JP2007083848A - Steering system for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve practical use of a steering system having a function capable of changing a ratio of a steered quantity of a steered device relative to an operation quantity of a steering operation member. <P>SOLUTION: In this steering system, a variable action transmitting device 14 which can change a relative operation quantity of first elements 82, 180 connected to a steering operation member and second elements 90, 182 connected to a steered device 12 corresponding to drive quantities of third elements 184, 186, 152 engaged with them, is provided with a third element action banning device 200 capable of banning the action of the third elements. Under a condition that the action of the third elements is allowed, the third element action banning device 200 is controlled to intermittently ban the action of the third elements. Accordingly, under a condition that the action of the third elements is allowed, for example, when a drive source 150 of the variable action transmitting device 14 is failed, the ratio of the steered quantity relative to the operation quantity of the operating member can be changed, so as to enable appropriate steering. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a steering system provided in a vehicle, and more particularly to a steering system having a function capable of changing a ratio of a turning amount of a steering device to an operation amount of a steering operation member.

Today, as a steering system provided in a vehicle, a so-called VGRS (Variable Gear Ratio Steering) function, that is, a steering device for an operation amount of a steering operation member such as a steering wheel (hereinafter sometimes simply referred to as “operation member”). A steering system having a device that can change an operation turning ratio that is a ratio of the amount of turning is studied. The device having the VGRS function generally has a differential mechanism and a drive source. For example, as in the case where the drive source or the like is lost, one element of the differential mechanism driven by the drive source. In a situation where a generally free movement of is permitted, the operation of the operation member may not be transmitted to the steering device. In view of this, the devices having the VGRS function described in Patent Documents 1 and 2 listed below prohibit operation of one element of the differential mechanism driven by the drive source by the lock mechanism, thereby controlling operation. The structure is such that the operation of the operation member is transmitted to the steering device in a state where the steering ratio is a fixed value.
JP 2000-62632 A JP 2004-114857 A

  The system described in Patent Document 1 assists the steering force according to the difference between the operation steering ratio before operating the lock mechanism and the fixed ratio that is the operation steering ratio after operating the lock mechanism. By changing the driving force for the power steering function, it is possible to reduce the uncomfortable feeling caused by the change in the operation steering ratio before and after the operation of the lock mechanism. Yes. However, the system described in Patent Document 1, including the system described in Patent Document 2, has a problem that proper steering cannot be performed because the operation turning ratio is fixed by a lock mechanism. This problem is one of the problems of a steering system having a function capable of changing the operation-turning ratio. However, the system having the VGRS function improves the practicality by addressing such a problem. There is plenty of room left. The present invention has been made in view of such circumstances, and an object thereof is to provide a highly practical steering system.

  In order to solve the above-described problems, a vehicle steering system according to the present invention is a third system in which a relative operation amount between a first element coupled to a steering operation member and a second element coupled to a steering device is engaged with them. A steering system including a variable motion transmission device that can be changed according to the driving amount of an element, and realizes intermittent motion transmission from the steering operation member to the steering device in a situation where the operation of the third element is allowed An intermittent motion transmission device is provided.

  According to the vehicle steering system of the present invention, even when the operation of the third element is allowed, for example, when the drive source of the variable motion transmission device is lost, the intermittent motion transmission device is used to switch from the operation member. Since the ratio of the steering amount to the operation amount of the operation member can be changed by intermittently transmitting the operation to the rudder device, appropriate steering is possible. By having such advantages, the vehicle steering system of the present invention is a highly practical system.

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 merely for the purpose of facilitating the understanding of the claimable inventions, and is not intended to limit the combinations of the constituent elements constituting those inventions 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 each of the following items, item (1) is a term indicating a precondition of the vehicle steering system of the claimable invention, and the technical feature of item (11) is added to item (1). Is equivalent to claim 1, the technical feature of (12) is added to claim 1, the claim 2 is added with the technical feature of (3), and claim 2 is added to the technical feature of (3). 3, the technical feature of (13) is added to claim 1, and the technical feature of (6) is added to any of claims 1 to 4 in claim 4. The technical feature of item (7) added to item 5 corresponds to item 5 and corresponds to item 6 respectively.

(1) a steering operation member operated by a driver;
(a) a first element connected to the steering operation member and provided with an operation amount corresponding to the operation amount; and (b) a second element provided relative to the first element. A differential mechanism including an element; and (c) a third element that engages with the first element and the second element; and a drive source that drives the third element. A variable motion transmission device capable of transmitting a motion from the first element to the second element and changing a relative motion amount between the first element and the second element according to a driving amount of the third element;
A vehicle steering system comprising: a steering device that is connected to the second element and realizes steering of a wheel having a steering amount according to an operation amount of the second element;
The vehicle steering system, wherein the variable motion transmission device includes a third element operation prohibiting device capable of prohibiting the operation of the third element.

  As described above, the aspect described in this section is an aspect in which components common to various claimable inventions are listed, and this section has significance as a premise of the claimable invention. In short, the steering system of the aspect of this section is a steering system having a so-called VGRS actuator, and the VGRS actuator is a steering system provided with the lock mechanism described above.

  The configuration of the “steering device” described in this section is not particularly limited, and includes, for example, a steering rod that connects wheels and a mechanism that moves the steering rod in the axial direction. It is possible to employ various configurations already known. As a mechanism for moving such a steered rod, for example, a rack and pinion mechanism, a ball screw mechanism, or the like can be employed.

  The “variable motion transmission device” described in this section is a so-called VGRS actuator in which the relative motion amount between the first element and the second element can be changed depending on a parameter such as a traveling speed of the vehicle. The “differential mechanism” constituting the variable motion transmission device is not particularly limited in its configuration, for example, the first element and the second element are relatively rotated, and the third element is engaged with them. Thus, the mechanism can rotate. Specifically, various mechanisms such as a mechanism in which a bevel gear meshes, a planetary gear mechanism, a harmonic gear mechanism (which may be a two-ring gear type or a cup type), and a cycloid reduction mechanism are adopted. Is possible. Also, as the “drive source”, various drive source devices can be adopted, and for example, an electric motor can be adopted. The housing that accommodates the differential mechanism, the drive source, and the like may be provided fixed to the vehicle body or may be provided so as to be rotatable with respect to the vehicle body. For example, when the system includes a steering device structured to move the steering rod in the axial direction, the former is fixed to the housing of the steering device, or the system can rotate the shaft and the shaft. In the case of including a steering column configured to include a tube to be held in the column, it is possible to employ a column fixed to the steering column. In the latter case, for example, it is possible to adopt a structure in which the housing is fixed to the input shaft of the steering shaft or the steering device, and rotates with the rotation of the input shaft of the steering shaft or the steering device. It is.

  As the “operation amount” in this section, for example, the rotation angle of the steering wheel or some index corresponding thereto can be adopted. As an extreme example, the operation amount of the first element can also be used. is there. In addition, as the “steering amount”, for example, it is possible to adopt a wheel turning angle, a displacement amount of the turning rod, a rotation angle of the input shaft of the turning device, or any index corresponding to any of them. As an extreme example, the operation amount of the second element can be adopted.

  The variable motion transmission device can be controlled by, for example, a control device provided in the system. Specifically, the ratio of the turning amount of the steering device to the operation amount of the steering operation member is changed by changing the relative operation amount of the first element and the second element by controlling the drive source of the variable motion transmission device. It is possible to perform control to change a certain “operation steering ratio”. The operation turning ratio can be set so as to be changed depending on parameters such as the traveling speed of the vehicle, and the control device controls so that the operation turning ratio becomes a setting ratio depending on the parameters. Can be done. Specifically, for example, when the speed of the vehicle is high, in consideration of the running stability of the vehicle, control for reducing the operation turning ratio, or conversely, when the speed of the vehicle is slow, In view of ease and the like, it is possible to perform control to increase the operation steering ratio.

