JPH04260867A - Rear wheel steering device for four-wheel steering vehicle - Google Patents

Abstract

PURPOSE:To secure the assembling-time neutral position relation, to a control valve, of cable take-up mechanism for performing the feedback of the movement of rear wheel side steering link mechanism so as to heighten the mounting performance to a vehicle. CONSTITUTION:A take-up pulley 27 forming the feedback cable take-up mechanism 28 built in a housing body together with a rear wheel steering control valve 20 is assembled in such a way as to have the neutral position relation with the valve 20. The take-up pulley 27 is then temporarily fixed by a temporarily fixing pin 48 inserted from outside a body while keeping the relative position relation in its rotating direction. In this state, the take-up pulley 27 is built in a vehicle and connected to rear wheel side steering link mechanism by a feedback cable 4, and the temporarily fixing pin 48 is removed to connect the take-up pulley 27 onto the rear wheel side.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is used to steer a rear wheel in the opposite direction in conjunction with the front wheels by steering operation, thereby achieving a small turning radius at low speeds. Concerning improvements to rudder devices.

0002

[Prior Art] In recent years, by steering the rear wheels in the opposite direction or the same direction according to the amount of steering (steering amount) of the front wheels, it has been possible to improve the ability to turn around at low speeds, and to improve the ability to turn around when driving at medium or high speeds. Four-wheel steering vehicles that can improve driving stability are attracting attention. For example, when driving at low speeds, the front wheels are steered with a large steering angle. At this time, by setting the steering directions of the front and rear wheels in opposite phases (reverse direction steering), the vehicle's turning radius is minimized and the turning (small turning) performance is improved. It is particularly suitable for application to long vehicles such as trucks. Rear wheel steering devices for this type of four-wheel steering vehicle are disclosed, for example, in Japanese Patent Laid-Open Nos. 59-128054 and 59-128054;
Publication No. 143769, Publication of Utility Model Application No. 61-53271,
Devices having various structures have been proposed in the past, including the hydraulic device shown in Japanese Patent Application Laid-Open No. 61-67665. In particular, with hydraulic devices, the rear wheels are steered in the desired direction by selectively supplying hydraulic pressure controlled to a predetermined pressure by a servo valve, etc. to the left and right chambers of the hydraulic cylinder for steering the rear wheels. It has the advantage of having a greater degree of freedom in terms of movement and structure than a mechanical device that mechanically connects the front and rear wheels with a connecting shaft, etc. It was something.

0003

[Problems to be Solved by the Invention] However, the above-mentioned conventional device still has advantages and disadvantages in terms of structure and operational performance, and there is still room for improvement in putting it into practical use. For example, this type of rear wheel steering device requires the minimum number of component parts, unitizes each part to improve workability and assembly, and reduces manufacturing costs, as well as hydraulic piping, electrical wiring, etc. It is desired that these devices be able to be arranged efficiently and in line, be able to perform various drive controls simply and appropriately, and have sufficient measures against failures. Among these demands, what is needed is a control system structure for steering the rear wheels in a desired state in conjunction with the steering operation of the front wheels accompanying a steering operation. In particular, when the rear wheels are steered in conjunction with the steering action of the front wheels, the displacement transmission control means for rear wheel steering transmits the required play stroke to the rear wheels according to the amount of steering displacement on the front wheels. In addition to controlling the operation of the rear wheel steering control valve based on the rotational displacement of It is desirable to efficiently combine and arrange them in an appropriate manner, taking into consideration the relationships among them. In particular, the idea is to configure the cable winding mechanism for connecting such a feedback system to the control valve side as a unit together with the control valve, thereby simplifying the configuration of each part and improving the ease of incorporation into the vehicle. However, in this case, the structure of the connecting part of the feedback cable for connecting the rear wheel side steering link mechanism side and the control valve side becomes a problem after installation into the vehicle. In other words, the feedback cable winding mechanism needs to be positioned in the rotational direction to match the neutral position of the control valve, but the connection with the rear wheel steering link mechanism by the feedback cable is difficult. Since this is performed after the device is installed in the vehicle, it has generally been considered that the above-mentioned positioning work of the cable winding mechanism with respect to the valve side is also performed after the device is installed in the vehicle. However, when a rear wheel steering system is installed in a vehicle, it is troublesome and complicated to position the relative connection parts of each mechanical part, and the control valve is not designed to transmit steering force from the front wheels. In this system, the feedback cable is mechanically connected to the rear wheel side steering link mechanism, and it is necessary to secure a neutral position on this rear wheel side, which requires delicate positioning adjustment work. In particular, if the above-mentioned cable winding mechanism is assembled into a housing body etc. together with a control valve, even if these are positioned in the required state and assembled, when assembled into a vehicle, the body will be reattached. It is necessary to disassemble and adjust the positioning, and this is noticeable from the standpoint of adjusting the positioning of the control valve part at the neutral position, which requires delicate positioning adjustments, and is problematic from the standpoint of installation of the device on the vehicle. It is desirable to take some measures to eliminate these problems.

