upper columnar deformed portion 420Z is “Za · sin θ”, the amount of increase in the compression amount of the lower columnar deforming portion 420Z is “−Za · sin θ” (that is, Za · sin θ decreases). During the relative displacement, the columnar deformed portion 420Z bends in the shear direction by Za · cos θ, but does not affect the output.
On the other hand, when a load in the axial direction (Y), for example, a load in a direction to move the shaft 12 toward the hub 14 in the axial direction is applied to the shaft 12, the columnar deformation portion 420Z of the upper and lower relative displacement reflecting portions 510Z. The amount of compression increases. Then, assuming that the relative displacement amount in the axial direction is Ya, as shown in FIG. 30, the amount of increase in the compression amount of the upper and lower columnar deformed portions 420Z is “Ya · cos θ”.
When the cylindrical portion 20 and the fastened portion 418 are relatively rotated around the vertical center line, the front-rear center line, etc., the columnar deformation portion 420Z bends in the shear direction, and the amount of compression in the load detection direction is Almost no increase or decrease. Therefore, the output of the sensor 430 is not affected by the relative rotation between the cylindrical portion 20 and the fastened portion 418.

Then, the increase amounts U1 and U2 of the compression amount of the upper and lower columnar deformed portions 420Z are respectively expressed by the following equations.
U1 = Za · sin θ + Ya · cos θ (4-1)
U2 = −Za · sin θ + Ya · cos θ (4-2)
When these are solved for Za and Ya, the following equation is obtained.
Za = (U1-U2) / (2sinθ) (4-3)
Ya = (U1 + U2) / (2cosθ) (4-4)
That is, the increase amounts U1 and U2 of the compression amount are acquired based on the outputs of the upper and lower sensors 430Z, and the relative displacement amounts Za, in the vertical direction (Z) and the axial direction (Y) are obtained from the increase amounts U1 and U2 of the compression amount. Ya is determined. Based on these relative displacement amounts Za and Ya, loads in the vertical direction and the axial direction can be acquired.
The compressive load applied to the upper and lower columnar deformed portions 420Z is obtained based on the output of the upper and lower sensors 430Z, and the vertical direction of the compressive load is calculated by the same formulas as the formulas (4-3) and (4-4). By obtaining the components in (Z) and the axial direction (Y) and multiplying them by a predetermined coefficient, the load in the vertical direction and the axial direction can be acquired.

In the wheel shaft holding device 500, when the cylindrical portion 20 can be rotated relative to the flange 410 about a straight line orthogonal to the axis of the shaft 12, each columnar deformable portion 420 bends in the shearing direction, thereby Relative rotation does not affect the output of 430. In other words, in this embodiment, each columnar deforming portion 420 is disposed on a straight line passing through the center O that is the intersection of the relative rotational axes of the flange 410 and the cylindrical portion 20 (shaft 12) in the vertical direction and the front-rear direction. Therefore, the amount of compression in the load detection direction is not increased or decreased by their relative rotation.
Further, the columnar deforming portion 420 of the present embodiment is similar to the columnar deforming portion 26 of the above-described embodiment in that the rods 434 and 436 have rigidity and the like so that the rods 434 and 436 and the sensor 430 do not shift on their contact surfaces. Has been determined.

Another embodiment (multiple rod parallel type) different from the above will be described.
In all the embodiments described above, the support side rod and the like are configured by one rod member, but the support side rod and the like can also be configured by a plurality of rod members.
FIG. 31 shows a wheel shaft holding device 600. Since many portions of the wheel shaft holding device 600 are the same as those of the wheel shaft holding device 400, the same components are denoted by the same reference numerals, description thereof is omitted, and different portions are mainly described.

