JP2019105469A - Load sensor and electric brake - Google Patents

Abstract

To acquire a load sensor which is not affected by load history, and an electric brake using the same.SOLUTION: A load sensor 9 includes a first strain sensor 93, a first distorted body 91 on which the first strain sensor is mounted; and a second distorted body 92 arrange in series in the load direction with respect to the first distorted body. The first distorted body includes: a pressure receiving part 91b where a load is inputted toward the second distorted body along the load direction; and a pair of bank parts 91a arranged in positions separated from each other in the direction crossing the input direction of the load from the pressure receiving part 91b, and facing the second distorted body 92. The second distorted body 92 includes: a support surface 92b where a load is inputted toward the first distorted body 91 along the load direction; and a pair of contact surfaces 92c arranged in positions separated from each other in the direction crossing the input direction of the load from the support surface 92b, facing the first distorted body 91 and coming into contact with one of the bank parts 91a respectively.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a load sensor that detects a load by strain, and an electric brake equipped with the same.

  Patent Document 1 describes a configuration of a load sensor that detects a thrust load. In this patent document 1, "an annular washer-type load cell is inserted into the penetration rod, and between the washer-type load cell and the bearing, the thrust load of the penetration rod acting on the bearing is a washer-type load cell The load member of the penetrating rod is transmitted through the bearing and the transmitting member, and the thrust load of the penetrating rod is transmitted to the washer type load cell, and the strain amount of the washer type load cell is distorted according to the thrust load of the penetrating rod. It is described that "this thrust load is detected."

Patent No. 5513164 gazette

  Patent Document 1 describes a configuration in which a thrust load is applied to a washer-type load cell via a bearing and a transmission member. However, in the washer-type load cell described in Patent Document 1, when a thrust load is applied, a slight slip occurs on the contact surface of the washer-type load cell and the transmission member, and the load increases due to the frictional force generated by the slip. The deformation of the washer-type load cell and the deformation of the washer-type load cell at the time of load reduction may be irreversible, which may cause hysteresis in the load-strain characteristics of the washer-type load cell. Therefore, when the configuration of Patent Document 1 is applied to an electric brake in which the thrust load frequently changes, there is a problem that it becomes difficult to measure an accurate thrust load.

  An object of the present invention is to provide a load sensor with reduced load-strain hysteresis and an electric brake using the same.

  In order to solve the above problems, a load sensor according to the present invention includes a first strain sensor, a first straining body on which the first strain sensor is mounted, and a first straining body. And a second strain generating body disposed in series in a load direction, wherein the first strain generating body is configured to load toward the second strain generating body along the load direction. And a pair of first support portions arranged at positions separated from each other in a direction intersecting the load input direction from the first input portion and facing the second strain generating body A second input unit to which a load is input toward the first elastic body along the load direction, and an input direction of the load from the second input unit. A pair disposed at mutually separated positions in a crossing direction crossing the first pair of the first support portions to face the first strain generating body. And having a second support portion.

  ADVANTAGE OF THE INVENTION According to this invention, the load sensor which reduced the hysteresis of a load-distortion characteristic, and an electric brake using the same can be provided.

  Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. Further, problems, configurations and effects other than those described above will be clarified by the description of the following embodiments.

Sectional drawing which shows the structure of the electrically-driven brake by which this invention was mounted. BRIEF DESCRIPTION OF THE DRAWINGS The perspective sectional view which shows the structure of the load sensor of this invention. The load sensor of this invention WHEREIN: Explanatory drawing of the balance of the force concerning a strain body in the process which increases load. The load sensor of this invention WHEREIN: Explanatory drawing of balance of the force concerning a strain body in the process which reduces load. The figure which shows the load-distortion characteristic of the load sensor of this invention. Explanatory drawing explaining a deformation | transformation of the strain body of the load sensor of this invention. BRIEF DESCRIPTION OF THE DRAWINGS The perspective sectional view which shows an example of a structure of the load sensor of this invention. The load sensor of this invention WHEREIN: Explanatory drawing of the balance of the force concerning a strain body in the process which increases load. The load sensor of this invention WHEREIN: Explanatory drawing of balance of the force concerning a strain body in the process which reduces load. BRIEF DESCRIPTION OF THE DRAWINGS The perspective sectional view which shows an example of a structure of the load sensor of this invention. The perspective view sectional drawing which shows an example of a structure of a load sensor without a support surface. Explanatory drawing of the balance of the force concerning a strain body in the process which increases load in a load sensor without a support surface. Explanatory drawing of the balance of the force concerning a strain body in the process which reduces load in a load sensor without a support surface. The figure which shows the load-distortion characteristic of the load sensor without a support surface.

