JP2015013548A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power steering device which can alleviate a steering operation burden on an operator, which does not tire out the operator too much and which does not require high skill from the operator.SOLUTION: A power steering device includes: a stub shaft 10 rotated according to an operation of a steering wheel 1 by an operator; a worm shaft 60; and a torsion bar 11 rotationally coupling the stub shaft 10 and the worm shaft 60. The power steering device performs power assist of the steering of a vehicle by controlling hydraulic oil of predetermined pressure by a hydraulic control valve 80 based on relative positional deviation in a rotation direction occurring between the hydraulic control valve 80 and a sleeve 70 according to torsion of the torsion bar 11. The sleeve 70 and the worm shaft 60 are configured separately, so that the relative positional deviation in the rotation direction of the sleeve 70 with respect to the worm shaft 60 can be controlled.

Description

  The present invention relates to a power steering apparatus that assists a driver's steering (handle) operation for steering a vehicle with an actuator.

  Conventionally, for example, as described in Patent Document 1, Patent Document 2, and the like, in a vehicle (automobile) such as a truck or a bus, in the middle of a mechanism that steers the steering wheel of the vehicle according to the operation of the driver, Various power steering devices that assist the steering force necessary for steering the vehicle and reduce the burden on the driver (heavy steering operation) by applying the output of a hydraulic actuator or electric motor, etc. It has been proposed (Patent Document 1, Patent Document 2).

JP 2006-312411 A JP 2007-320333 A

  By the way, when there is a disturbance such as a street rudder or a cross wind while the vehicle is traveling, there is a risk that traveling stability such as straight traveling may be impaired particularly during high-speed traveling. As a result, it is necessary for the driver to repeat the correction steering operation in order to maintain traveling stability such as straightness, especially in trucks and buses where traveling for a relatively long time is often performed. There is a risk of fatigue.

  In addition, there is play (a region where the operation is not transmitted as the steering amount of the steering wheel even if the steering wheel is turned) between the driver's steering operation and the actual steering wheel of the vehicle being steered. The correction steering operation as described above has a situation that skill is required.

  In other words, the driver needs to perform corrective steering operation in a direction that converges disturbance of running stability due to disturbance and at an appropriate timing. The steering operation may be transmitted as steering of the steered wheel at a timing at which the timing is shifted or the timing is shifted to promote disturbance. However, in trucks, buses, and the like that become longer (that is, where there is a relatively large amount of play), there is a situation that the driver is required to be highly skilled.

  The present invention has been made in view of such circumstances, and can reduce the steering operation burden on the driver while having a relatively simple and low-cost configuration. An object of the present invention is to provide a power steering device that does not require the above.

For this reason, the power steering apparatus according to the present invention is
A stub shaft that is rotated in response to a driver's steering wheel operation for steering the vehicle;
A worm shaft provided coaxially with the stub shaft;
A torsion bar that coaxially connects the stub shaft and the worm shaft;
With
Relative in the rotational direction generated between the hydraulic control valve provided on the stub shaft side and the sleeve provided on the worm shaft side corresponding to the hydraulic control valve in accordance with the torsion of the torsion bar A power steering device configured to power-assisted steering of a vehicle by controlling hydraulic oil of a predetermined pressure by the hydraulic control valve based on a slight misalignment,
The sleeve and the worm shaft are configured separately, and a relative positional shift in the rotation direction of the sleeve with respect to the worm shaft is configured to be controllable.

  In the present invention, the control of the relative displacement in the rotational direction of the sleeve with respect to the worm shaft may be performed using an electric motor.

  In the present invention, a pinion gear is attached to the output rotation shaft of the electric motor, and the sleeve is rotated by the pinion gear, thereby controlling a relative positional deviation in the rotation direction with respect to the worm shaft. it can.

  According to the present invention, it is possible to reduce the burden of steering operation on the driver while having a relatively simple and low-cost configuration, and thus power that does not require high skill from the driver with less fatigue. A steering device can be provided.