The wheel shaft holding device 600 is provided with a plurality of relative displacement reflecting portions 610 and columnar deforming portions 620, and in the present embodiment, provided at four locations, up and down and front and rear. Since the four relative displacement reflecting portions 610 and the columnar deforming portion 620 have the same configuration, one is enlarged in FIG. 31 and will be described representatively.
The columnar deformable portion 620 includes a parallel rod portion 624 in which a plurality of rod members 622 are arranged in parallel and a sensor 430 arranged in series. FIG. 32 shows a view of the parallel rod portion 624 as viewed from the axial direction thereof. The plurality of rod members 622 are three in this embodiment, and are arranged so as to be able to move relative to each other. Moreover, each rod member 622 is a kind of support body, has a cylindrical shape, and is formed of a steel material that is a metal material.
The parallel rod portion 624 is provided with a bowl-shaped receiving member 630 that covers end portions of the plurality of rod members 622. The receiving member 630 includes a disk portion 632 and an annular wall portion 634, and makes surface contact with the ends of the plurality of rod members 622 in the disk portion 632, and ends of the plurality of rod members 622 in the annular wall portion 634. Besiege. In this embodiment, a clearance is provided between the annular wall portion 634 and the plurality of rod members 622. However, it is also possible to adopt a mode in which no clearance is provided. The receiving member 630 is in surface contact with the sensor 430 on the surface of the disc portion 632 opposite to the annular wall portion 634. It is not essential to provide the receiving member 630, and the plurality of rod members 622 and the sensor 430 can be brought into direct surface contact. Further, the plurality of rod members 622 and the receiving member 630 can be bonded, and the receiving member 630 and the sensor 430 can be bonded.

The relative displacement reflecting part 610 includes a rod support part 636 that is a supported side pressing part and a wheel side support part 638 that is a wheel side pressing part.
The rod support portion 636 includes a base body 440 and a holder 640 that is press-fitted into the through hole 442 of the base body 440. The holder 640 has a bottomed cylindrical shape with one end closed, and includes a cylindrical portion 642 and a bottom portion 644. The cylindrical portion 642 has an inner diameter that is sufficiently separated from the plurality of rod members 622 and allows displacement of the plurality of rod members 622 in the shearing direction. The bottom portion 644 is brought into surface contact with the outer peripheral end portions of the plurality of rod members 622. A resin ring 646 is disposed between the outer peripheral end of the plurality of rod members 622 and the inner peripheral wall of the cylindrical portion 642, and the ends of the plurality of rod members 622 are the center of the cylindrical portion 642. To be located.
The wheel side support portion 638 is formed on the wall surface on the inner peripheral portion 413 side of the flat hole 414, is a contact surface orthogonal to the parallel rod portion 624, and is in surface contact with the sensor 430.

The operation and the like in this embodiment are the same as those of the wheel shaft holding device 400.
The rigidity of the plurality of rod members 622 will be described.
As described above, the rigidity of the plurality of rod members 622 when expanding and contracting in the axial direction satisfies the following relationship. That is, the ratio between “the series rigidity of the parallel rod portion 624 and the sensor 430” and “the rigidity in the vertical (front-rear) direction of the four spoke portions 416” is set to a set ratio. Further, there is a difference between a preload that is a load applied to the load sensor 74 in the standard state and a load applied to the load sensor 74 when the relative displacement amount in the load detection direction between the fastening portion 52 and the cylindrical portion 20 is maximized. The value is within the setting range. If the length of the parallel rod portion 624, the total cross-sectional area of the plurality of rod members 622, and the material are the same as those of the two rods 76 and 78, the rigidity in the axial direction makes the rods 76 and 78 in series. It becomes equal to the rigidity of those arranged in a row. The length of the parallel rod portion 624 is “2L” when the two rods 76 and 78 are arranged in series.