  Hereinafter, an embodiment of a load sensor according to the present invention will be described with reference to the drawings.

Example 1
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5.
FIG. 1 is a cross-sectional view showing the configuration of an electric brake 1 equipped with the present invention. 1 is an electric brake, 2 is a caliper housing, 3 is an electric motor, 4 is a reduction gear, 5 is a lead screw, 6 is a nut, 7 is a piston, 8 is a brake pad, and 9 is a load sensor.

  The electric brake 1 of FIG. 1 is a device that applies a braking force to the disk 10 by pressing the brake pad 8 against the disk 10 using the electric motor 3 as a drive source. The electric motor 3 is driven by a current signal or a voltage signal from an external controller to rotate the motor shaft. The rotation of the motor shaft is decelerated by the reduction gear 4 to become a large rotational force and transmitted to the lead screw 5. The lead screw 5 constitutes a linear movement mechanism together with the nut 6, and the rotation of the lead screw 5 is converted into an axial translational force. Since the nut 6 is restricted in rotation by the key groove (not shown) in the caliper housing 2 and the movement in the axial direction is also restricted, the translational force acts on the lead screw 5 and the lead screw 5 itself is rotated while rotating. Translate to The piston 7 receives the translational force of the lead screw 5 and moves toward the disk 10. The piston 7 pushes the brake pad 8 on the right side of the figure in the direction of the disc 10. When the brake pad 8 is pushed into contact with the disk 10, the caliper housing 2 is moved to the right in the figure by the reaction force. The movement of the caliper housing 2 presses the brake pad 8 on the left side of the figure against the disc 10. The disc 10 receives a braking force by being pinched by the left and right brake pads 8. The load sensor 9 contacts the nut 6, receives the reaction force applied to the nut 6 on one side, and contacts the inner wall of the caliper casing 2 on the other side. The load sensor 9 receives a load from the nut 6 and is deformed to output a voltage signal corresponding to the load to the outside.

Next, the configuration of the load sensor 9 will be described.
FIG. 2 is a perspective sectional view showing the structure of the load sensor 9 of the present invention. 9 is a load sensor, 91 is a first strain generating body, 92 is a second strain generating body, 93 is a strain sensor, 94 is a relay substrate, and 95 is a wiring. The first strain generating body 91 is provided with a bank portion 91 a and a pressure receiving portion 91 b. The second strain generating body 92 is provided with a support surface 92 b.

  The load sensor 9 includes a strain sensor (first strain sensor) 93, a first strain body 91 on which the strain sensor 93 is mounted, and a load direction indicated by an arrow N with respect to the first strain body 91. And a second strain generating body 92 disposed in series. The first strain generating body 91 includes a pressure receiving portion (first input portion) 91b to which a load is input toward the second strain generating body 92 along the load direction, and a pressure receiving portion (first input portion) 91b. A pair of bank portions (first support portions) 91 a are disposed at positions separated from each other in the direction intersecting the load input direction and are opposed to the second strain body 92. The second strain body 92 includes a support surface (second input portion) 92 b to which a load is input toward the first strain body 91 along the load direction, and a support surface (second input portion). A pair of contact surfaces disposed at mutually separated positions in a cross direction crossing the load input direction from 92b and facing the first strain generating body 91 and contacting the pair of bank portions (first support portions) 91a respectively And (second support portion) 92c.

Details of components of the load sensor 9 of the present invention will be described.
The first strain generating body 91 has a ring shape in the center of which a hole through which the lead screw 5 passes is provided. The outer shape is a circular shape that fits inside the piston 7. These external shapes do not necessarily have to be circular depending on the design of the electric brake 1 and may be, for example, rectangular or elliptical. Further, for example, when the load sensor 9 is attached to the outside of the caliper housing 2 and the load sensor 9 receives a load by the end face of the lead screw 5, the hole through which the lead screw 5 passes is not necessarily provided. .