  The variable motion transmission device includes a “third element operation prohibiting device (lock mechanism)” capable of prohibiting the operation of the third element. The configuration of the third element operation prohibiting device is not particularly limited. For example, the third element operation prohibiting device is provided with a locked portion provided in the third element and a locked portion provided in a part of the vehicle body. It is possible to employ a stopper mechanism that has a locking portion that can be stopped and prohibits the operation of the third element in the locked state in which the locked portion is locked by the locking portion. . In addition, for example, a contact member that generates a frictional force that acts as a resistance to the operation of the third element in a state of contact with the third element as described later is provided, and the contact member is brought into contact with the third element. It is also possible to employ a brake mechanism that can suppress and prohibit the operation of the third element.

  The variable motion transmission device has a structure capable of fixing the relative motion amount between the first element and the second element in a state in which the operation of the third element is prohibited. The operation steering ratio is set to a fixed ratio that is fixedly determined. In the aspect of this section, for example, a generally free operation of the third element is allowed due to a failure of the drive source of the variable motion transmission device, a failure of the control system in which no current flows through the drive source, or the like. In this case, the operation of the operation member is not transmitted to the steering device. In that situation, by prohibiting the operation of the third element by the third element operation prohibiting device, it is possible to transmit the operation of the operating member to the steering device according to the fixed ratio.

  However, only by transmitting the operation of the operation member to the steering device according to the fixed ratio, appropriate steering as realized by the variable motion transmission device cannot be performed. Therefore, in order to enable appropriate steering instead of the variable motion transmission device, the aspect of each item shown below realizes intermittent motion transmission from the operation member to the steering device, in other words, A configuration capable of alternately realizing a transmittable state in which motion transmission from the operation member to the steering device is possible and a non-transmittable state in which motion transmission from the operation member to the steering device is substantially impossible; It has become. More specifically, the transmittable state means a state in which the operation of the operation member is transmitted to the steering device according to a fixed ratio, and the non-transmittable state means that the operation is not transmitted to the steering device even if the operation member is operated. This means that the wheels are not steered. By setting it as such a structure, it is possible to change an operation steering ratio arbitrarily from a fixed ratio, and it becomes possible to implement | achieve appropriate steering instead of a variable motion transmission apparatus. In addition, the structure which implement | achieves the intermittent operation | movement transmission is a structure which prohibits the operation | movement of a 3rd element intermittently, for example, between operation members and a steering apparatus in the state which prohibited the operation | movement of the 3rd element. It is possible to adopt a configuration that intermittently releases the connection.

  In the aspect configured to realize the intermittent motion transmission, for example, one of the operation amount and the operation time of the steering operation member in the transmission enabled state and the steering in the transmission disabled state, which will be described in detail later, It is possible to change the operation turning ratio by changing the intermittent operation ratio that is the ratio of the operation amount of the operation member to one of the operation times. Specifically, the intermittent operation ratio is, for example, a so-called duty ratio value that is the ratio of the operation amount of the specified operation member, the operation amount of the operation member that is incapable of transmission within the operation time, and the operation time. It is possible to adopt. If the duty ratio is 0, the operation turning ratio becomes a fixed ratio, and the operation turning ratio becomes smaller than the fixed ratio as the duty ratio is increased from 0. Thus, since the operation steering ratio can be changed to a value smaller than the fixed ratio by changing the intermittent operation ratio, the fixed ratio is a relatively large value within the range of the set ratio depending on a certain parameter. It is desirable that

  In general, even if the operation member is operated, the operation is not transmitted to the steering device and the wheel is not steered, that is, when the operation amount of the operation member that becomes incapable of transmission is large, When the operation time is long, the driver feels uncomfortable because the operation feeling is not obtained. That is, it is desirable that the operation amount and the operation time of the operation member in which the transmission possible state and the transmission impossible state are combined are as small as possible. In other words, it is desirable to increase the number of times of switching between the transmittable state and the untransmittable state before the target turning amount determined with respect to the operation amount of the operation member.

  (2) The steering system performs intermittent operation control for controlling the third element operation prohibiting device so as to intermittently prohibit the operation of the third element in a situation where the operation of the third element is allowed. The vehicle steering system according to item (1), comprising a control device capable of performing the above-described operation.

  The aspect described in this section is an aspect for realizing intermittent motion transmission. In the aspect of this section, the third element operation prohibiting device is controlled to prohibit the operation of the third element and transmit the operation according to the fixed relative operation amount from the first element to the second element. This is a mode in which the prohibition of the operation of the third element is canceled and the non-transmittable state in which the first element and the second element idle are alternately realized. As described above, according to the aspect of this section, the operation turning ratio can be changed, and appropriate steering can be performed. The “situation in which the operation of the third element is allowed” referred to in this section is mainly the third due to the failure of the drive source of the variable motion transmission device, the failure of the control system that cannot supply current to the drive source, or the like. A state is assumed in which the element is allowed to freely move, or a state where the third element is allowed to operate by interrupting the current supply when normal transmission is impossible by the variable motion transmission device.

  (3) A contact member that generates a frictional force that acts as a resistance to the operation of the third element when the third element operation prohibiting device is in contact with the third element, and the contact member contacts the third element The vehicle steering system according to item (2), including an actuator that selectively realizes a state of being in contact and a state of not being in contact.

  The aspect described in this section is an aspect in which the third element operation prohibiting device is limited to the one having a brake mechanism. In the aspect described in this section, for example, the contact member is made to contact the third element by changing the contact area and the contact area, or by providing a damper that attenuates the operation of the contact member with respect to the third element. The frictional force can be gradually increased when contacting the third element, and the contact force can be gradually decreased when separating the contact member from the third element. It is possible to reduce a sense of discomfort to the driver when switching between a state in which the vehicle is not in contact with the vehicle. The “contact member” in this section is not particularly limited. For example, if the contact member has an elastic characteristic, the aspect of this section indicates the distance between the member holding the contact member and the third element. It is possible to change the magnitude of the frictional force by adjusting. Further, by changing the frictional force, it is possible to reduce the uncomfortable feeling at the time of switching. Also, the “actuator” is not particularly limited, and various types such as an electromagnetic solenoid can be adopted.

  In the aspect of intermittently prohibiting the operation of the third element described above, the third element operation prohibiting device switches between the state in which the operation of the third element is prohibited and the state in which the prohibition is released. From the viewpoint of reducing the uncomfortable feeling sometimes given to the driver, the third element operation prohibiting device has a stopper mechanism in which the rapid operation of the third element is prohibited and the prohibition of the operation is suddenly performed. In comparison, it is desirable to have a brake mechanism that can change the magnitude of the frictional force that acts as a resistance to the operation of the third element. That is, the mode described in this section is a mode suitable for a mode in which the operation of the third element is intermittently prohibited.

(4) The steering system is
A connection release device provided between one of the steering operation member and the steering device and one of the first element and the second element to which the steering operation member and the steering device are connected, and capable of releasing the connection therebetween. When,
The third element operation prohibiting device is controlled so as to prohibit the operation of the third element, and between one of the steering operation member and the steering device and one of the first element and the second element. The vehicle steering system according to item (1), further comprising: a control device capable of performing intermittent operation control for controlling the connection release device so as to intermittently release the connection.

  The aspect described in this section is an aspect for realizing intermittent motion transmission. In this mode, the operation of the third element is prohibited, so that the operation is transmitted from the first element to the second element according to a fixed relative movement amount, and between the steering operation member and the first element. , It is an aspect which implement | achieves alternately the transmission possible state which connected the connection cancellation | release apparatus provided in either between the steering apparatus and the 2nd element, and the transmission impossible state which cancel | released connection. As described above, according to the aspect of this section, the operation turning ratio can be changed, and appropriate turning can be performed. The configuration of the “connection release device” in this section is not particularly limited. For example, the “connection release device” has a structure in which a device connected by the interaction between the locking portion and the locked portion is in a locked state. A thing, a clutch mechanism, etc. are employable. By the way, in the aspect of this section, since the connection release device is controlled after the operation of the third element is prohibited, the third element operation prohibition device has a small frictional force between the third element and the contact member. It is desirable to have a stopper mechanism that can prevent the movement of the third element as soon as possible without causing slippage.