The bending rigidity of the plurality of rod members 622 in the perpendicular direction (shear direction) perpendicular to the axial direction will be described.
The plurality of rod members 622, like the support-side rod 232, is an expression (1-4) that is a condition for preventing displacement on the contact surface, and an expression (3-4) that is a condition for preventing peeling of the contact surface. It is assumed that The compression load P3 applied to each rod member 622 is one third of the total compression load P. Therefore, in the above formulas (1-5), (1-6), and (3-3) It is necessary to replace the compressive load P with P3 (P3 = P / 3). Also, the preload P0 and the assumed maximum compression load decrease Ps are each one third.
In the present embodiment, the support side rods and the like are made into a plurality of rod members 622, so that the total of the length, material, and cross-sectional area is easy to bend as compared to one support side rod or the like, and the shear direction deviation is reduced. It becomes easy to prevent. Moreover, it becomes easy to prevent peeling of the contact surface.
As a specific example, the rod member 622 may have an overall length 2L of 18 mm, a diameter d of 0.8 mm, and a Young's modulus E of 200 GPa. In this example, when the maximum relative displacement amount δm in the shear direction is 100 μm, the maximum resistance bending stress σp due to the force that prevents the contact surface from separating is sufficiently larger than twice the bending stress σt. Has been enlarged to. The sensor 430 has an area of 4 mm ² and a minimum compressive load of approximately 150 N (450 N for the three rod members 622).

  In the five embodiments, the parallel rod portion 624 can be employed. Moreover, you may arrange | position the parallel rod part 624 on both sides of a sensor like 1st Example.

  In the six embodiments, the support rods of the rod support portions of the first to third embodiments can be supported by the holder 450 similar to that of the fourth embodiment. Conversely, in the fourth to fifth embodiments, the base end portion of the support side rod can be press-fitted into the rod fitting portion 104 as in the first embodiment. Moreover, the rod support part of 4th-5th Example can also press-fit a support side rod to an axial direction with a volt | bolt.

It is front sectional drawing which shows the wheel-axis holding | maintenance apparatus which is an Example of claimable invention. It is a side view of the said wheel shaft holding | maintenance apparatus. It is a front view of the said wheel shaft holding | maintenance apparatus. It is a figure which expands and shows the relative displacement reflection part of the said wheel shaft holding | maintenance apparatus. It is a perspective view which shows the said wheel shaft holding | maintenance apparatus ceramic sensor. It is a figure which shows typically the hysteresis which appeared in the conventional wheel shaft holding | maintenance apparatus. It is a figure which shows typically the columnar deformation part of the said wheel shaft holding | maintenance apparatus. It is front sectional drawing which shows the wheel shaft holding | maintenance apparatus different from the above. It is a side view of the said wheel shaft holding | maintenance apparatus. It is a front view of the said wheel shaft holding | maintenance apparatus. It is a figure which expands and shows the relative displacement reflection part of the said wheel shaft holding | maintenance apparatus. It is a figure which shows typically the columnar deformation part of the said wheel shaft holding | maintenance apparatus. It is a figure which shows typically the columnar deformation part of the said wheel shaft holding | maintenance apparatus. It is front sectional drawing which shows another wheel shaft holding | maintenance apparatus different from the above. It is a front view of the said wheel shaft holding | maintenance apparatus. It is a front view which expands and shows the relative displacement reflection part of the said wheel shaft holding | maintenance apparatus. It is a side view which expands and shows the relative displacement reflection part of the said wheel shaft holding | maintenance apparatus. It is a figure which shows typically the change of the compression amount of the columnar deformation part by the relative displacement of the up-down direction of the said wheel shaft holding | maintenance apparatus. It is a figure which shows typically the change of the compression amount of the columnar deformation part by the relative displacement of the axial direction of the said wheel shaft holding | maintenance apparatus. It is a figure which shows typically the change of the compression amount of the columnar deformation part by the relative rotation of the said wheel shaft holding | maintenance apparatus. It is a schematic diagram which shows arrangement | positioning of the columnar deformation part of the said wheel shaft holding | maintenance apparatus. It is front sectional drawing which shows another wheel shaft holding | maintenance apparatus different from the above. It is a side view of the said wheel shaft holding | maintenance apparatus. It is a side view which expands and shows the relative displacement reflection part of the said wheel shaft holding | maintenance apparatus. It is front sectional drawing which shows another wheel shaft holding | maintenance apparatus different from the above. It is a front view of the said wheel shaft holding | maintenance apparatus. It is a side view of the said wheel shaft holding | maintenance apparatus. It is front sectional drawing which expands and shows the relative displacement reflection part of the said wheel shaft holding | maintenance apparatus. It is a figure which shows typically the change of the compression amount of the columnar deformation part by the relative displacement of the up-down direction of the said wheel shaft holding | maintenance apparatus. It is a figure which shows typically the change of the compression amount of the columnar deformation part by the relative displacement of the axial direction of the said wheel shaft holding | maintenance apparatus. It is front sectional drawing which shows the relative displacement reflection part of another wheel shaft holding | maintenance apparatus different from the above. It is the figure which looked at the parallel rod part of the said wheel shaft holding | maintenance apparatus from the axial direction.