  The first strain generating body 91 is provided with two pressure receiving portions 91 b on the bottom surface. The pressure receiving portion 91 b has a shape that protrudes one step beyond the bottom surface, and is a contact point with the nut 6. Since the load is concentrated on the pressure receiving portion 91b, the pressure receiving portion 91b is designed to have an area not exceeding the yield limit of the material at the maximum load. In this embodiment, the pressure receiving portion 91b is provided on the first strain generating body 91, but may be provided on the nut 6 side. In that case, the rotation stopper of the nut 6 provided in the caliper casing 2 is configured to reduce the backlash so as not to cause the positional displacement of the load point with respect to the first strain generating body 91.

  On the upper surface of the first strain generating body 91, two bank portions 91a are provided. In addition, a strain sensor 93, a relay substrate 94, and a wire 95 are mounted in a recess between the two bank portions 91a. A space is formed between the first strain generating body 91 and the second strain generating body 92 by the bank portion 91a, and the strain sensor 93, the relay substrate 94, and the wiring 95 can be mounted in the space. The first strain generating body 91 is made of a high strength steel because it is used under a high load. In addition, surface treatment or the like may be performed to improve resistance.

  The second strain generating body 92 is provided on the lower surface with a contact surface 92 c in contact with the bank portion 91 a of the first strain generating body 91. Further, a support surface 92 b in contact with the inner wall of the caliper casing 2 is provided on the upper surface. The support surface 92 b is shaped to project one step higher than the upper surface, and is a contact point with the caliper housing 2. The second strain body 92 is disposed in series with the first strain body 91 in the load direction, and is a first strain body as a protective cap of the strain sensor 93 or the like mounted on the first strain body 91. It is put on 91. Since a high load is also applied to the second strain generating body 92, the second strain generating body 92 is made of a high strength steel material.

  The strain sensor 93 is, for example, a strain IC. Piezoresistors for detecting strain are formed in the center of the upper surface of a silicon chip, and a Wheatstone bridge, an amplification circuit, a temperature assurance circuit, etc. are formed around the periphery by semiconductor processing. The strain sensor 93 captures the strain applied to the strain sensor 93 as a resistance change by using the piezoresistance effect. The strain sensor 93 is mounted at an intermediate position between the two bank portions 91a of the first strain generating body 91, and a strain component in a linear direction connecting the bank portions 91a and a strain component in a radial direction orthogonal thereto are detected. Furthermore, the strain sensor 93 produces and outputs a voltage signal corresponding to the magnitude of the difference between the two strain components. The strain sensor 93 may be configured by a strain gauge or the like.

  The relay substrate 94 is, for example, a glass epoxy substrate. An electrode pad is formed on the relay substrate 94, and wiring is performed by wire bonding with the strain sensor 93 using this pad, and a signal is extracted from the strain sensor 93. Further, the relay substrate 94 is provided with an electrode for extracting a signal to the outside. A wire 95 made of a coated cable is directly soldered to this electrode, or a connector is provided to draw a signal to the outside.

The load detection principle of the load sensor 9 of the present invention will be described.
The first strain generating body 91 has a three-point bending structure in which the pressure receiving portion 91b is a load point and the bank portion 91a is a support point. When a load from the nut 6 is applied to the pressure receiving portion 91b, the first strain generating body 91 causes bending deformation, and the depression between the two bank portions 91a is raised in a convex shape. The strain sensor 93 joined to the surface of the first strain body 91 deforms in accordance with the first strain body 91, and outputs a voltage signal corresponding to the magnitude of strain. The signal output from the strain sensor 93 is output to the outside through the wiring 95 via the relay substrate 94.

  In the load sensor 9 of this embodiment, the support surface 92b is provided on the second strain body 92, and the second strain body 92 is deformed to improve the sensor output characteristic (load-strain characteristic). ing. In order to explain the effect of the support surface 92b provided on the second strain generating body 92, first, the problem of the structure without the support surface 92b will be described with reference to FIG. 11 to FIG.

  FIG. 11 is a perspective sectional view showing the configuration of the load sensor 9 without the support surface 92b. The configuration is the same as that of the load sensor shown in FIG. 2 except that the second strain generating body 92 does not have the support surface 92b, and therefore, the overlapping description will be omitted. The second strain generating body 92 is not provided with the support surface 92 b. Therefore, the entire upper surface is in contact with and fixed to the inner wall of the caliper casing 2.