1 is a schematic overall configuration diagram for explaining a steering mechanism including a power steering device according to an embodiment of the present invention. It is sectional drawing which cut | disconnected the power steering apparatus which concerns on embodiment same as the above along a stub shaft and a worm shaft. It is explanatory drawing explaining the supply control of the hydraulic fluid of the predetermined pressure by the spool valve (hydraulic control valve) in the power steering apparatus which concerns on embodiment same as the above. It is an enlarged view which extracts and shows the structure which performs the rotational drive of the sleeve by the electric motor in the power steering apparatus which concerns on embodiment same as the above. It is the figure which looked at the relationship between the worm shaft and the sleeve in the power steering device which concerns on embodiment same as the above from the axial direction. It is a flowchart for demonstrating the correction steering control (relative displacement control in the rotation direction of the sleeve by an electric motor) in the power steering apparatus which concerns on embodiment same as the above. It is sectional drawing which shows one structural example of the electromagnetic clutch arrange | positioned between the electric motor and pinion gear in the power steering apparatus which concerns on embodiment same as the above.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the embodiments described below.

  As shown in FIG. 1, a power steering device 100 according to the present embodiment is connected to a stub shaft 10 that is rotationally connected to a steering wheel (handle) 1 that is operated for steering by a driver. An operation is input, and the driver's operation is power-assisted in the power steering device 100 and output to a pitman arm (swinging arm) 200 attached to the center shaft 20. The movement of the (swinging arm) 200 is transmitted to a steered wheel (not shown) via a drag link 210 and a knuckle arm (not shown), and the steered wheel of the vehicle is steered. Yes.

  As shown in FIG. 2, the power steering apparatus 100 includes a pinion gear 21 attached (fixed) to the outer periphery of the center shaft 20 and a rack gear 30 that meshes with the pinion gear 21. 30 is formed integrally with a piston 40 that is fitted into the cylinder 50 so as to be slidable in the left-right direction in FIG.

  A worm shaft 60 is engaged with the inside of the piston 40 via a ball nut engagement or the like, and a sleeve 70 is attached (fixed) to the left end of the worm shaft 60 in FIG.

  A spool valve (hydraulic control valve) 80 disposed on the inner peripheral side of the sleeve 70 is attached to the stub shaft 10 side, and is integrated with the stub shaft 10 and the sleeve 70 (worm shaft 60). ), And is configured to be rotatable.

  Further, a torsion bar 11 is attached to the right side of the stub shaft 10 in FIG. 2 so as to be integrally rotatable via a parallel pin or the like, while the torsion bar 11 is inserted through the inner peripheral side of the worm shaft 60, Near the right end of the torsion bar 11 in FIG. 2, the worm shaft 60 is coupled to the worm shaft 60 via a parallel pin or the like so as to be integrally rotatable.

  In the steering mechanism including the power steering device 100 having such a configuration, when the driver rotates the steering wheel 1, the stub shaft 10 that is rotationally connected to the steering wheel 1 is rotated and connected to the stub shaft 10. The worm shaft 60 is rotated through the torsion bar 11. At this time, since the worm shaft 60 side becomes rotational resistance, the torsion bar 11 is twisted. As a result, the spool valve 80 substantially integrated with the torsion bar 11 side rotates relative to the sleeve 70 substantially integrated with the worm shaft 60 side. Thus, the relative rotational direction position (rotational angle position) of both of them is shifted.

  As described above, when the spool valve 80 is rotated relative to the sleeve 70, the oil passage area or the oil passage to the cylinder chamber 50 </ b> A (50 </ b> B) is switched, thereby pushing the piston 40. The magnitude of the force (hydraulic pressure) or the direction of the force (hydraulic pressure) pushing the piston 40 is changed (controlled).