Explanation of symbols

  <First embodiment> 10: Wheel shaft holding device 12: Shaft (wheel shaft) 20: Cylindrical portion (main body of holding body) 22: Support body 24: Relative displacement reflecting portion 26: Columnar deformation portion (load detecting device) 30: Ball bearing (bearing) 52: Fastened part (attached part) 54: Spoke part (bridge part) 60: Arm part (wheel side pressing part) 72: Rod support part (supported side pressing part) 74: Ceramic sensor ( (Load sensor) 76: Support side rod 78: Arm side rod <Second embodiment> 200: Wheel shaft holding device 210: Relative displacement reflecting portion 220: Columnar deformation portion (load detection device) 222: Arm portion (wheel side pressing portion) 230: Ceramic sensor (load sensor) 232: Support side rod <Third embodiment> 300: Wheel shaft holding device 310: Relative displacement reflecting unit 320: Columnar deformation part (load detection device) 322: Rod support part (supported side pressing part) 324: Arm part (wheel side pressing part) 330: Ceramic sensor (load sensor) 334: Support side rod 336: Arm side rod 340: Rod receiving portion <Fourth embodiment> 400: Wheel shaft holding device 410: Flange portion 412: Outer peripheral portion 413: Inner peripheral portion 414: Flat hole 416: Spoke portion (bridge portion) 418: Fastened portion (attached) 419: Relative displacement reflecting part 420: Columnar deformed part (load detecting device) 422: Rod support part (supported side pressing part) 424: Wheel side supporting part (wheel side pressing part) 430: Ceramic sensor (load sensor) 434: Support side rod 436: Inner circumference side rod <Fifth embodiment> 500: Wheel shaft holding device 5 0: Relative displacement reflecting portion 530: Wheel side supporting portion (wheel side pressing portion) <Sixth embodiment> 600: Wheel shaft holding device 610: Relative displacement reflecting portion 620: Columnar deforming portion (load detecting device) 622: Rod member (Post body) 624: Parallel rod part (columnar transmission body) 636: Rod support part (supported side pressing part) 638: Wheel side support part (wheel side pressing part)

Claims (13)