  (5) One of the steering operation member and the steering device and one of the first element and the second element are coupled by frictional engagement between engaging portions provided in each of the first element and the second element. And the connection release device places the engagement portions in an engaged state, whereby one of the steering operation member and the steering device, and one of the first element and the second element. The vehicle steering system according to item (4), which is configured to release connection with the vehicle.

  In the aspect described in this section, in the aspect in which the above-described steering system includes the connection release device and the control device, either the steering operation member and the first element, or between the steering device and the second element. It is the aspect which limited the structure of this and the structure of the connection release apparatus which cancels | releases the connection. As the connection release device in this section, for example, a device having a clutch-like structure can be adopted. In this aspect, for example, the frictional force is gradually reduced when the connection of the connected parts is released by changing the force of bringing the engaging parts into contact with each other and the area of contact between them. In addition, it is possible to gradually increase the frictional force at the time of connection, and by adopting such a configuration, it is possible to reduce the uncomfortable feeling to the driver when switching the connection state It is.

  (6) When the control device performs the intermittent operation control, one of an operation amount and an operation time of the steering operation member in a state in which operation transmission from the steering operation member to the steering device is possible; The intermittent operation ratio that is a ratio of the operation amount of the steering operation member to one of the operation times in a state in which the operation transmission from the steering operation member to the steering device is impossible can be changed (Item (2) to) The vehicle steering system according to any one of (5).

  Since the aspect described in this section can change the operation turning ratio by changing the intermittent operation ratio, according to the aspect described in this section, an arbitrary operation turning ratio is realized. It becomes possible. The “intermittent operation ratio” described in this section is, for example, the ratio of the operation amount of the operation member in one of the transmittable state and the non-transmittable state, the operation amount of the other operation member, and the operation time to the operation time. The ratio of the operation amount and the operation time in one of the transmittable state and the non-transmittable state to the total of the operation amount in the transmittable state, the operation amount in the non-transmittable state, and the operation time. It may be a so-called duty ratio value. Note that, as described above, “the state in which the operation cannot be transmitted from the steering operation member to the steering device” means that the operation is transmitted to the steering device even if the operation member is operated. This means that the wheels are not steered.

  (7) When the control device controls the drive source based on a certain parameter, an operation turning ratio that is a ratio of a turning amount of the turning device to an operation amount of the steering operation member is set as the parameter. It is possible to execute the setting ratio control to be the set ratio on which the relied on, and when executing the intermittent operation control, the intermittent operation ratio is set so that the operation turning ratio becomes a ratio corresponding to the setting ratio in the setting ratio control. The vehicle steering system according to item (6), which is configured to be changeable.

  The “setting ratio control” referred to in this section is a control in which the relative operation amount between the first element and the second element is changed by the drive source of the VGRS actuator so that the operation turning ratio becomes the setting ratio described above. Say. According to the aspect described in this section, even after switching from the setting ratio control to the intermittent operation control, the operation turning ratio can be controlled to become the setting ratio. Appropriate turning is possible without giving a sense of incongruity due to the difference in the amount of turning with reference to. The “parameter” referred to in this section can be a value that indicates, for example, a vehicle running state, a vehicle operation state, or the like. By the way, if the intermittent operation ratio at the time of the increase operation and the intermittent operation ratio at the time of the return operation are different, the control delay from the command of switching between the transmission possible state and the non-transmission state to the realization, the aforementioned friction force Due to the mechanical delay until switching between the transmission possible state and the transmission impossible state is caused, there may be a deviation between the neutral position of the operation member and the neutral position of the steering device. In that case, for example, the deviation can be prevented by adjusting the intermittent operation ratio. In addition, when a deviation occurs, the produced deviation can be corrected by adjusting the intermittent operation ratio.

  (8) Each of the first element and the second element includes a circular spline having a different number of teeth and rotates. The third element meshes with both the circular splines. The variable motion transmission device includes a harmonic gear mechanism by including a flex spline and a wave generator on which the flex spline is fitted, and the drive source is a motor that rotates the wave generator. A vehicle steering system according to any one of (1) to (7), comprising:

  The mode described in this section is a mode in which the variable motion transmission device is limited to a harmonic gear mechanism (sometimes referred to as a harmonic drive mechanism (registered trademark) or a strain wave gearing mechanism). Since the harmonic gear mechanism is a compact speed change mechanism including a differential mechanism that can obtain a large reduction ratio, the aspect described in this section realizes a compact steering system.

  (11) In the situation where the operation of the third element is permitted, the steering system transmits the intermittent operation from the steering operation member to the steering device by using the third element operation prohibiting device. The vehicle steering system according to item (1), which includes an intermittent motion transmission realizing device.

  The aspects described in this section are a general concept of the claimable invention. The “intermittent motion transmission realization device” referred to in this section is a general term for means for realizing intermittent motion transmission, and is a general concept of all the modes for realizing intermittent motion transmission described above. In other words, the intermittent motion transmission realization device may be a device that intermittently prohibits the operation of the third element as described above, and includes a connection release device and intermittently releases the connection by the device. You may do.

  (12) The steering system includes a control device capable of executing intermittent operation control for controlling the third element operation prohibiting device so as to intermittently prohibit the operation of the third element, and the intermittent operation transmission realizing device The vehicle steering system according to item (11), including the control device.

  The aspect described in this section can obtain the same effect as the aspect in which the operation of the third element described above is intermittently prohibited. Moreover, it is also possible to employ | adopt the technical feature of each aspect dependent on the aspect.

  (13) The steering system is provided between (A) one of the steering operation member and the steered device, and one of the first element and the second element to which the steering system is connected, and (B) controlling the third element operation prohibiting device so as to prohibit the operation of the third element, and one of the steering operation member and the steering device. And a control device capable of executing intermittent operation control for controlling the connection release device so as to intermittently release the connection between the first element and the second element, and transmitting the intermittent operation. The vehicle steering system according to item (11), wherein the realization device includes the connection release device and the control device.

  The aspect described in this section has the same effect as the aspect in which the connection releasing device described above is provided and the connection by the device is intermittently released. Moreover, it is also possible to employ | adopt the technical feature of each aspect dependent on the aspect.

  Hereinafter, some embodiments of the present invention and modifications thereof will be described in detail with reference to the drawings. In addition to the following examples, the present invention is implemented in various modes including various modes modified and improved based on the knowledge of those skilled in the art, including the mode described in the above [Mode of Invention]. be able to.

<First embodiment>
1. Configuration of Steering System FIG. 1 schematically shows the overall configuration of a steering system that is a first embodiment of the present invention. The steering system is a power steering system, and mainly includes an operating device 10, a steering device 12, a VGRS actuator 14 as a variable motion transmission device, and an electronic control unit 16 (hereinafter referred to as "ECU 16") as a control device. It may be abbreviated), and is configured to include them as components.

  The operation device 10 includes a steering wheel 20 as a steering operation member, and a steering column 22 (hereinafter sometimes simply referred to as “column” 22). The column 22 includes a steering shaft 24 having a steering wheel 20 connected to one end thereof, and a steering tube 26 (hereinafter simply referred to as “tube 26”) as a shaft housing that rotatably holds the steering shaft 24. It is comprised including. The column 26 is fixed to the vehicle body by fixing the tube 26 to the reinforcement of the instrument panel. The shaft 24 is provided with an operation angle sensor 28 that detects an operation angle of the steering wheel 20 as an operation amount of the operation member at a connection portion of the steering wheel 20.