  The force that pushes the piston 40 assists the driver's force to rotate the steering wheel 1 and the pitman arm (swinging arm) 200 attached to the center shaft 20, the drag link 210, the knuckle arm, and the like. Thus, the steering wheel of the vehicle can be steered while reducing the driver's steering operation burden (heavy steering wheel operation).

  When the vehicle is traveling straight (when steering is not performed), the torsion bar 11 is not twisted, so the worm shaft 60 (sleeve 70) and the stub shaft 10 (spool valve 80). ) And a relative displacement in the rotational direction does not occur.

  For this reason, as shown in FIG. 3, the spool valve 80 is in an intermediate position of the sleeve 70, and the high-pressure hydraulic oil supplied from the oil pump 300 is returned to the reservoir tank 400 through the clearance, and the cylinder chamber 50A. Since the pressure of (50B) is not increased, the pistons 40 (ball nuts) are not operated because they are in equilibrium with each other.

  On the other hand, when steering in the right (R) direction (or left (L) direction), the torsion bar 11 is twisted, so that the spool valve 80 is relative to the sleeve 70 in the rotational direction. Misalignment (relative displacement) occurs. For this reason, the output port R (or L) connected to the cylinder chamber 50A (or 50B) and the input port IN for high-pressure hydraulic oil supplied from the oil pump 300 communicate with each other. Is supplied to the cylinder chamber 50A (or 50B), the pressure in the cylinder chamber 50A (or 50B) rises, and the cylinder chamber 50B (or 50A) facing the piston 40 is sandwiched. The piston 40 (ball nut) is actuated upward (or downward) in FIG. 3 due to the loss of the balance with the pressure, thereby assisting the driver's force to rotate the steering wheel 1 and pitman arm (swing). (Moving arm) 200, drag link 210, knuckle arm, etc., steered wheels (not shown) are operated to It will be to steer the steering wheel of the vehicle while reducing ring operation bear the (heavy handle operation).

  Here, if there are disturbances such as roadsides or crosswinds during driving, the driving stability such as straight running may be impaired especially during high speed driving. In order to maintain the vehicle, it is necessary to repeat the correction steering operation. In particular, in a truck or a bus that is frequently run for a relatively long time, there is a possibility that the driver's fatigue may progress.

  In addition, there is play (a region where the operation is not transmitted as the steering amount of the steering wheel even if the steering wheel is turned) between the driver's steering operation and the actual steering wheel of the vehicle being steered. The correction steering operation as described above has a situation that skill is required.

  In other words, the driver needs to perform corrective steering operation in a direction that converges disturbance of running stability due to disturbance and at an appropriate timing. The steering operation may be transmitted as steering of the steered wheel at a timing when the timing is shifted or the timing is shifted and the disturbance is promoted. In particular, the vehicle size is large and the steering force is transmitted in the steering mechanism. In trucks and buses where the distance is long (that is, there is a relatively large play, rod expansion and contraction, etc.), there is a situation that a driver needs high skill.

  For this reason, in the power steering device 100 according to the present embodiment, it is possible to reduce the burden of steering operation on the driver, and thus power that does not require high skill from the driver with less fatigue. In order to provide a steering device, the following configuration is adopted.

  That is, in the power steering device 100 according to the present embodiment, the rotation between the worm shaft 60 and the sleeve 70 is performed independently of the driver's operation of the steering wheel 1 (separately or by another route). It was set as the structure which can generate the relative position shift (relative displacement) in a direction.

  Specifically, as shown in FIGS. 3, 4, and 5, the sleeve 70 and the worm shaft are arranged so that the sleeve 70 can be displaced relative to the worm shaft 60 in the rotational direction (relative displacement). The sleeve 70 can be fixed and relatively rotated around the rotation center of the worm shaft 60 so that the relative position shift (relative displacement) can be controlled. An electric motor 90 is provided.