  FIG. 12 is a diagram for explaining the balance of forces applied to the first strain generating body 91 in the process of increasing the load N in the load sensor 9 without the support surface 92b. In FIG. 12, N is a load, μ is a friction coefficient, and F is a friction force. Thin arrows in the figure indicate the position and direction of application of force. The thick arrows indicate the displacement direction of the bank portion 91 a of the first strain generating body 91.

  A load N indicated by an upward arrow is applied to the center of the lower surface of the first strain generating body 91. This shows the load N received from the nut 6 to the pressure receiving portion 91 b of the first strain generating body 91. A drag N / 2 against a load N is applied to the bank portion 91a of the first strain generating body 91. The first strain generating body 91 is subjected to three-point bending with a load N and a resistance N / 2. By the three-point bending, the first strain generating body 91 causes a bending deformation in which the central portion is bent in a convex shape.

  When the load N is further increased from this state, the deformation of the first strain generating body 91 becomes large, and the bank portion 91a is displaced so as to open in the direction of the thick arrow. At this time, since the second strain generating body 92 is fixed and supported by the inner wall of the caliper casing 2 at the upper surface, no deformation occurs at the contact surface of the first strain generating body 91 with the bank portion 91a. . Therefore, relative displacement occurs between the bank portion 91a of the first strain generating body 91 and the contact surface of the second strain generating body 92, and slippage occurs on the contact surface. When slippage occurs, a frictional force F is generated in the direction to prevent displacement. The frictional force F is expressed by the product of the coefficient of friction μ and the drag N / 2, and if the coefficient of friction μ is zero, no frictional force F is generated, but if the coefficient of friction μ is not zero, the frictional force F acts and It prevents the deformation of the first strain generating body 91.

  FIG. 13 is a view for explaining the balance of forces applied to the first strain generating body 91 in the process of decreasing the load N in the load sensor 9 without the support surface 92b. With respect to FIG. 12, the direction of the thick arrow and the direction of the frictional force F are different.

  When the load N is reduced from the state of three-point bending, the deformation of the first strain generating body 91 becomes smaller, and the bank portion 91a is displaced so as to close in the direction of the thick arrow in the figure. Due to this displacement, relative displacement occurs between the bank portion 91a of the first strain generating body 91 and the contact surface of the second strain generating body 92, and slippage occurs on the contact surface. At this time, since the frictional force F accompanying the slip is generated in the direction to prevent the displacement of the bank portion 91a, the deformation of the first strain generating body 91 becomes difficult to return.

  FIG. 14 is a view showing load-strain characteristics of the load sensor 9 without the support surface 92b. In the figure, the solid line shows the load-strain characteristic when the coefficient of friction μ is not zero. Arrows in the figure indicate a process of increasing the load N (A characteristic) and a process of decreasing the load N (B characteristic). The dotted line shows the load-strain characteristic when the friction coefficient μ is zero.

  In the process of increasing the load N, the first strain generating body 91 is less likely to be deformed by the frictional force F, and therefore, the A characteristic in which the slope is smaller than the load-strain characteristic when the friction coefficient μ shown by the dotted line is zero. Change. In the process of decreasing the load N, the deformation of the strain generating body 91 is difficult to return due to the frictional force F, and therefore, the transition is made along the B characteristic having a larger inclination than the load-strain characteristic when the friction coefficient μ is zero. At the switching of the increase and decrease of the load, the transition from the line of the A characteristic to the line of the B characteristic, and from the line of the B characteristic to the line of the A characteristic is made. In the switching between the A characteristic and the B characteristic, the load-strain characteristic exhibits the influence of hysteresis of load increase / decrease (hysteresis).

  The load sensor 9 without the support surface 92b is difficult to obtain an accurate value because the load value is affected by the hysteresis when the load increases or decreases. In addition, when the load sensor 9 is applied to the electric brake 1, the measured value of the load changes depending on the history of braking, so that the braking force can not be finely controlled, and the advantage of using the load sensor may not be obtained. .

  Next, the load sensor 9 according to the present invention provided with the support surface 92b will be described with reference to FIGS.

  FIG. 3 is a view for explaining the balance of forces applied to the first strain generating body 91 and the second strain generating body 92 in the process of increasing the load N in the load sensor 9 of the present invention.