  The steered device 12 is mainly configured by a housing 30 fixed to a vehicle body (specifically, a chassis) and a steered rod 32 provided on the housing 30 so as to be movable in an axial direction (left and right direction of the vehicle). . The steering device 12 has a pinion shaft 34 as an input shaft to which a steering force from the operation device 10 side is input. A rack 38 that meshes with a pinion 36 formed on the pinion shaft 34 is formed on the steered rod 32, and the pinion shaft 34 and the steered rod 32 are connected by a rack and pinion mechanism (see FIG. 2). . With such a structure, the steered rod 32 is moved in the axial direction by the rotation of the pinion shaft 34. Further, both end portions of the steered rod 32 are connected to one end portions of the left and right tie rods 42 via ball joints 40, and the other end portions of the tie rods 42 are connected to the left and right ends via ball joints 44. The steering knuckles 48 that hold the respective steered wheels 46 are connected to the knuckle arm portions 50 of the steering knuckles 48. Furthermore, the steering device 12 includes an assisting mechanism 52 that assists the steering force required to steer the wheels 46, and has a structure that assists the axial movement of the steered rod 32. Although illustration is omitted, a ball screw (male screw) is formed on the steered rod 32, and the steered device 12 includes a ball nut that has a bearing ball in the housing 30 and is screwed into the ball screw. An electric motor for rotating the ball nut is provided, and the movement of the steered rod 32 is assisted by the driving force of the motor. The steered device 12 is provided with a steered amount sensor 54 that detects the amount of movement of the steered rod 32.

  The VGRS actuator 14 is a device that performs the function of transmitting the rotation of the steering shaft 24 that rotates according to the rotation of the steering wheel 20 to the steering device 12. As shown in FIG. 1, the VGRS actuator 14 is fixed to the steering device 12 by fastening its own housing 80 to the housing 30 of the steering device 12. The VGRS actuator 14 includes an input shaft 82, and one end portion that extends from the housing 80 of the input shaft 82 is connected to one end portion of the intermediate shaft 86 through the universal joint 84. The other end of the intermediate shaft 86 is connected to the end of the steering shaft 24 opposite to the steering wheel 20 via a universal joint 88.

  FIG. 2 shows a cross-sectional view of the VGRS actuator 14. The VGRS actuator 14 has a rotation ratio of the rotation of the housing 80, the input shaft 82 provided rotatably with respect to the housing 80, the output shaft 90 provided rotatably with respect to the housing 80, and the input shaft 82. A variable transmission mechanism 92 that transmits to the output shaft 90 in a changeable state is included. The housing 80 is configured by assembling three sub-housings (an upper housing 94, a lower housing 96, and a lock mechanism housing 98). The lower housing 96 is provided with a flange portion 100, and fastening holes 102 are formed in the flange portion 100 at four equally spaced positions on one circumference. The flange portion 100 is attached to the pedestal portion 104 with its flange surface in contact with the pedestal surface of the pedestal portion 104 provided in the housing 30 of the steering device 12. The pedestal portion 104 is provided with four female screw holes 106 at positions corresponding to the fastening holes 102. With the fastening holes 102 and the female screw holes 106 aligned with each other, a bolt 108 serving as a fastening material is used to form a flange. The part 100 and the pedestal part 104 are fastened. In this way, the housing 80 of the VGRS actuator 14 is fixed to the housing 30 of the steering device 12, so that the VGRS actuator 14 is fixed to the steering device 12, and the housing 80 cannot rotate relative to the vehicle body. It is in a provided state.

  The input shaft 82 is configured by integrating an upper shaft 110, a lower shaft 112, and a torsion bar 114. The upper shaft 110 extends from the upper portion of the housing 80, and serrations are formed on the outer periphery of the extending portion. In the portion where the serration is formed, the universal joint 84 is connected, and rotation from the operating device 10 is input. The upper shaft 110 is a stepped hollow, and the lower shaft 112 is inserted into a lower portion having a large diameter portion. A bearing 116 is interposed between the inner peripheral surface of the large-diameter portion of the upper shaft 110 and the outer peripheral surface of the lower shaft 112, so that the upper shaft 110 and the lower shaft 112 can rotate relative to each other. The lower shaft 112 has a flange portion 118 at the lower portion, and a bottomed hole extending in the axial direction from the upper end portion. One end of the torsion bar 114 is serrated to the bottom of the bottomed hole. The other end of the torsion bar 114 is serrated to the upper end of the upper shaft 110. With such a configuration, the input shaft 82 allows the torsion bar 114 to be twisted, and the input shaft 82 itself is twisted accordingly.

  The lower portion of the output shaft 90 is a shaft portion 120, and an annular portion 122 that is formed integrally with the shaft portion 120 and has a larger diameter than the shaft portion 120 is provided on the output shaft 90. The flange portion 118 of the lower shaft 112 that constitutes the input shaft 82 is located along a flange portion that connects the annular portion 122 and the shaft portion 120 of the output shaft 90, and the flange portion 118 is formed on the annular portion 122. It is supposed to be included. The shaft portion 120 is hollow, and the lower end portion of the lower shaft 112 constituting the input shaft 82 is fitted into the upper portion. A bushing 124 is interposed between the outer peripheral surface of the lower end portion of the lower shaft 112 and the inner peripheral surface of the hollow hole of the shaft portion 120 so that the lower shaft 112 and the shaft portion 120 can be rotated relative to each other. Yes. The upper shaft 110 constituting the input shaft 82 is rotatably held by the upper housing 94 via a bearing 126 at the outer periphery thereof, and the shaft portion 120 of the output shaft 90 is supported by the lower housing via the bearing 128 at the outer periphery thereof. 96 is rotatably held.

  A pinion shaft 34 that is an input shaft of the steering device 12 is rotatably provided in the housing 30 via a bush 130 below the pinion 36 and via a bearing 132 above the pinion 36. Serration external teeth 134 are formed on the upper portion of the pinion shaft 34, while serration internal teeth 136 are formed on the lower portion of the shaft portion 120 of the output shaft 90, and the VGRS actuator 14 is connected to the steering device 12. In the attached state, the output shaft 90 and the pinion shaft 34 are serrated. With such a structure, the rotation of the output shaft 90 is transmitted to the pinion shaft 34.

  As described above, the steered rod 32 is held in the housing 30 so as to be movable in the axial direction, and a rack 38 formed on the steered rod 32 is engaged with the pinion 36 of the pinion shaft 34. Yes. A mechanism for backing up the steered rod 32 is provided on the back side of the rack 38 of the steered rod 32. More specifically, a support member 140 that supports the steered rod 32 from behind is disposed in a hole provided in the housing 30, and a cap 142 is screwed to the end of the hole, and the support member 140, the cap 142, By providing a compression coil spring 144 therebetween, the steered rod 32 is backed up in order to ensure proper engagement between the rack 38 and the pinion 36.

  The variable transmission mechanism 92 employs a harmonic gear mechanism. As a power source of this harmonic gear mechanism, the VGRS actuator 14 is provided with a motor 150. A motor shaft 152 that is an output shaft of the motor 150 is hollow, and is disposed in a state where the input shaft 82, specifically, the lower shaft 112 is inserted through the motor shaft 152. Bearings 154 and 156 are interposed between the inner peripheral surface of the motor shaft 152 and the outer peripheral surface of the lower shaft 112, and the motor shaft 152 is held by the lower shaft 112 so as to be relatively rotatable. The housing 80 is rotatable. A plurality of permanent magnets 158 are fixed in the circumferential direction on the outer peripheral portion of the motor shaft 152, and they constitute a rotor of the motor 150. A plurality of pole bodies 160 (in which a coil is wound around a core) are fixedly disposed on the inner surface of the housing 80 so as to face the permanent magnet 158, and each of these pole bodies 160 is a stator pole. As a result, they constitute a stator. With such a structure, the motor 150 is a so-called brushless motor. The rotational position of the motor shaft 152 (also referred to as the rotational angle or rotational phase), that is, the rotational angle position of the rotor is determined by the attachment ring 162 attached to the upper end of the motor shaft 152 and the inner surface of the housing 80. It is detected by a resolver 164 provided therebetween, and is controlled by an unillustrated motor control circuit to switch energization to the pole body 160 in accordance with the rotational angle position of the rotor. Further, the rotation speed of the motor 150 is controlled by using the detection signal of the resolver 164.