A supported body supported by the suspension device;
A wheel shaft holder for holding the wheel shaft;
A connecting body for connecting the supported body and the wheel shaft holding body;
(a) a load sensor for detecting a load in a specific direction; (b) a columnar shape extending in the specific direction; and in series with the load sensor between the supported body and the wheel shaft holder in the specific direction. And a columnar transmission body that transmits at least part of the relative displacement between the supported body and the wheel shaft holder in the specific direction to the load sensor, and the columnar transmission body is made of the same material as the columnar transmission body. A wheel shaft holding device including one or more load detection devices that are more easily elastically deformed than a cylinder whose length is twice the diameter.   In the range where the columnar transmission body is at least a load applied to the wheel shaft does not exceed the maximum load, according to the relative displacement between the supported body and the wheel shaft holder in a right angle direction perpendicular to the specific direction, 2. The wheel shaft holding device according to claim 1, wherein the wheel shaft holding device is elastically bent in the right-angle direction without shifting from the load sensor on a contact surface with the load sensor. 3.   In the columnar transmission body, the maximum relative displacement between the supported body and the wheel shaft holder in the perpendicular direction is the maximum relative displacement between the supported body and the wheel shaft holder in the specific direction. Even when the load sensor is larger than the load sensor, the contact surface with the load sensor does not deviate from the load sensor according to the relative displacement between the supported body and the wheel shaft holder in the perpendicular direction. The wheel shaft holding device according to claim 1 or 2, wherein the wheel shaft holding device is elastically bent.   The pressure applied to the load sensor in the standard state by the columnar transmission body, and the pressure applied to the load sensor in a state where the relative displacement between the supported body and the wheel shaft holder in the specific direction is maximized. The wheel shaft holding device according to any one of claims 1 to 3, wherein the difference is 5 MPa or more. At least one of the one or more load detection devices is provided with a separation preventing force that prevents the load sensor and the columnar transmission body from separating in the specific direction on their contact surfaces. Yes,
In the range where the columnar transmission body does not exceed the maximum load at least, the maximum value of the bending stress acting on the end of the columnar transmission body when the columnar transmission body is bent in the perpendicular direction is the separation distance. The wheel shaft holding device according to any one of claims 1 to 4, wherein the wheel shaft holding device is smaller than a maximum value of the resistance bending stress that can be generated by the prevention force.   At least one of the one or more load detection devices includes a relative rotation center line when the supported body and the wheel shaft holder are relatively rotated by a moment in a direction orthogonal to the wheel shaft. The wheel shaft holding device according to any one of claims 1 to 5, wherein the wheel shaft holding device is disposed along a plane.   At least one of the one or more load detection devices rotates the supported body and the wheel shaft holder relative to each other by moments in two directions orthogonal to the wheel shaft and different from each other. The wheel shaft holding device according to any one of claims 1 to 6, wherein the wheel shaft holding device is disposed along a straight line passing through an intersection of two relative rotation center lines.   The wheel shaft holding device according to any one of claims 1 to 7, wherein at least one of the one or more load detection devices is disposed along a plane orthogonal to the wheel shaft.   An inclination in which at least one of the one or more load detection devices includes a direction including a component in a direction parallel to the wheel axis and a direction including at least one of a vertical direction and a front-rear direction in the vehicle. The wheel shaft holding device according to any one of claims 1 to 7, wherein a direction is set as the specific direction. The supported body includes a plurality of attached portions that are disposed apart from each other and attached to a member provided in the suspension device;
The connecting body includes a plurality of bridge portions that connect each of the plurality of attached portions and the wheel shaft holding body,
The each of the one or more load detection devices is disposed between each of the one or more of the plurality of attached portions and the wheel shaft holder. Wheel shaft holding device. Each of the plurality of attached portions is disposed radially away from the wheel shaft holder,
The plurality of bridge portions connect each of the plurality of attached portions and the wheel shaft holder along a radial direction,
The wheel axle holder is connected to the plurality of attached portions by the plurality of bridge portions, and between the two adjacent ones of the plurality of attached portions to the holder body. A wheel-side pressing part that is provided and presses one of the one or more load detection devices between one of the two attached parts adjacent to each other in the specific direction. The wheel shaft holding device according to claim 10. Each of the plurality of attached portions is disposed on one circumference having a diameter larger than that of the holding body,
The wheel shaft holding device according to claim 11, wherein the wheel side pressing portion is formed to protrude radially outward from the holding body main body. The wheel side pressing portion is provided radially outward on the outer peripheral portion of the holding body main body,
The supported body is connected to two adjacent ones of the plurality of attached portions at both ends, and faces the wheel-side pressing portion at an intermediate portion, and the one or more load detecting devices The wheel shaft holding device according to claim 11, comprising a supported-side pressing portion that presses one of them to the wheel-side pressing portion side.

Images