  In FIG. 3, N is a load, μ is a coefficient of friction, and F is a frictional force. Arrows in the figure indicate the position and direction of the force applied to the strain generating bodies 91 and 92. In addition, thick arrows indicate the displacement directions of the contact surfaces of the strain generating bodies 91 and 92. The solid line indicates the force and displacement applied to the first strain generating body 91, and the dotted line indicates the force applied to the second strain generating body 92.

  A load N indicated by an upward arrow is applied to the center of the lower surface of the first strain generating body 91. This shows the load N received from the nut 6 to the pressure receiving portion 91 b of the first strain generating body 91. A drag N / 2 against a load N is applied to the bank portion 91a of the first strain generating body 91. The first strain generating body 91 is subjected to three-point bending with a load N and a resistance N / 2. By the three-point bending, the first strain generating body 91 causes a bending deformation in which the central portion is bent in a convex shape. When the load N is further increased from this state, the deformation of the first strain generating body 91 becomes large, and the bank portion 91a is displaced so as to open in the direction of the thick arrow.

  The second strain body 92 receives a load N / 2 at the contact surface of the first strain body 91 with the bank portion 91a, and receives a reaction force N against the load N from the caliper housing 2 at the support surface 92b. Three-point bending is performed. By the three-point bending, the second strain generating body 92 causes a bending deformation in which the central portion is depressed downward. When the load N is further increased from this state, the deformation of the second strain body 92 becomes large, and the contact surface of the first strain body 91 with the bank portion 91 a opens in the direction of the thick dotted arrow. Displace.

  At this time, the displacement of the bank portion 91a of the first strain generating body 91 and the displacement of the contact surface of the second strain generating body 92 have the same displacement direction, so that the relative displacement is reduced. As the relative displacement decreases, the slip occurring on the contact surface decreases, and the friction force F decreases, so that the deformation of the first strain generating body 91 is not impeded. Therefore, the load-strain characteristic (A characteristic) can maintain the inclination when the friction coefficient μ is zero.

  FIG. 4 illustrates the balance of forces applied to the first strain generating body 91 and the second strain generating body 92 in the process of decreasing the load N in the load sensor 9 of the present invention provided with the support surface 92 b. It is.

  When the load N is reduced from the state of three-point bending, the deformation of the first strain generating body 91 becomes smaller, and the bank portion 91a is displaced so as to close in the direction of the thick arrow in the figure. Further, the deformation of the second strain generating body 92 is also reduced, and the contact surface of the first strain generating body 91 with the bank portion 91a is displaced so as to close in the direction of the thick dotted arrow. At this time, the displacement of the bank portion 91a of the first strain generating body 91 and the displacement of the contact surface of the second strain generating body 92 can be reduced in relative displacement because the displacement directions become the same. As the relative displacement decreases, the amount of sliding also decreases, so the frictional force F decreases, and the deformation of the first strain generating body 91 is not impeded. Therefore, the load-strain characteristic (B characteristic) can maintain the inclination when the friction coefficient μ is zero.

FIG. 5 is a view showing the load-strain characteristic of the load sensor 9 of the present invention provided with the support surface 92b.
If the displacement of the bank portion 91 a of the first strain generating body 9 and the displacement of the contact portion of the second strain generating body 92 can be made to completely coincide with each other, the relative displacement becomes zero and the first strain generating body 91 Frictional force F due to slippage that prevents deformation does not occur. Therefore, both the A characteristics at the time of load increase and the B characteristics at the time of load decrease become identical to the load-strain characteristics at the time when the friction coefficient μ is zero, and become reversible so that no hysteresis occurs.

  Here, even if the displacement of the bank portion 91a of the first strain generating body 9 and the displacement of the contact portion of the second strain generating body 92 can not be perfectly matched, it leads to the reduction of the relative displacement. The frictional force F due to the slip can be reduced.

  As described above, by providing the support surface 92b on the second strain generating body 92, it is possible to reduce the hysteresis of the load-strain characteristic.

  A method of matching the displacement of the bank portion 91a of the first strain generating body 91 and the displacement of the contact surface of the second strain generating body 92 will be described with reference to FIG.