  The variable transmission mechanism 92 includes a stator gear 180 as a first circular spline (first ring gear), a driven gear 182 as a second circular spline (second ring gear), a flexible gear 184 as a flex spline that meshes with them, It includes a wave generator 186 as a wave generator that supports the gear 184 and generates a wave.

  FIG. 3 is a schematic diagram of the variable transmission mechanism 92 viewed from the axial direction. The configuration and function of the variable transmission mechanism 92 will be described with reference to this figure as well. The stator gear 180 is a ring gear formed with internal teeth. The stator gear 180 is fixed to the input shaft 82, specifically, the outer peripheral portion of the flange portion 118 of the lower shaft 112, and cannot rotate relative to the input shaft 82. . The driven gear 182 is a ring gear in which internal teeth are formed. The driven gear 182 is fixed to the upper end portion of the inner peripheral portion of the annular portion 122 of the output shaft 90 and cannot rotate relative to the output shaft 90. Furthermore, the stator gear 180 and the driven gear 182 are provided coaxially, the stator gear 180 that is the input side gear is positioned below in the direction of the output side, and the driven gear 182 that is the output side gear is the input. By being located in the upper side, which is the side direction, they are arranged side by side in the axial direction as if they were interchanged. The number of teeth of the stator gear 180 and the number of teeth of the driven gear 182 are different from each other. The stator gear 180 has 102 teeth, whereas the driven gear 182 has 100 teeth. The flexible gear 184 is a ring gear in which external teeth are formed, and is flexible by being relatively thin. The number of teeth of the flexible gear 184 is the same as that of the driven gear. The number of gear teeth may be changed so that the stator gear 180 has 100 teeth and the driven gear 182 has 102 teeth.

  The wave generator 186 functions as a generally elliptical cam, and is configured to include a support disk 188 having a generally elliptical disk shape and a bearing 190 fitted on the outer periphery of the support disk 188. The support board 188 is provided with a shaft hole at its center, and is connected to the motor shaft 152 so as not to be relatively rotatable with the motor shaft 152 fitted in the shaft hole. The bearing 190 is attached to the support plate 188 in a state where the outer periphery of the support plate 188 is fitted into the inner race 192 of the bearing 190. The outer race 194 of the bearing 190 is also relatively thin, so that it has flexibility. The flexible gear 184 is attached to the outer periphery of the bearing 190 so as not to rotate relative to the outer race 194 of the bearing 190. The flexible gear 184 is deformed into an ellipse by the wave generator 186, and meshes with the stator gear 180 and the driven gear 182 at two locations on the major axis of the ellipse, and is completely separated from them at the minor axis. It is said that.

  When the stator gear 180 is rotated in a state where the rotation of the motor shaft 152 is prohibited, the flexible gear 184 circulates along the ellipse while moving the meshing position with elastic deformation together with the outer race 194 of the bearing 190. Accordingly, the driven gear 182 that meshes with the flexible gear 184 also rotates in the same direction as the stator gear 180. Specifically, it rotates at a rotation ratio corresponding to the gear ratio (gear ratio 100/102) between the stator gear 180 and the driven gear 182.

  Consider a case where the motor generator 152 is rotated by rotating the motor shaft 152. First, in order to simplify the explanation, if the stator gear 180 is fixed, when the wave generator 186 is rotated, the flexible gear 184 is elastically deformed and rotates while moving the meshing position. Since the number of teeth of the stator gear 180 and the driven gear 182 is different, an amount of rotational phase difference corresponding to the difference in the number of teeth is generated between the stator gear 180 and the driven gear 182. Specifically, a rotational phase difference of two teeth per one rotation of the wave generator 186 is generated. More specifically, in FIG. 3, if the wave generator 186 is rotated once in the clockwise direction, the driven gear 182 rotates counterclockwise by two teeth with respect to the stator gear 180. Actually, since the stator gear 180 rotates as the input shaft 82 rotates, the rotation ratio of the driven gear 182 to the stator gear 180 is determined by the relative rotation amount between the stator gear 180 and the wave generator 186. That is, if the rotation direction of the stator gear 180 and the rotation direction of the wave generator 186 are the same, the driven gear 182 is decelerated below the gear ratio, that is, the rotation ratio having a value smaller than the rotation ratio corresponding to the gear ratio. So it will be rotated. Conversely, if the rotation direction of the stator gear 180 and the rotation direction of the wave generator 186 are opposite, the driven gear 182 is accelerated more than the gear ratio, that is, a value larger than the rotation ratio according to the gear ratio. It is rotated with a rotation ratio. Note that the degree of acceleration and deceleration depends on the rotational speed of the wave generator 186, and therefore the rotational ratio can be arbitrarily changed by changing the rotational speed of the motor 150. In this way, the variable transmission mechanism 92 transmits the rotation of the input shaft 82 to the output shaft 90 so that the rotation ratio can be changed.

  From the structure as described above, the input shaft 82 provided rotatably in the housing 80 and the stator gear 180 connected to the input shaft 82 function as a first element, and the output shaft provided rotatably in the housing 80. 90 and a driven gear 182 connected to the output shaft 90 function as a second element, and a flexible gear 184 meshing with the stator gear 180 and the driven gear 182, a wave generator 186 mounted on the flexible gear 184, and the generation of the wave The motor shaft 152 or the like to which the device 186 is connected functions as a third element, and a differential mechanism is configured including these three elements. In the state where the rotation of the motor shaft 152 is prohibited, the operation turning ratio, which is the ratio of the moving amount of the turning rod 32 of the turning device 12 to the operation angle of the steering wheel 20, is also between the stator gear 180 and the driven gear 182. The fixed ratio is a fixed value corresponding to the gear ratio 100/102.

  Further, the VGRS actuator 14 as a variable motion transmission device has a motor shaft rotation lock mechanism 200 (hereinafter simply referred to as “lock mechanism 200”) as a third element operation prohibition device capable of prohibiting rotation of the motor shaft 152 constituting the third element. Is sometimes abbreviated as “). The locking mechanism 200 will be described with reference to FIG. 4 which is a sectional view of the locking mechanism 200 (A-A section in FIG. 2). The lock mechanism 200 is wound around the outer periphery of the motor shaft 152, an electromagnetic solenoid 202 as an actuator, a lever 206 that can be rotated around a fixed pin 204 that is fixedly provided on the inner surface of the lock mechanism housing 98. A belt 208 having both ends fixed to the lever 206, and a friction material 210 provided on the surface of the belt 208 on the motor shaft 152 side and having a relatively high friction coefficient. Yes. The friction material 210 generates a frictional force that is a resistance against the rotation of the motor shaft 152 in a state in which the friction material 210 is in contact with the motor shaft 152, and functions as a contact member.

  The lever 206 is urged by a spring 214 provided around the fixed pin 204 so that the tip end 212 on the one end side of the lever 206 rotates in a direction away from the motor shaft 152. In addition, the other end of the lever 206 is connected to the solenoid 202, and the solenoid 202 is excited to rotate the lever 206 in a direction in which the tip end 212 thereof faces the motor shaft 152. Has been.

