JP5246011B2 - Steering device - Google Patents

Description

  The present invention relates to a steering apparatus suitable for application to automobiles such as passenger cars, trucks, and buses.

  Conventionally, as a steering device used in a vehicle, a ball nut type or a rack and pinion type is used, and in particular, when the vehicle is a medium or large size, a ball nut type is often used. In such a ball nut type steering device, there is a problem that a loss of power and energy is large when the hydraulic type is adopted, and a problem that it is difficult to increase the turning force when the electric type is adopted. As a solution, for example, a combination of a hydraulic steering device and an electric steering device as described in Patent Document 1 and sharing the assist force between the hydraulic steering device and the electric steering device has been proposed.

JP 2005-306317 A

  However, in such a steering device, when the torque sensor and the electric assist force generation unit constituting the electric steering device are arranged on the upstream side and the steering wheel side of the control valve constituting the hydraulic steering device, Since the reduction mechanism of the assist force generation unit must be installed on the outer peripheral side of the torsion bar, and the electric motor needs to be installed to protrude further to the outer peripheral side of the input gear of the reduction mechanism, this leads to an increase in the size of the entire steering device. As a result, there arises a problem that the output of the steering force in the electric steering apparatus cannot be increased.

  In view of the above problems, an object of the present invention is to provide a steering device that can increase the output of an electrically driven steering force without causing an increase in size.

In order to solve the above problems, the steering device according to the present invention is:
A first shaft connected to the steering wheel;
A second shaft connected to the first shaft via an elastic body;
A mover extending in the axial direction of the second shaft and having hydraulic pressure receiving surfaces on both sides in the axial direction;
First conversion means for converting the rotational movement transmitted from the first axis to the second axis into the axial movement of the mover;
A hydraulic control means for setting the hydraulic pressure of either one of the hydraulic pressure receiving surfaces on both sides in the axial direction to be higher than the hydraulic pressure of the other in accordance with the relative rotation operation of the first axis with respect to the second axis;
Electric means having a hollow cylindrical rotor disposed on the outer peripheral side of the mover;
It includes a second conversion means for converting the rotational motion of the rotor into the axial motion of the mover.

  The first conversion means and the second conversion means can be constituted by, for example, first and second ball nut mechanisms. A gear that meshes with a sector gear of a sector shaft that is an output shaft of the steering device is formed on the outer peripheral side of the ball nut that constitutes the first ball nut mechanism that is the first conversion means and forms a part of the mover. It is formed.

  Further, the hydraulic control means can be constituted by a combination of a rotary type valve and piping, a casing that liquid-tightly surrounds the movable element, and a liquid chamber defined by a hydraulic pressure receiving surface of the movable element. .

  In addition, the first conversion means is disposed at a position offset in the axial direction with respect to the second conversion means, but the second conversion means is located closer to the steered wheel than the first conversion means. You may arrange | position and you may arrange | position the said 2nd conversion means on the opposite side to the said steering wheel rather than the said 1st conversion means.

  In addition, the steering device may include an electric control unit that controls a driving force of the electric unit in accordance with a relative rotation operation of the first shaft with respect to the second shaft.

  According to the present invention, it is possible to eliminate the necessity of transmitting the rotating operation of the rotor of the electric means to the mover from a speed reduction mechanism combined with gears. It is possible to prevent the size from increasing and to reduce the size, and to increase the output of the turning force by the electric means.

It is a mimetic diagram showing one example of a steering device concerning the present invention. It is a mimetic diagram showing one example of a steering device concerning the present invention. It is a mimetic diagram showing one example of a steering device concerning the present invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing the overall configuration of an embodiment of the steering device 1 of the present embodiment in a cross section including the axial direction.

  As shown in FIG. 1, the steering device 1 of the present embodiment includes a main shaft 2, a hydraulic valve unit 3, a drive unit 4, a hydraulic cylinder unit 5, a gear housing 6, a piston shaft 7, and a sector shaft. 8 is comprised.