  FIG. 6 is an explanatory view for explaining the deformation of the second strain generating body 92 of the load sensor 9 of the present invention. The two loads N / 2 represent the loads received from the bank portion 91 a of the first strain generating body 91. Further, the support point represents a support surface 92 b provided on the second strain generating body 92. L is the distance between the load point and the support point, Δx is the displacement of the contact surface of the second strain body 92, t1 is the distance in the thickness direction from the neutral plane NS of the second strain member 92 to the contact surface, EI shows bending rigidity.

  The second strain generating body 92 has a three-point bending structure due to the load and the support point. When a load is applied, as shown in the figure, the second strain generating body 92 undergoes a bending deformation in which the central portion is depressed downward. When deflection deformation occurs, the neutral plane NS of the second strain generating body 92 does not cause displacement in the lateral direction of the figure, but since the upper surface and the lower surface away from the neutral plane NS are inclined by the deflection angle, Displacement occurs. On the upper surface, displacement occurs in the direction of closing in the center, and on the lower surface (contact surface), displacement occurs in the direction of opening outward from the center. The displacement Δx of the contact surface of the second strain generating body 92 is influenced by the distance t1 from the neutral surface NS to the lower surface. When the distance t1 from the neutral plane NS to the lower surface is changed, the thickness is also changed in conjunction. Since the bending rigidity EI is proportional to the cube of the thickness, for example, if the thickness of the second strain generating body 92 is reduced, the deflection deformation becomes dramatically large and the displacement Δx of the contact surface becomes large.

  The displacement Δx of the contact surface of the second strain generating body 92 is also influenced by the support conditions. When the distance L between the load point of the second strain generating body 92 and the support point is increased, the deflection angle of the contact point is increased, so the displacement Δx due to the distance t1 from the neutral plane NS to the lower surface is increased.

  In the load sensor 9 of the present embodiment, an example in which the thickness of the second strain generating body 92 is made thinner than the thickness of the first strain generating body 91 is shown. When the thickness of the second strain body 92 becomes thinner than the thickness of the first strain body 91, the bending rigidity EI of the second strain body 92 becomes low and it becomes easy to be deformed. The displacement Δx 92 is larger than the displacement of the bank portion 91 a of the first strain generating body 91, which causes hysteresis. Therefore, the deflection angle is reduced by shortening the distance L between the load point and the support point by widening the width of the support surface 92b provided on the second strain generating body 92, and the displacement Δx is suppressed small. . Regarding the length L of the distance between the load point and the support point, the displacement Δx of the contact surface of the second strain generating body 92 is estimated by structural analysis using the finite element method, and the bank portion 91 a of the first strain generating body 91 It should be designed with the value when it agrees with the displacement of.

  As described above, the load sensor 9 and the electric brake 1 according to the present embodiment include the strain sensor 93, the first straining body 91 having the strain sensor 93 mounted thereon, and the first straining body 91 in series in the load direction. In the load sensor 9 having the second strain generating body 92 disposed, when the load N acts, the first strain generating body so that the displacement direction on the contact surface of the first strain forming body 91 is on the outer side While setting the deformation shape of 91, the deformation shape of the second strain generating body 92 was set so that the displacement direction on the contact surface of the second strain generating body 92 was on the outside.

  According to this, the displacement direction of the bank portion 91a of the first strain generating body 91 and the displacement direction of the contact portion of the second strain generating body 92 are made to coincide with each other to reduce the relative displacement. Since the hysteresis generated in the load-strain characteristic can be reduced, the load N can be measured with high accuracy. Further, since the load N can be accurately measured, the braking force control of the electric brake 1 can be set finely, which can contribute to the improvement of the ride quality of the vehicle.

  In this embodiment, the first strain body 91 and the second strain body 92 are arranged in series in the thrust load direction, and the displacement of the first strain body 91 when the thrust load is received on the contact surface thereof. Since the deformation shapes of the strain generating bodies 91 and 92 are set so that the displacement of the second strain generating body 92 is in the same direction, the relative displacement on the contact surface can be reduced. Therefore, the hysteresis can be reduced, and the load N can be measured with high accuracy.

(Example 2)
Next, a second embodiment of the load sensor 9 according to the present invention will be described with reference to FIGS. 7 to 9.
FIG. 7 is a perspective sectional view showing the configuration of the load sensor 9 of the present invention. The present embodiment shown in FIG. 7 differs from the configuration of FIG. 2 in the shape of the second strain generating body 92. The configuration other than the second strain generating body 92 will be omitted because it will be described again.