  The electric motor 90 is fixed substantially integrally to the housing side. A pinion gear 91 is attached to the output rotation shaft of the electric motor 90, and the pinion gear 91 is meshed with an outer peripheral gear 71 provided on the outer periphery of the sleeve 70 to rotate the electric motor 90. Thus, the sleeve 70 can be relatively rotated around the rotation center of the worm shaft 60 via the pinion gear 91 and the outer peripheral gear 71.

  In an electronic control unit (ECU) (not shown), information (vehicle traveling information) related to the traveling state of the vehicle (for example, vehicle speed, steering wheel steering angle, actual steering amount of the steering wheel (steering angle), vehicle yaw rate, etc. , Lateral G, etc.), lane deviation information, etc., for example, the driving amount (rotation amount) of the electric motor 90 necessary for converging the disturbance of running stability due to disturbance or the like is obtained by calculation or the like. By driving the electric motor 90 so as to obtain (rotation amount), the pitman arm (swinging arm) 200, dragging, independently of the driver's operation of the steering wheel 1 (separately or by another route) A steered wheel (not shown) can be steered via a link 210, a knuckle arm or the like.

  The lane deviation information is information used to detect a deviation amount (deviation amount) of the vehicle from the traveling lane and control the vehicle so as not to deviate from the traveling lane.

  According to the power steering apparatus 100 according to the present embodiment having the above-described configuration, the correction that has been performed by the driver in the past in the direction in which the disturbance of running stability due to disturbance or the like converges and at an appropriate timing. The steering wheel of the driver is automatically driven by the electronic control unit (ECU) based on information related to the vehicle traveling state (vehicle traveling information), lane deviation information, and the like. Independent of the operation of 1 (separately or by another route), the sleeve 70 is displaced relative to the worm shaft 60 in the rotational direction (relative displacement), so that the correction steering is actually performed. Since it is made to perform, it can implement | achieve high driving | running | working stability in a vehicle, even if there is a disturbance etc., without request | requiring a highly skilled driver | operator.

  Specifically, in the electronic control unit (ECU), for example, a flowchart as shown in FIG. 6 is executed, and instead of the correction steering operation that is conventionally performed by the driver (independent of the driver's steering wheel operation). Then, the correction steering control for converging the disturbance of the running stability due to the disturbance or the like is executed.

That is,
In step (denoted as S in the figure, the same applies hereinafter) 1, white line recognition processing is executed by a CCD camera or the like, and the deviation (lateral deviation) of the vehicle from the white line drawn along the traveling lane is acquired. .

  In S2, it is determined whether or not a deviation (lateral deviation) of a predetermined value or more has occurred based on the deviation (lateral deviation) of the vehicle from the white line. If YES (if the deviation is large), the process proceeds to S3. In the case of NO (when the deviation is small), the process returns to S1.

  In S3, information (vehicle traveling information) related to the traveling state of the vehicle (for example, the steering wheel steering angle, the actual steering amount of the steering wheel (steering angle), changes in these, etc.) is acquired.

  In S4, the information acquired in S3 (for example, the steering wheel steering angle, the actual steering amount (steering angle) of the steered wheels, changes in these, etc.) is attributed to the steering wheel operation of the driver (driver). Determine whether or not.

  In the case of YES, for example, the change of the steering wheel steering angle by the driver corresponds to the change of the actual steering amount (steering angle) of the steered wheels, and the steering operation based on the driver's intention is performed. Assuming that the vehicle is in a closed state, the process returns to S1 without performing the correction steering by the power steering device 100 performed by a route different from the operation of the driver.

  On the other hand, in the case of NO, if the change in the actual steering amount of the steered wheels is relatively large despite the small change in the steering wheel steering angle by the driver, There is no steering operation based on this, and it is determined that there is a reverse input from the steered wheel side such as a disturbance, and the process proceeds to S5 in order to perform correction steering by the power steering device 100 performed on a route different from the driver's operation.