  The main shaft 2 includes an upper main shaft 2a on the upper side in FIG. 1, that is, opposite to the sector shaft 8, and a lower main shaft 2b on the sector shaft 8 side. The upper main shaft 2a and the lower main shaft 2b are shafts. Parallel to each other, the lower end side of the upper main shaft 2a and the upper end side of the lower main shaft 2b are connected by a torsion bar 10 so as to be relatively rotatable.

  A steering wheel (not shown) is fitted and connected to the upper side of the upper main shaft 2a in FIG. 1, and the upper main shaft 2a rotates around the axial direction via a bearing 9 on the upper end surface of the gear housing 6. It is supported movably.

  Below, the connection form of the upper main shaft 2a of the main shaft 2 and the lower main shaft 2b and the hydraulic valve part 3 are demonstrated in detail using FIG. FIG. 2 is a schematic diagram showing the main shaft 2 and the hydraulic valve portion 3 which are a part of one embodiment of the steering apparatus 1 of the present embodiment in a cross section including the axial direction.

  As shown in FIG. 2, a press-fitting hole extending in a direction perpendicular to the axial direction is formed on the upper end side of the torsion bar 10, and a fitting hole is formed on the lower end surface of the upper main shaft 2a. A press-fitting hole extending perpendicularly in the axial direction is formed in the vicinity of the upper end surface of the hole, and further, a press-fitting hole is also formed in the vicinity of the upper end surface of the cylindrical valve shaft 12 to form a fitting hole of the upper main shaft 2a. The upper end portion of the torsion bar 10 is fitted, and the inner peripheral surface of the valve shaft 12 is liquid-tightly overlapped with the outer peripheral surface on the lower end side of the upper main shaft 2 a via the O-ring 13. The upper end of the torsion bar 10 is formed by press-fitting the press-fitting pin 11 into the press-fitting hole with the press-fitting hole and the press-fitting hole of the upper main shaft 2a and the press-fitting hole of the valve shaft 12 aligned in the axial direction and the circumferential direction. The lower end of the upper main shaft 2a is connected, the upper main shaft 2a and the valve shaft 12 is connected.

  A press-fitting hole extending in a direction perpendicular to the axial direction is formed on the lower end side of the torsion bar 10, a fitting hole is formed in the upper end surface of the lower main shaft 2b, and a shaft is formed in the vicinity of the lower end surface of the fitting hole. A press-fitting hole extending perpendicularly to the direction is formed, the lower end portion of the torsion bar 10 is fitted into the fitting hole of the lower main shaft 2b, and the inner peripheral surface of the flange 14 is fitted to the outer peripheral surface of the lower main shaft 2b. The flange 14 is also provided with a press-fitting hole extending in a direction perpendicular to the axial direction, and the press-fitting hole of the torsion bar 10, the press-fitting hole of the lower main shaft 2b, and the press-fitting hole of the flange 14 are aligned in the axial direction and the circumferential direction. In this state, the press-fit pin 15 is press-fitted into the press-fit hole, thereby connecting the lower end portion of the torsion bar 10 and the upper end portion of the lower main shaft 2b.

  The outer peripheral surface of the upper end portion of the flange 14 is overlapped with the inner peripheral surface of the lower end portion of the cylindrical valve body 16, and a press-fit hole provided in the vicinity of the upper end surface of the flange 14 and the vicinity of the lower end surface of the valve body 16. The press fitting pin 17 is press-fitted in a state where the press-fitting holes provided in the shaft are aligned with each other in the circumferential direction and the axial direction, whereby the valve body 16 and the flange 14 are connected. 2b.

  A hydraulic port 18 and a hydraulic port 19 are provided on the left side of the gear housing 6 in FIGS. 1 and 2, and the hydraulic port 18 is communicated with a reservoir constituting a hydraulic system (not shown) through an oil path (not shown). An oil passage (not shown) communicates with a pump constituting a hydraulic system (not shown). The pump is driven by being connected to a crankshaft of an engine (not shown), and pressurizes the hydraulic oil stored at atmospheric pressure in a reservoir (not shown) to supply high-pressure hydraulic oil to the hydraulic system.