  The second strain body 92 has the same shape as the first strain body 91, and is arranged to be plane-symmetrical. By forming the first strain generating body 91 and the second strain generating body 92 with the same parts, the same deformation can be obtained when the load N is applied, and mass production can be performed rather than providing parts of different shapes. An effect is obtained. The second strain body 92 has the bank portion (second support portion) 92a facing the bank portion (first support portion) 91a of the first strain body 91, and has a mirror image relative to the contact surface. Arrange as follows.

  The strain sensor 93, the relay substrate 94, and the wiring 95 are provided on at least one of the strain generating members. When the strain sensor 93 is provided on each straining body, even if one of the strain sensors 93 breaks down and no output can be obtained, the other output which is not broken can be obtained, so fail safe is realized. Can contribute to the improvement of reliability. Also, rather than providing two strain sensors 93 on one straining body 91, the strain sensor 93 is provided on each of the two straining bodies, thereby achieving one more yield than mounting two strain sensors 93. Since the yield to be mounted is higher, it can lead to improvement in productivity.

  FIGS. 8 and 9 are diagrams for explaining the balance of forces applied to the first strain generating body 91 and the second strain generating body 92 according to the present invention.

  FIG. 8 shows the force balance in the process of increasing the load N. The load N from the nut 6 is applied to a pressure receiving portion 91 b provided to the first strain generating body 91. The first strain generating body 91 receives a resistance N / 2 at the bank portion 91a and has a three-point bending structure. The first strain generating body 91 causes bending deformation in a direction in which the bank portion 91a opens outward as shown by a thick arrow when a load N is applied. On the other hand, the second strain body 92 receives a load N / 2 from the first strain body 91 to the two bank portions 92a. The second strain body 92 is supported by the support surface 92 b on the inner wall of the caliper casing 2 and has a three-point bending structure. The second strain generating body 92 causes bending deformation in a direction in which the bank portion 92a opens outward as shown by a thick dotted arrow by applying a load N. At this time, since the displacement of the contact surface of the bank portion 91a of the first strain generating body 91 and the displacement of the contact surface of the bank portion 92a of the second strain generating body 92 are the same displacement and direction, they are relative displacements. There is no slippage. Since the friction force F generated by the slip does not occur, the force for preventing the deformation of the first strain generating body 91 does not work, and the load-strain characteristic has the same inclination as when the friction coefficient μ is zero.

  FIG. 9 shows the force balance in the process of reducing the load N. When the load N is reduced, the first strain generating body 91 and the second strain generating body 92 both displace in a direction in which the bank portions 91a and 92a close toward the center as indicated by thick arrows. The displacement that occurs here is also the same displacement and direction, so there is no relative displacement and no slippage occurs. For this reason, since the frictional force F generated by the slip is not generated, the force for preventing the deformation of the first strain generating body 91 does not work, and the load-strain characteristic has the same inclination as the friction coefficient μ is zero.

  In both the process of increasing the load N and the process of reducing the load N, the load-distortion characteristics have the same slope, so that the occurrence of hysteresis can be suppressed.

  As described above, the load sensor 9 and the electric brake 1 according to the present embodiment include the strain sensor 93, the first straining body 91 having the strain sensor 93 mounted thereon, and the first straining body 91 in series in the load direction. In the load sensor 9 having the second strain generating body 92 disposed, when the load N acts, the first strain generating body so that the displacement direction on the contact surface of the first strain forming body 91 is on the outer side The deformation shape of 91 is set, and the second strain body 92 has the same shape as the first strain body 91 so that the displacement direction on the contact surface of the second strain body 92 is the outer side.

  According to this, by making the displacement direction of the bank portion 91a of the first strain generating body 91 coincide with the displacement direction of the bank portion 92a of the second strain generating body 92, the load sensor 9 is reduced by reducing the relative displacement. Since it is possible to reduce the hysteresis generated in the load-distortion characteristics of (1), it is possible to measure the load N with high accuracy. Further, since the load N can be accurately measured, the braking force control of the electric brake 1 can be set finely, which can contribute to the improvement of the ride quality of the vehicle.