  When the solenoid 202 is demagnetized, the lever 206 is biased by the spring 214 so as to rotate in a direction away from the motor shaft 152. Since both ends of the belt 208 are fixed to the front end portion 212 of the lever 206 and the rotation shaft of the lever 206, the belt 208 is fixed to the front end portion 212 of the lever 206 by the rotation of the lever 206. The end of 208 is pulled and the motor shaft 152 is tightened. As a result, the frictional material 210 is brought into contact with the motor shaft 152, and the rotation is prohibited by the frictional force. When rotation of the motor shaft 152 is prohibited, as described above, rotation transmission according to the gear ratio (100/102) between the stator gear 180 and the driven gear 182 is performed. Then, the operation of the steering wheel 20 is transmitted so as to be the turning amount of the turning device 12 according to the fixed ratio. Further, when the solenoid 202 is excited, the lever 206 is rotated against the urging force of the spring 214. Then, the belt 208 is loosened with respect to the motor shaft 152, and the friction material 210 is not in contact with the motor shaft 152, or even if it is in contact with the motor shaft 152, a slight frictional force is generated. The rotation of the shaft 152 is allowed.

  A hydraulic damper 220 is disposed between the lever 206 and the lock mechanism housing 98 that houses the lock mechanism 200. Specifically, the damper 220 includes a housing 222 that contains hydraulic fluid, a piston 224 that is fitted in the housing 222 so as to be liquid-tight and slidable therein, and penetrates the piston 224 and has both ends at the housing. And a piston rod 226 extending from 222. The housing 222 is fixed to the lock mechanism housing 98, and one end of the piston rod 226 is connected to the lever 206. The piston 224 is provided with a connection passage 228 for connecting two liquid chambers formed by the piston 224 and the housing 222. With such a structure, when the lever 206 rotates, the piston 224 is moved in the housing 222 along with it, and the hydraulic fluid passes through the connection passage 228, so that resistance to the movement of the piston 224 is exerted. The damping force with respect to the rotation of the lever 206 is generated by the resistance force. That is, between the motor shaft 152 and the friction material 210, they are gradually brought into contact with each other and the frictional force is gradually increased, and they are gradually separated to reduce the frictional force gradually. Thus, the rotation start and the rotation prohibition of the motor shaft 152 are smoothly performed.

  Further, the VGRS actuator 14 includes two resolvers 230 and 232 separately from the resolver 164 described above. The resolver 230 is provided between the upper shaft 110 that fits the upper end portion of the torsion bar 114 and the inner surface of the housing 80, and is a device for detecting the rotational angle position of the upper shaft 110. The resolver 232 is provided between an attachment ring 224 fixed to the outer periphery of the lower shaft 112 that fits the lower end portion of the torsion bar 114 and the inner surface of the housing 80. This is a device for detecting the rotation angle position. From the detection signals of the two resolvers 230 and 232, the relative rotational displacement amount between the upper shaft 110 and the lower shaft 112 can be detected as the relative displacement amount between the upper end portion and the lower end portion, and the relative rotational displacement amount. Based on this, the operating force (specifically, operating torque) of the steering wheel 20 is estimated. The operation direction of the steering wheel 20 can also be estimated from the detection signals of these resolvers 230 and 232.

2. Control by ECU The present steering system configured as described above is controlled by the ECU 16. The ECU 16 is mainly composed of a computer. The ECU 16 includes the operation angle sensor 28, the turning amount sensor 54, the resolvers 164, 230, and 232 described above, and the wheel speed sensor 240 (shown in FIG. 1) provided on each wheel. , Only those provided for one wheel 46 are shown). Further, the ECU 16 is connected to the motor of the assist mechanism 52 of the steering device 12, the motor 150 of the VGRS actuator 14, and the solenoid 202 of the lock mechanism 200 via respective drive circuits (drivers). It is supposed to control the operation.

i) Control in the normal state The ECU 16 mainly performs two controls in the normal state. One of the controls is control related to the variable transmission mechanism 92 included in the VGRS actuator 14 described above. As described above, the VGRS actuator 14 has the variable transmission mechanism 92 that changes the rotation ratio of the output shaft 90 with respect to the rotation of the input shaft 82, and the steering wheel 20 is changed by changing the rotation ratio. Control is performed to change the operation turning ratio, which is the ratio of the movement amount of the turning rod 32 to the operation angle. Specifically, the ECU 16 estimates the traveling speed of the vehicle based on the wheel speed detected by the wheel speed sensor 240 provided on each wheel, and the operation turning ratio is set based on the estimated speed. The set ratio control for controlling the variable transmission mechanism 92 (specifically, the rotation direction and rotation speed of the motor 150) is performed so that the ratio becomes equal. Specifically, the set ratio is determined such that the operation turning ratio according to the vehicle speed v can be changed as shown by the solid line in FIG. Incidentally, the alternate long and short dash line in the figure is the fixed ratio of the operation turning ratio according to the fixed gear ratio (100/102) between the stator gear 180 and the driven gear 182 described above. As can be seen from this figure, the steered amount of the steered wheels 46 with respect to the operating angle of the steering wheel 20 is increased by setting the operation steered ratio to increase as the vehicle traveling speed decreases. The ease of operation can be improved. Conversely, by setting the operation turning ratio to be smaller as the traveling speed of the vehicle becomes higher, the steering amount of the wheel 46 with respect to the operation angle of the steering wheel 20 is reduced, and the vehicle travels faster. In this case, the running stability of the vehicle can be improved.

  Another control in the ECU 16 is a control related to the assist mechanism 52 of the steering device 12 described above. The ECU 16 estimates the operation torque as the operation force applied to the steering wheel 20 based on the relative rotational displacement amount between the upper end portion and the lower end portion of the torsion bar 114 detected by the resolvers 230 and 232, and the estimated The assist mechanism 52 (specifically, the energy applied to the electric motor) is controlled so as to exhibit the assist force according to the operation torque.

ii) Intermittent operation control Next, consider a case where the function of the motor 150 of the VGRS actuator 14 has failed. When disconnection or the like is caused, relatively free rotation of the motor shaft 152 is allowed. In that case, in the variable transmission mechanism 92, free rotation of the wave generator 186 is allowed, and therefore appropriate rotation transmission between the stator gear 180 and the driven gear 182 is not performed. In this case, the ECU 16 changes the operation turning ratio by intermittent operation control instead of the set ratio control. This intermittent operation control is control for intermittently prohibiting the rotation of the third element by the lock mechanism 200 which is the third element operation prohibiting device. Specifically, the solenoid 202 is demagnetized to rotate the motor shaft 152. Is a control that alternately realizes a transmittable state that is a state in which the motor shaft is prohibited and a non-transmittable state that is a state in which the rotation of the motor shaft 152 is permitted by exciting the solenoid 202. Further, this intermittent operation control is performed by changing the intermittent operation ratio, which is the ratio of the operation angle δ ₁ of the steering wheel 20 in the transmittable state and the operation angle δ ₂ of the steering wheel 20 in the non-transmittable state. This is a control to change the ratio. In the present embodiment, the intermittent operation ratio is a duty ratio (δ ₂₎ which is a ratio of the operation angle δ ₂ in the non-transmittable state to the sum of the operation angle δ ₁ in the transmittable state and the operation angle δ ₂ in the non-transmittable state. / (Δ ₁ + δ ₂ )), and the ECU 16 duty-controls the supply current to the solenoid 202 so that the ratio is obtained.