  In S5, information (vehicle traveling information) related to the traveling state of the vehicle (for example, vehicle speed, yaw rate, lateral G, changes thereof, etc.) is acquired.

In S6, it is determined whether or not these are equal to or greater than a predetermined threshold. If the predetermined threshold or more, it is a relatively large reverse input, and there is a risk that the running stability may be lost if the correction steering by the power steering device 100 performed on a route different from the driver's operation is performed. Return to S1.
If it is smaller than the predetermined threshold value, the running state is relatively stable, so that it is permitted to perform the correction steering by the power steering device 100 performed on a route different from the driver's operation, and the process proceeds to S7.

  In S7, drive control of the electric motor 90 is performed so as to eliminate the deviation (lateral deviation) of the vehicle from the white line. In other words, the electronic control unit (ECU) drives and controls the electric motor 90 in place of the correction steering operation that has been conventionally performed by the driver so as to converge the disturbance of running stability due to disturbance or the like. Independently of the operation of the steering wheel 1 (separately or by another route), the sleeve 70 is actually displaced relative to the worm shaft 60 in the rotational direction (relative displacement) to actually move the steering wheel. Steering to correct steering.

  In addition to S7, the electric motor 90 is not driven (the electric motor 90 and the pinion gear 91 and the sleeve 70 are fixed at a predetermined rotational angle position with respect to the worm shaft), and the sleeve by the electric motor 90 is used. Since no relative displacement (relative displacement) in the rotational direction of the worm shaft 60 with respect to the worm shaft 70 is generated, steering by the driver's operation of the steering wheel 1 is performed as in the prior art.

  As described above, according to the present embodiment, the electronic control unit (ECU) automatically determines the occurrence of disturbance in running stability due to disturbance or the like, and instead of the driver, the electronic control unit (ECU) However, since the electric motor 90 is driven and the correction steering is automatically performed so as to converge the disturbance in the running stability such as the disturbance, the structure is relatively simple and low-cost. It is possible to provide a power steering apparatus that can reduce the burden of steering operation on the driver, and that does not require the driver to have high skill with less fatigue.

  In the present embodiment, the electronic control unit (ECU) automatically drives the electric motor 90 based on information related to the traveling state of the vehicle (vehicle traveling information), lane deviation information, and the like. The steering wheel 1 can be steered independently of the driver's operation of the steering wheel 1 (separately or by another route). It is also possible to perform switch-over control for controlling the steering amount to increase, or switch-back control for controlling the driver so that the actual steering amount (steering angle) of the steered wheels is reduced by returning too much steering. is there. In other words, it is possible to realize a so-called variable gear ratio function that varies the actual steering amount of the steered wheels in accordance with the steering operation amount.

  In this embodiment, the pinion gear 91 is rotationally driven by the electric motor 90 disposed in the housing of the power steering apparatus 100, and the sleeve 70 is connected to the worm shaft 60 via the outer peripheral gear 71 meshing with the pinion gear 91. The structure is such that relative rotation (relative displacement) is generated around the center of rotation, and the sleeve 70 and the spool valve 80 (hydraulic control valve) can be controlled by the electric motor 90 with a small output, and the existing hydraulic system is used as it is. Therefore, the cost can be kept low.

  That is, according to the present embodiment, it is possible to reduce the steering operation burden on the driver while having a relatively simple and low-cost configuration, thereby requiring the driver to be highly skilled with less fatigue. It is possible to provide a power steering device without any problems.

  By the way, as shown in FIG. 5 and the like, the sleeve 70 is slidably disposed on the outer periphery of the worm shaft 60 so as to be relatively rotatable. In addition, an uneven engagement portion (stopper portion) X can be provided between the worm shaft 60 and the sleeve 70. With this uneven engagement portion (stopper portion) X, it is possible to avoid the risk that the sleeve 70 will be displaced relative to the worm shaft 60 for a certain reason for a certain amount or more.