  1 and 2, a turn port 20 and a turn port 21 are provided on the right side. The turn port 20 is defined between the piston shaft 7 and the gear housing 6 by an oil passage 22 shown in FIG. The turn port 21 is communicated with an upper liquid chamber defined between the piston shaft 7 and the gear housing 6 by an oil passage 23 shown in FIG.

  The valve shaft 12 and the valve body 16 described above are combined to constitute a known rotary valve. When the valve shaft 12 connected to the upper main shaft 2a is rotated relative to the valve body 16 connected to the lower main shaft 2b in the right direction from the neutral position, the hydraulic port 19 and the turn port 20 are communicated with each other. The hydraulic port 18 and the turn port 21 are communicated. When the valve shaft 12 is rotated relative to the valve body 16 in the left direction, the hydraulic port 19 and the turn port 21 are communicated, and the hydraulic port 18 and the turn port 20 are communicated. In the neutral position, the hydraulic port 19 and the hydraulic port 18 communicate with each other.

  An oil seal 24 is provided between the outer peripheral surface of the valve shaft 12 and the inner peripheral surface of the gear housing 6 to prevent the hydraulic oil in the hydraulic valve portion 3 from leaking above the oil seal 24. A seal retaining ring 25 that contacts the upper end surface of the oil seal 24 is further provided above the oil seal 24 on the inner peripheral surface of the gear housing 6 to restrict the upward movement of the oil seal 24.

  An oil seal 26 is provided between the outer peripheral surface of the flange 14 and the inner peripheral surface of the gear housing 6 to prevent the hydraulic oil in the hydraulic valve unit 3 from leaking below the oil seal 26. Further, an oil seal 27 is provided between a partition wall 6a, which is a part of the gear housing 6 between the hydraulic valve unit 3 and the drive unit 4, through which the lower main shaft 2b is inserted, and an outer peripheral surface of the lower main shaft 2b. Is provided.

  The drive unit 4 is accommodated below the partition wall 6 a of the gear housing 6, and a partition wall 6 b that partitions the drive unit 4 and the hydraulic cylinder unit 5 is formed below the drive unit 4. The piston 7 has a bottomed cylindrical part 7a that opens upward, and the bottomed cylindrical part 7a is inserted into the partition wall 6b through an oil seal 28 and supported so as to be slidable in the axial direction.

  A portion of the lower main shaft 2b that protrudes below the partition wall 6a is inserted into the inner peripheral side of the bottomed cylindrical portion 7a that opens above the piston shaft 7, and is located at a lower end portion that is positioned below the partition wall 6b. A first worm shaft 2c is formed in the vicinity, and a thread portion of the first worm shaft 2c is threaded on the first worm shaft 2c in the axial direction of the inner peripheral surface of the bottomed cylindrical portion 7a via a plurality of steel balls. It connects with the 1st ball nut 7b which has a screw part of the shape corresponding to a part. The first ball nut 7b has a ball tube (not shown) that circulates steel balls, and a recirculating ball type first ball nut mechanism 29 is formed by the first worm shaft 2c, a plurality of steel balls, and the first ball nut 7b. Composed.

  The bottom part of the bottomed cylindrical part 7a constitutes a piston part 7c as shown on the lower end side in FIG. 1, and on the upper surface of the piston part 7c, on the inner peripheral side of the bottomed cylindrical part 7a and below the worm shaft 2c. The part located and the part located in the outer peripheral side of the bottomed cylindrical part 7a are connected by the oil path 7d. The upper surface and the lower surface of the piston portion 7c constitute a hydraulic pressure receiving surface.