  The duty ratio does not give a sense of incongruity to the driver's operation due to a sudden change in the steering amount based on the operation angle of the operation member due to a change in control before and after the failure. To be changed. FIG. 6 schematically shows the relationship between the operation angle of the steering wheel 20 and the turning amount of the turning device in the intermittent operation control. The one-dot chain line shown in the figure is for the case where the operation of the steering wheel 20 is transmitted to the steering device according to the fixed ratio, and the broken line is for the case where the operation is transmitted according to the set ratio set for a certain vehicle speed. is there. When the intermittent operation control is executed so that the set ratio with respect to a certain vehicle speed is obtained, the steered amount with respect to the operation amount is as shown by a solid line in the figure. By the way, in this figure, it is shown that the switching between the transmittable state and the non-transmittable state is performed instantaneously, and in this solid line, the part having the same gradient as the one-dot chain line is the transmittable state, and the gradient The portion where is 0 is incapable of transmission. Actually, the switching between the transmission enabled state and the transmission disabled state is gradually performed by the damper 220, and FIG. 7 shows the relationship between the operation angle and the turning amount when actually controlled by the ECU 16. By performing the control as shown in FIG. 7, the rotation start and the rotation inhibition of the motor shaft 152 are smoothly performed, so that it is possible to reduce the uncomfortable feeling experienced by the driver at the time of switching.

As can be seen from FIGS. 6 and 7, as the duty ratio is set to a value close to 0, for example, the operation angle δ ₁ in the transmittable state is increased with respect to the operation angle δ ₂ in the transmittable state, the operation shift is increased. The rudder ratio can be a value close to a fixed ratio. Conversely, the closer the duty ratio is to 1, for example, the smaller the operation angle δ ₁ in the transmittable state relative to the operation angle δ ₂ in the untransmittable state, the smaller the operation turning ratio is. Can do. In addition, the smaller the operation angle (δ ₁ + δ ₂ ), which is the sum of the operation angle δ ₁ in the transmission possible state and the operation angle δ ₂ in the non-transmission state, the smaller the actual turning amount setting ratio. The deviation from the steered amount becomes smaller, and the operation feeling given to the driver can be made more appropriate.

  From the above, the steering system of the present embodiment is configured to include a control device capable of performing intermittent operation control for controlling the third element operation prohibiting device so as to intermittently prohibit the operation of the third element. It is supposed to be equipped with an intermittent motion transmission realization device. That is, in this embodiment, the operation turning ratio can be changed by the intermittent motion transmission realization device, and appropriate steering becomes possible. Note that the intermittent operation ratio may be a ratio between the operation time of the steering wheel 20 in the transmission enabled state and the operation time of the steering wheel 20 in the transmission disabled state.

3. First Modification Note that, instead of the lock mechanism 200 as the third element operation prohibiting device, a lock mechanism 250 included in the steering system as a modification shown in FIG. 8 can be employed. In the lock mechanism 250 shown in the drawing, a friction material 252 as a contact member is fixed to the tip end portion 212 of the lever 206. The lever 206 is urged by a spring 214 provided around the fixed pin 204 so that the tip end portion 212 rotates in a direction toward the motor shaft 152. The other end of the lever 206 is connected to the solenoid 202, and the solenoid 202 is excited to rotate the lever 206 in a direction in which the tip end 212 thereof is separated from the motor shaft 152. It is said that.

  When the solenoid 202 is demagnetized, the lever 206 is biased by the spring 214 so as to rotate in the direction toward the motor shaft 152. As a result, the motor shaft 152 is brought into contact with the friction material 252 and is prohibited from rotating by the frictional force. When the rotation of the motor shaft 152 is prohibited, the rotation transmission according to the gear ratio between the stator gear 180 and the driven gear 182 is performed as described above, and the operation of the steering wheel 20 is performed as described above. The steering amount is transmitted in accordance with the fixed ratio. When the solenoid 202 is energized, the lever 206 is rotated against the urging force of the spring 214, and the friction material 252 is not in contact with the motor shaft 152. Permissible. As in the first embodiment, a hydraulic damper 220 is disposed between the lever 206 and the lock mechanism housing 98, and the motor shaft 152 and the friction material 252 are gradually brought into contact with each other to produce a frictional force. Are gradually increased, and they are gradually separated so that the frictional force is gradually reduced. Thus, the rotation of the motor shaft 152 and the rotation inhibition are smoothly performed. In the steering system of this modification, the same control as in the above embodiment is performed.

4). Second Modification Furthermore, instead of the VGRS actuator 14, it is possible to employ a VGRS actuator 260 provided in a steering system as a modification shown in FIG. FIG. 9 is a cross-sectional view showing a part of the configuration of the VGRS actuator 260 as the variable motion transmission device. The VGRS actuator 260 shown in the figure employs a planetary gear mechanism as a differential mechanism in place of the harmonic gear mechanism. The planetary gear mechanism 262 is formed on the inner peripheral portion of the sun gear 264, three planetary gears 268 that are meshed with the sun gear 264 at three equal positions in the circumferential direction and supported by the carrier 266, and the three planetary gears 268. And a ring gear 270 with which the inner teeth mesh with each other. The sun gear 264 has a rotary shaft 272 connected to the input shaft 82 to form a first element, and the three planetary gears 268 have the output shaft 90 connected to the carrier 266 and the second element. It is what constitutes. The ring gear 270 has external teeth formed on the outer peripheral portion. On the other hand, the VGRS actuator 260 is provided with a motor 280 as a drive source fixed to the housing 80 of the VGRS actuator 260. A pinion 284 is connected to the motor shaft 282 of the motor 280 and meshed with the external teeth of the ring gear 270. With such a structure, the ring gear 270 is rotated by the rotation of the motor 280, and the ring gear 270, the motor shaft 282, and the pinion 284 constitute a third element.

  As in the first embodiment, the VGRS actuator 260 in this modification is transmitted to the output shaft 90 such that the rotation of the input shaft 82 can change the rotation ratio by controlling the rotation direction and rotation speed of the motor 280. Therefore, the operation of the steering wheel 20 is transmitted to the steering device so that the operation steering ratio can be changed. When the rotation of the motor shaft 282 is prohibited, the operation of the steering wheel 20 is transmitted to the steering device 12 according to the fixed ratio of the operation steering ratio.

  Further, the VGRS actuator 260 includes a lock mechanism 290 as a third element operation prohibiting device capable of prohibiting rotation of the motor shaft 282 constituting the third element. The lock mechanism 290 has a structure like a so-called electromagnetic clutch, and opposes two metal disks 292 and 294, a plurality of electromagnets 296 provided on the disk 292, and the disk 294 of the disk 292. And a friction material 298 fixed to the surface. The disk 292 is fixed to the end of the motor shaft 282 extending upward from the motor 280. On the other hand, a hydraulic damper 220 having the same configuration as that of the first embodiment is fixed to the housing 80 of the VGRS actuator 260, and another disk 294 is fixed to one end portion of the piston rod 226 of the damper 220. Has been. The disk 294 is urged in a direction toward the disk 292 by a spring 300 provided between the upper surface of the disk 294 and the housing 222 of the damper 220.

  When the electromagnet 296 is not energized, the disk 294 is urged by the spring 300 in the direction toward the disk 292. As a result, the disk 292 and the disk 294 are brought into contact with each other via the friction material 298, and the rotation of the disk 292 fixed to the motor shaft 282 is prohibited by the frictional force. When the rotation of the motor shaft 282 is prohibited, as described above, the operation of the steering wheel 20 is transmitted so as to become the turning amount according to the fixed ratio. In addition, when the electromagnet 202 is energized, the disk 294 is moved against the biasing force of the spring 300 so that the disk 292 and the disk 294 are not in contact with each other, and the rotation of the motor shaft 282 is allowed. Is done. As in the first embodiment, the damper 220 causes the disk 292 and the disk 294 to gradually come into contact with each other to gradually increase the friction force, and gradually releases them to gradually reduce the friction force. Thus, the rotation start and the rotation inhibition of the motor shaft 282 are smoothly performed. In the steering system of this modification, the same control as in the above embodiment is performed.