  Furthermore, an electromagnetic clutch 92 as shown in FIG. 7 can be interposed between the output rotation shaft of the electric motor 90 and the pinion gear 91.

  For example, when a direct current is applied to the electromagnetic coil 92A, an electromagnetic field is generated and the armature chair 92C is electromagnetically attracted to the drive drive hub 92E with the friction pad 92B, and the torque of the output shaft of the electric motor 90 is changed to the pinion gear 91 side. To be transmitted to

  On the other hand, when the energization of the electromagnetic coil 92A is stopped (when the power is turned off), the electromagnetic field disappears, and the spring disk 92D acts so as to separate the armature chair disk 92C from the drive drive hub 92E. Are separated from the pinion gear 91 side.

  In this way, when the energization to the electromagnetic coil 92A is stopped (the power is turned off), the output shaft of the electric motor 90 and the pinion gear 91 side are separated from each other. When the power is turned off, the output shaft of the electric motor 90 and the pinion gear 91 are separated from each other, so that the fail-safe function is ensured and it is possible to contribute to providing a safer system.

  By providing the electromagnetic clutch 92 in this manner, for example, when a failure such as sticking or runaway occurs in the electric motor 90, the electronic control unit (ECU) determines the control target value (steering amount command value) and The abnormality is determined based on the deviation between the actual steering amount (steering angle) of the steered wheel and the electronic control unit (ECU) determines that there is an abnormality. The clutch 92 is turned off (the rotational connection between the output rotation shaft of the electric motor 90 and the pinion gear 91 is disconnected), so that the rotational driving of the sleeve 70 by the electric motor 90 is stopped, and abnormal steering by the electric motor 90 is performed. By stopping, it is possible to avoid abnormal operation, and thus safety can be maintained high.

  As the electric motor 90, a brushless stepping motor can be employed. Since it is brushless, it is non-contact, excellent in durability and reliability, and since it is a stepping motor, it can control the position (rotation angle) with high accuracy. Therefore, the brushless stepping motor is a power source according to this embodiment. Although it is suitable as the electric motor 90 of the steering device 100, it is also possible to adopt a general electric motor with a brush in consideration of cost and the like.

  The embodiment described above is merely an example for explaining the present invention, and various modifications can be made without departing from the gist of the present invention.

1 Steering wheel (handle)
DESCRIPTION OF SYMBOLS 10 Stub shaft 11 Torsion bar 20 Center shaft 21 Pinion gear 30 Rack gear 40 Piston 50 Cylinder 50A Cylinder chamber 50B Cylinder chamber 60 Warm shaft 70 Sleeve 71 Outer gear 80 Spool valve 90 Electric motor 91 Pinion gear 92 Electromagnetic clutch 100 Power steering device 200 Pitman arm ( Swing arm)
210 Drag link

Claims (3)

A stub shaft that is rotated in response to a driver's steering wheel operation for steering the vehicle;
A worm shaft provided coaxially with the stub shaft;
A torsion bar that rotationally connects the stub shaft and the worm shaft;
With
Relative in the rotational direction generated between the hydraulic control valve provided on the stub shaft side and the sleeve provided on the worm shaft side corresponding to the hydraulic control valve in accordance with the torsion of the torsion bar A power steering device configured to power-assisted steering of a vehicle by controlling hydraulic oil of a predetermined pressure by the hydraulic control valve based on a slight misalignment,
The power steering device according to claim 1, wherein the sleeve and the worm shaft are configured separately, and a relative positional shift of the sleeve with respect to the worm shaft in a rotational direction can be controlled.   2. The power steering apparatus according to claim 1, wherein the relative displacement in the rotation direction of the sleeve with respect to the worm shaft is controlled using an electric motor.   The pinion gear is attached to the output rotation shaft of the electric motor, and the relative displacement in the rotation direction with respect to the worm shaft is controlled by rotating the sleeve with the pinion gear. Power steering device.