  A tooth surface 7e is formed in the vicinity of the piston portion 7c of the bottomed cylindrical portion 7a and on the left side in FIG. 1 in the axial direction. The tooth surface 7e is a bottomed cylinder of the piston shaft 7. It meshes with the tooth surface 8a of the sector shaft 8 extending in the direction perpendicular to the shape portion 7a and in the vehicle width direction.

  In the space defined between the partition wall 6a and the partition wall 6b, the stator is positioned on the outer peripheral side of the bottomed cylindrical portion 7a of the lower main shaft 2b and the piston shaft 7 on the inner peripheral surface of the gear housing 6. A fixed motor 30 is provided, and the inner peripheral surface of a hollow cylindrical motor shaft 31 that is drivingly coupled to the rotor of the motor 30 is a second worm formed on the outer peripheral surface near the upper end surface of the piston shaft 7. The second ball nut 31a is configured to have a screw portion corresponding to the screw portion of the shaft 7f, and the second worm shaft 7f and the second ball nut 31a are connected via a plurality of steel balls. The second ball nut 31a has a ball tube (not shown) that circulates steel balls, and a recirculating ball type second ball nut mechanism 32 is formed by the second worm shaft 7f, a plurality of steel balls, and the second ball nut 31a. Composed.

  Further, as shown in FIG. 2, a torque sensor 33 is provided on the outer peripheral side of the upper main shaft 2a, and a torque sensor 34 is provided on the outer peripheral side of the lower main shaft 2b. The outputs of the torque sensor 33 and the torque sensor 34 are input to an EPS ECU (not shown).

  An EPS ECU (Electronic Power Steering Electronic Control Unit) is composed of, for example, a CPU, a ROM, a RAM, a data bus and an input / output interface for interconnecting them, and a torque sensor 33 and a torque sensor 34 according to a program stored in the ROM. Based on the detected steering force of the driver, the driving force generated by the motor 30 of the driving unit 4 is controlled to control the assist force by electric drive.

  At the same time, the sector shaft 8 is connected to a knuckle that rotatably supports a wheel by a pitman arm, a drag link, a tie rod, and a knuckle arm in the case of an axle suspension type, and a pitman arm, a relay rod, It is connected to the knuckle by the idler arm, tie rod, and knuckle arm.

  When a right steering force is input to the steering wheel by the driver, the upper end of the torsion bar 10 is twisted clockwise with respect to the lower end, and the EPS ECU is rotated right by the torque sensor 33 and the torque sensor 34. 1 is detected, the motor 30 of the drive unit 4 is driven, the motor shaft 31 is rotated clockwise, and the piston ball 7 is electrically driven in the axial direction by the second ball nut mechanism 32 in the upward direction in FIG. Further, the valve shaft 12 is rotated clockwise relative to the valve body 16 of the hydraulic valve unit 3, the hydraulic port 19 and the turn port 20 are communicated, and the hydraulic port 18 and the turn port 21 are communicated. Thus, the high-pressure hydraulic fluid from the pump flows into the lower fluid chamber of the hydraulic cylinder section 5, and the hydraulic fluid in the upper fluid chamber is discharged to the reservoir. , Piston shaft 7 is moved upward by the axial moving force due to hydraulic pressure. As a result, the sector shaft 8 is rotated counterclockwise in FIG. 1 to generate both hydraulic and electric assist forces, and the wheels are steered to the right.

  When a leftward steering force is input to the steering wheel by the driver, the upper end of the torsion bar 10 is twisted counterclockwise with respect to the lower end, and the EPSEC is turned leftward by the torque sensor 33 and the torque sensor 34. 1 is detected, the motor 30 of the drive unit 4 is driven, the motor shaft 31 is rotated counterclockwise, and the piston ball 7 is electrically driven in the axial direction toward the lower side in FIG. Further, the valve shaft 12 is rotated counterclockwise relative to the valve body 16 of the hydraulic valve section 3, the hydraulic port 19 and the turn port 21 are communicated, and the hydraulic port 18 and the turn port 20 are communicated. Thus, the hydraulic fluid from the pump flows into the upper fluid chamber of the hydraulic cylinder unit 5, and the hydraulic fluid in the lower fluid chamber is discharged to the reservoir, Ton shaft 7 is moved downward by the axial moving force due to hydraulic pressure. As a result, the sector shaft 8 is rotated clockwise to generate both hydraulic and electric assist forces, and the wheels are steered to the left.