(Example 3)
Hereinafter, an embodiment of the present invention will be described with reference to FIG.
FIG. 10 is a perspective sectional view showing the configuration of the load sensor 9 of the present invention.
In the structure of the load sensor 9 described in the first embodiment, an intermediate member 96 is provided between the first strain generating body 92 and the second strain generating body 92. The intermediate member 96 is an elastic body such as rubber, for example. The intermediate member 96 may be an elongated cylindrical roller, a bearing, or a spring member. The middle member 96 is set to have a Young's modulus and a thickness such that the thickness remains without being completely crushed when the maximum load is applied.

  When a relative displacement occurs between the contact portion between the bank portion 91a of the first strain generating body 91 and the second strain generating body 92 by interposing the intermediate member 96, the deformation in the shear direction of the intermediate member 96 The relative displacement is absorbed by Thereby, the adhesion between the bank portion 91a of the first strain generating body 91 and the intermediate member 96 and the adhesion between the contact surface of the second strain generating body 92 and the intermediate member 96 can be maintained. There is no slippage. In addition, since the intermediate member 96 separates the contact surfaces of the bank portion 91a of the first strain generating body 91 and the second strain generating body 92 and does not make direct contact with each other, no frictional force F is generated.

  According to this embodiment, the effect of absorbing the relative displacement of the contact surface between the bank portion 91a of the first strain generating body 91 and the second strain generating body 92 due to the shear deformation of the intermediate member 96, and the thickness of the intermediate member 96 Thus, the first strain generating body 91 and the second strain generating body 92 are separated to obtain an effect of not generating a frictional force. As a result, the load-strain characteristic of the load sensor 9 can be obtained without hysteresis.

  As described above, the load sensor 9 and the electric brake 1 according to the present embodiment include the strain sensor 93, the first straining body 91 having the strain sensor 93 mounted thereon, and the first straining body 91 in series in the load direction. In the load sensor 9 having the second strain body 92 disposed, the intermediate member 96 is provided between the bank portion 91 a of the first strain body 91 and the second strain body 92.

  According to this, by absorbing the displacement of the bank portion 91a of the first strain generating body 91 by the shear deformation of the intermediate member 96, the hysteresis generated in the load-strain characteristic of the load sensor 9 can be reduced. Can be measured with high accuracy. Further, since the load N can be accurately measured, the braking force control of the electric brake 1 can be set finely, which can contribute to the improvement of the ride quality of the vehicle.

  As mentioned above, although the embodiment of the present invention was explained in full detail, the present invention is not limited to the above-mentioned embodiment, and various designs are possible in the range which does not deviate from the spirit of the present invention described in the claim. It is possible to make changes. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to one having all the described configurations. Further, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Furthermore, with respect to a part of the configuration of each embodiment, it is possible to add / delete / replace other configurations.

Reference Signs List 1 electric brake 2 caliper housing 3 electric motor 4 reduction gear 5 lead screw 6 nut 7 piston 8 brake pad 9 load sensor 91 first straining body 91a bank portion (first support portion)
91b Pressure receiving unit (first input unit)
92 second strain generating body 92a bank portion (second support portion)
92b Support surface (second input part)
92c Contact surface (second support)
93 strain sensor (first strain sensor)
94 relay board 95 wiring 96 intermediate member 10 disc N load μ friction coefficient F friction force

Claims (6)

A first strain sensor,
A first strain generating body on which the first strain sensor is mounted;
A second strain body arranged in series in a load direction with respect to the first strain body;
A load sensor comprising
The first strain generating body has a first input portion to which a load is input toward the second strain generating body along the load direction, and a direction intersecting the load input direction from the first input portion And a pair of first support portions disposed at mutually separated positions and facing the second strain body.
The second strain generating body has a second input portion to which a load is input toward the first strain generating body along the load direction, and an intersection that intersects the load direction from the second input portion. A load sensor comprising: a pair of second support portions arranged at mutually separated positions in a direction and facing the first strain generating body and respectively contacting the pair of first support portions.   The second input unit is configured by a support surface that protrudes one step higher on the surface opposite to the surface on which the second support portion of the second strain generating body is provided. The load sensor according to 1.   The load sensor according to claim 1, further comprising a second strain sensor mounted on the second strain generating body.   The first strain generating body and the second strain generating body have the same shape, and are arranged so as to be plane-symmetrical. The load sensor according to one item.   The load sensor according to any one of claims 1 to 4, wherein an intermediate member is provided between the first support portion and the second support portion. An electric brake using the load sensor according to any one of claims 1 to 5.

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