<Second embodiment>
FIG. 10 schematically shows the overall configuration of the steering system of the second embodiment. Since the steering system of the present embodiment has many parts that have substantially the same configuration as the system of the first embodiment, in the description of the present embodiment, the same components as those of the system of the first embodiment are the same. The reference numerals are used to indicate that they correspond, and the description thereof will be omitted or simplified.

  As in the first embodiment, the steering system can be roughly divided into an operation device 10, a steering device 12, a VGRS actuator 14 as a variable motion transmission device, and an ECU 16 as a control device. , Including them as components. However, the housing 80 of the VGRS actuator 14 is fixed to the end of the tube 26 of the operating device 10 on the vehicle front side, the input shaft 82 is connected to the steering shaft 24, and the output shaft 90 is connected to the universal joint 88. And is connected to one end of the intermediate shaft 86. The other end of the intermediate shaft 86 is connected to a pinion shaft 34 that is an input shaft of the steering device 12 via a universal joint 84.

  The intermediate shaft 86 includes an operation device side member 350 whose one end is coupled to the output shaft 90 of the VGRS actuator 14, and a steering device side member 352 whose one end is coupled to the pinion shaft 34 of the steering device 12. The other end of the operating device side member 350 and the other end of the steering device side member 352 are connected by an electromagnetic clutch 354. The electromagnetic clutch 354 is structured to release the connection between the operation device side member 350 and the steering device side member 352 when excited. That is, the steering system of the present embodiment includes a connection release device that is provided between the steering device 12 and the second element of the VGRS actuator 14 and that can release the connection therebetween. .

  Although the steering system of the present embodiment is also controlled by the ECU 16, the control in the normal state is the same as that of the first embodiment, so that the description thereof will be omitted and the intermittent operation control will be described. In the intermittent operation control in the system of the present embodiment, when the motor shaft 152 is allowed to rotate relatively freely, the third element operation prohibiting device prohibits the rotation of the third element. The third element operation prohibiting device can employ each of the lock mechanisms shown in the first embodiment and its modifications, and has an annular shape fixed to the outer periphery of the motor shaft 152. A lock holder formed on the housing 80 and having a locking claw formed on the housing 80, and engaging the locking claw of the lock lever with a recess provided on the lock holder. It is also possible to employ a stopper mechanism that prohibits rotation. If the rotation of the third element is prohibited, the ECU 16 then performs control so that the connection between the steering device 12 and the VGRS actuator 14 is intermittently released by the electromagnetic clutch 354. Specifically, the transmission impossible state, which is a state in which the electromagnetic clutch 354 is excited and released, and the transmission state, which is a state in which the electromagnetic clutch 354 is demagnetized, are alternately realized. From the above, the steering system according to the present embodiment controls (A) the above-described disconnection device and (B) the third element operation prohibiting device so as to prohibit the operation of the third element, and the steering device. And a control device capable of performing an intermittent operation control for controlling the connection release device so as to intermittently release the connection between the second element and the second element. It is. That is, also in the present embodiment, similarly to the first embodiment, the operation turning ratio can be changed by the intermittent operation transmission realization device, and appropriate steering can be performed.

1 is a schematic diagram illustrating an overall configuration of a vehicle steering system according to a first embodiment. It is sectional drawing of the variable motion transmission apparatus shown in FIG. It is the schematic diagram of a harmonic gear mechanism seen from the axial direction. It is sectional drawing (AA cross section in FIG. 2) of the VGRS actuator which shows the 3rd element operation | movement prohibition apparatus in FIG. It is a figure which shows roughly the relationship between the travel speed of a vehicle, and an operation steering ratio. It is a figure which shows roughly the relationship between the operation amount of the operation member in intermittent operation control, and the turning amount of a turning apparatus. It is a figure which shows the relationship between the operation amount of an operation member when the control is actually performed by intermittent operation control, and the turning amount of a turning apparatus. It is sectional drawing of the VGRS actuator which shows the 3rd element operation | movement prohibition apparatus with which the steering system for vehicles as a modification of 1st Example is provided. It is sectional drawing which shows a part of VGRS actuator with which the steering system for vehicles as another modification of 1st Example is provided. It is a schematic diagram which shows the whole structure of the steering system for vehicles of 2nd Example.

Explanation of symbols

10: Operation device 12: Steering device 14: VGRS actuator (variable motion transmission device) 16: Electronic control unit (control device) 20: Steering wheel (steering operation member) 82: Input shaft (first element) 90: Output shaft (Second element) 92: Variable transmission mechanism (harmonic gear mechanism) 150: Motor (drive source) 152: Motor shaft (third element) 180: Stator gear (first element) 182: Driven gear (second element) 184: Flexible Gear (third element) 186: Wave generator (third element) 200: Motor shaft rotation lock mechanism (third element operation prohibiting device) 202: Electromagnetic solenoid (actuator) 210: Friction material (contact member) 220: Damper 250: Lock mechanism (third element operation prohibiting device) 252: Friction material (contact member) 260: VGRS Couture (variable motion transmission device) 262: Planetary gear mechanism (differential mechanism) 264: Sun gear (first element) 268: Planetary gear (second element) 270: Ring gear (third element) 280: Motor (drive source) 282: Motor Shaft (third element) 284: Pinion (third element) 290: Lock mechanism (third element operation prohibiting device) 294: Disk (contact member) 354: Electromagnetic clutch

Claims (6)

A steering operation member operated by the driver;
(a) a first element connected to the steering operation member and provided with an operation amount corresponding to the operation amount; and (b) a second element provided relative to the first element. A differential mechanism including an element; and (c) a third element that engages with the first element and the second element; and a drive source that drives the third element. A variable motion transmission device capable of transmitting a motion from the first element to the second element and changing a relative motion amount between the first element and the second element according to a driving amount of the third element;
A vehicle steering system comprising: a steering device that is connected to the second element and realizes steering of a wheel having a steering amount according to an operation amount of the second element;
The variable motion transmission device includes a third element operation prohibiting device capable of prohibiting the operation of the third element,
An intermittent motion transmission realization device that realizes intermittent motion transmission from the steering operation member to the steered device using the third element motion prohibition device in a situation where the operation of the third element is allowed. Vehicle steering system equipped with.   The steering system includes a control device capable of executing an intermittent operation control for controlling the third element operation prohibiting device so as to intermittently prohibit the operation of the third element, and the intermittent operation transmission realizing device includes: The vehicle steering system according to claim 1, comprising a control device.   A contact member that generates a frictional force that acts as a resistance to the operation of the third element when the third element operation prohibiting device is in contact with the third element; and a state in which the contact member is in contact with the third element; The vehicle steering system according to claim 2, further comprising an actuator that selectively realizes a non-contact state.   The steering system is provided between (A) one of the steering operation member and the steering device and one of the first element and the second element to which the steering system is connected, A connection release device capable of releasing the connection; and (B) controlling the third element operation prohibition device so as to prohibit the operation of the third element, and one of the steering operation member and the steering device, A control device capable of performing intermittent operation control for controlling the connection release device so as to intermittently release the connection between one of the first element and the second element; The vehicle steering system according to claim 1, comprising the connection release device and the control device.   When the control device performs the intermittent operation control, one of an operation amount and an operation time of the steering operation member in a state in which operation transmission from the steering operation member to the steering device is possible, and the steering operation 5. The intermittent operation ratio, which is a ratio between the operation amount of the steering operation member and one of the operation times in a state in which the operation cannot be transmitted from the member to the steering device, can be changed. The vehicle steering system according to any one of the above.   The control device controls the drive source based on a certain parameter, so that the operation turning ratio, which is the ratio of the turning amount of the turning device to the operation amount of the steering operation member, depends on the parameter. The ratio setting ratio control can be executed, and when the intermittent operation control is executed, the intermittent operation ratio can be changed so that the operation turning ratio becomes a ratio corresponding to the setting ratio in the setting ratio control. The vehicle steering system according to claim 5 configured.

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