  Of course, in both the right direction and the left direction, the steering force is transmitted to the sector shaft 8 even through the first ball nut mechanism 29. If both the hydraulic pressure and the electric motor fail, the wheel is driven only by the driver's steering force. Is steered.

  In the steering device 1 of the above-described embodiment, the steering wheel corresponds to the steering wheel, the upper main shaft 2a corresponds to the first axis, the torsion bar 10 corresponds to the elastic body, and the lower main shaft 2b corresponds to the second axis. The piston shaft 7 corresponds to the mover, the piston portion 7c corresponds to the hydraulic pressure receiving surface on both sides in the axial direction, and the first ball nut mechanism 29 performs the rotational motion transmitted from the first shaft to the second shaft. Corresponding to a first conversion means for converting the movement of the mover into the axial direction, the hydraulic valve unit 3 is provided with one of the hydraulic receiving surfaces on both the upper and lower sides in the axial direction as the first shaft rotates relative to the second shaft. This corresponds to hydraulic control means for making the hydraulic pressure higher than the other hydraulic pressure, the motor shaft 31 corresponds to the rotor, and the motor 30 is an electric means having a hollow cylindrical rotor disposed on the outer peripheral side of the mover. Applicable Second ball nut mechanism 32 corresponds to the second conversion means for converting the rotational movement of the rotor in the axial movement of the mover, EPSECU corresponds to the electric control unit.

  In the steering apparatus 1 according to the present embodiment as described above, the first ball nut mechanism 29 generates the piston shaft 7 based on the steering force input to the driver's steering wheel. The piston shaft 7 is moved in the axial direction by using both the transmitted axial movement force by electric power and the axial movement force generated by the hydraulic valve portion 3 and the hydraulic piston portion 5 and transmitted to the piston shaft 7. , The sector shaft 8 is rotated to swing a pitman arm (not shown), and a wheel (not shown) can be steered.

  For this reason, the piston shaft 7 has a function of adding an axial driving force by electric power and an axial moving force by hydraulic pressure to combine them into one axial moving force. The point where the directional driving force is synthesized can be the piston shaft 7.

  For this reason, in the prior art, the upper main shaft 2a becomes a point where an electrically driven driving force acts, and the steering force acting on the hydraulic valve 3 is added with the electrically driven driving force, so that the pump of the hydraulic system is constituted. The ratio of assist force generated by hydraulic pressure increases in a region where the load is large and the total assist force generated by the steering device is small, and the degree of freedom of electric assist force cannot be increased. Although there was a problem, the steering apparatus 1 of the present embodiment can solve this.

  That is, since the driving force generated by the drive unit 4 is not added to the steering force transmitted to the upper main shaft 2a, the axial drive force of the hydraulic cylinder unit 5 is changed to the axial drive force of the drive unit 4. The ratio of the assist force generated by the hydraulic cylinder unit 5 is increased in a region where the load of the pump constituting the hydraulic system is increased and the entire assist force generated by the steering device 1 is small. Can be prevented, and the degree of freedom of the assist force by the drive unit 4 can be increased.

  That is, in the hybrid power steering, that is, the HB-PS type steering apparatus 1 according to the present embodiment, the advantages of the control of the electric EPS and the hydraulic HPS are appropriately selected over the entire region of the generated assist force. Therefore, even when the electric drive unit 4 fails, an appropriate assist force can be secured by the hydraulic cylinder unit 5. Conversely, even when the hydraulic system fails, an appropriate assist force can be ensured by the drive unit 4.

  In addition, by adding the assist force by the hydraulic pressure and the assist force by the electric motor and adding them to the piston shaft 7, the upper main shaft 2a and the lower main shaft 2b that are located on the steering wheel side of the piston shaft 7 are added. Therefore, the required strength of the upper main shaft 2a and the lower main shaft 2b can be reduced to reduce the radial dimension and weight.

  Moreover, since the strength required for the upper end surface of the gear housing 6 to which the bearing 9 and the bearing 9 to which the bearing 9 is fixed can be lowered, the wall thickness in the vicinity of the upper end portion of the gear housing 6 can be reduced. Thus, the weight can be reduced, and the weight of the entire steering apparatus 1 can be reduced.

  Similarly, the required strength of the portion located above the partition wall 6a of the gear housing 6 that rotatably supports the lower main shaft 2b via the oil seal 26 and the oil seal 27 is reduced, and the partition wall 6a of the gear housing 6 is reduced. It is possible to reduce the weight by reducing the thickness of the portion located on the upper side, thereby reducing the weight of the entire steering device 1.

  The piston shaft 7 is subjected to a large axial driving force obtained by synthesizing the axial driving force by hydraulic pressure and the axial driving force by electric force, but contacts the outer peripheral surfaces of the sector shaft 8 and the piston portion 7c. The inner peripheral surface of the gear housing 6, the partition wall 6 b and the oil seal 28 of the gear housing 6, and a plurality of support points dispersed in the axial direction of the second ball nut 31 a of the motor shaft 31 of the motor 30 are firmly restrained in the radial direction. Therefore, the occurrence of displacement in the twisting direction can be suppressed as much as possible.

  This ensures that the displacement of the inner peripheral surface of the bottomed cylindrical portion 7a of the piston shaft 7 with respect to the axial direction is suppressed as much as possible, and the inner peripheral surface of the bottomed cylindrical portion 7a is lower. Since the outer peripheral surface of the main shaft 2b is firmly supported, the displacement of the lower main shaft 2b in the twisting direction can be suppressed as much as possible.

  Furthermore, when generating the assist force by the driving force of the motor 30, a gear mechanism combining a plurality of gears is eliminated, and a configuration in which the motor is disposed at a position offset from the central axis of the main shaft 2 may be eliminated. Therefore, it is possible to reduce the size of the steering device 1, particularly in the radial direction, and increase the degree of freedom in the vehicle body outfitting. In addition, since the second ball nut mechanism 29 is used in place of the gear mechanism, it is possible to increase the output of electric assist force.

  Further, in this embodiment, the steering device 1 is a recirculating ball type, and has an irreversible characteristic capable of suppressing transmission of input from the road surface via the wheel, knuckle arm, tie rod, pitman arm, and sector shaft 8 as much as possible. Therefore, the reaction force acting on the steering wheel by the impact input from the road surface, that is, the kickback can be made as small as possible. Further, the reduction ratio can be made larger than that of the rack and pinion type. That is, the steering device 1 of the present embodiment is particularly useful when applied to a vehicle having a high frequency of traveling on a rough road or a large vehicle such as a truck or a bus having a large load.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions are made to the above-described embodiments without departing from the scope of the present invention. be able to.

  For example, in this embodiment, the hydraulic valve unit 3 is a rotary valve type, but may be replaced with a spool valve type or a flapper valve type. Or you may comprise by the combination of the solenoid valve or switching valve controlled by EPSECU.

  Further, as shown in FIG. 3, the drive unit 4 is positioned below the hydraulic cylinder unit 5, the axial dimension of the bottomed cylindrical part 7a of the piston shaft 7 is shortened, and the upper end of the bottomed cylindrical part 7a is reduced. It is good also as providing the tooth surface 7e in the vicinity, providing the protrusion part 7g below the bottomed cylindrical shape part 7a, and providing the 2nd worm shaft 7f near the lower end of the protrusion part 7g. Here, the drive unit 4 is an external type, and the gear housing 6 that encloses the drive unit 4 is a separate gear housing part 6c.

  According to the form shown in FIG. 3, the axial dimension of the lower main shaft 2 b can be shortened to reduce the weight of the steering device 1. In addition, the axial dimension of the bottomed cylindrical portion 7 a of the piston shaft 7 is shortened to simplify the structure of the piston shaft 7, and the first ball nut mechanism 29 can be configured with the bottomed cylindrical portion 7 a. The piston shaft 7 can be manufactured more easily by setting the position constituting the first ball nut 7b in the space on the inner peripheral side closer to the opening of the bottomed cylindrical portion 7a.

  In addition, since both the piston portion 7c and the bottomed cylindrical portion 7a of the piston shaft 7 can be accommodated in the liquid chamber, in particular, the upper hydraulic pressure receiving surface includes the upper end portion of the bottomed cylindrical shape portion 7a. The difference in the area between the upper and lower hydraulic pressure receiving surfaces can be further reduced.

  In the form shown in FIG. 3, the hydraulic system including the hydraulic valve unit 3 and the hydraulic cylinder unit 5 is centrally arranged at the upper part of the steering device 1, and the electrically driven drive unit 4 is arranged at the lower part. The system and the electric system can be more clearly separated and arranged. Thereby, for example, when a failure occurs in only one of the hydraulic system and the electric system, replacement of parts can be made easier. Furthermore, the pipes constituting the oil passage 22 and the oil passage 23 of the hydraulic system can be further shortened, and the oil passages 22 and 23 can be built in the gear housing 6.

  The configuration shown in FIGS. 1 and 3 shows the constraints on the vehicle body structure regarding the installation positions of the pitman arm and the sector shaft 8, the installation conditions of the piping constituting the oil passage, the manufacturing cost, and the frequency of parts replacement. A convenient form can be appropriately selected and used in accordance with vehicle tests or actual data.

  The present invention relates to a steering device applied to an automobile, and in particular, in a steering device in which an electric steering device and a hydraulic steering device are combined, to increase the output of electric steering force without causing an increase in size. Therefore, it can be applied to various vehicles such as passenger cars, trucks and buses.

1 Steering device 2 Main shaft 2a Upper main shaft (first shaft)
2b Lower main shaft (second shaft)
2c 1st worm shaft 3 Hydraulic valve part (hydraulic control means)
4 Drive unit 5 Hydraulic cylinder unit 6 Gear housing (housing)
6a Bulkhead 6b Bulkhead 6c Gear housing part 7 Piston shaft (mover)
7a Bottomed cylindrical part 7b First ball nut 7c Piston part (hydraulic receiving surface)
7d Oil passage 7e Tooth surface 7f Second worm shaft 7g Protruding portion 8 Sector shaft 8a Tooth surface 9 Bearing 10 Torsion bar (elastic body)
11 Press-fit pin 12 Valve shaft 13 O-ring 14 Oil seal 15 Press-fit pin 16 Valve body 17 Press-fit pin 18 Hydraulic port 19 Hydraulic port 20 Turn port 21 Turn port 22 Oil path 23 Oil path 24 Oil seal 25 Seal retaining ring 26 Oil seal 27 Oil seal 28 Oil seal 29 First ball nut mechanism (first conversion means)
30 Motor (electric means)
31 Motor shaft 31a Second ball nut 32 Second ball nut mechanism (second conversion means)
33 Torque sensor 34 Torque sensor

Claims (1)

  A first shaft coupled to the steering wheel; a second shaft coupled to the first shaft via an elastic body; and a hydraulic pressure receiving surface extending in the axial direction of the second shaft on both sides of the axial direction A first conversion means for converting the rotational movement transmitted from the first axis to the second axis into the axial movement of the mover, and a relative rotation of the first axis with respect to the second axis. Hydraulic control means for making one of the hydraulic pressure receiving surfaces on both sides in the axial direction higher in pressure than the other hydraulic pressure, and a hollow cylindrical rotor disposed on the outer peripheral side of the mover. And a second converting means for converting the rotational motion of the rotor into the axial motion of the mover.

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