0004

[Means for Solving the Problems] In order to meet such demands, a rear wheel steering device for a four-wheel steering vehicle according to the present invention provides a power cylinder for steering the rear wheels in conjunction with a steering operation on the front wheel side. A rear wheel steering control valve that switches and controls the hydraulic passage of the rear wheel side steering link mechanism to control the steering of the rear wheel side steering link mechanism, and a rear wheel steering control valve that is pivotally supported on a feedback shaft disposed coaxially with the output shaft of the control valve. A cable winding mechanism consisting of a feedback cable winding pulley that feeds back the movement of the wheel side steering link mechanism and a return spring that biases this winding pulley in the cable winding direction, these control valves, and the cable winding mechanism. It is equipped with a housing body that accommodates and arranges the mechanism, and the take-up pulley is inserted from the outside of the housing body while maintaining the relative positional relationship in the rotational direction with the control valve side during assembly. A temporary fixing pin is provided that is temporarily locked and removed when installed in a vehicle.

[0005]

[Operation] According to the present invention, the winding pulley constituting the cable winding mechanism to which the feedback cable from the rear wheel side steering link mechanism is connected is built into the housing body, and is also built into this body. In this state, the take-up pulley is temporarily locked in its rotational direction with a temporary fixing pin from outside the body, and the take-up pulley is assembled into the vehicle. After connecting the feedback cable from the rear wheel side to the side, the rear wheel steering system can be connected to the control valve side by removing the temporary fixing pin.

[0006]

[Embodiment] FIGS. 1 to 10 show an embodiment of a rear wheel steering device for a four-wheel steering vehicle according to the present invention. In this embodiment, as shown in FIG. The mechanism (only the rear wheel side is designated by reference numeral 1 and the front wheel side is not shown) is independently driven by hydraulic power cylinders 2 and 3, and only the steering displacement information on the front wheel side is used as a hydraulic signal for the rear wheel side. In addition to transmitting the information to the wheel steering drive system, the rear wheel side steering displacement (
The control system (rear wheel steering control valve 11 to be described later) is controlled by the feedback cable 4 (rod movement amount of the power cylinder 3).
) A rear wheel steering device 10 configured to include a signal system 5 that provides feedback to the vehicle will be described. Here, 6,
7 is an oil pump for supplying pressure oil to the front and rear power cylinders 2 and 3, 8 is an oil tank, and the pressure oil from the front wheel pump 6 is guided to the front power cylinder 2 through a hydraulic pipe 6a. A well-known front wheel side power steering device is configured in which the oil is returned to the oil tank 8 through the return pipe 6b. Also,
Reference numeral 9 indicates an on-vehicle battery, and in FIG. 9, hydraulic piping is shown as a double line, and electrical wiring is shown as a single solid line. Although the oil pumps 6 and 7 are dual pumps driven simultaneously by an automobile engine (not shown), the present invention is not limited to this, and the oil pumps 6 and 7 may be configured with independent hydraulic systems for the front and rear wheels.

Further, the device 10 of this embodiment uses the required play in the rear wheel steering control valve mechanism 11 for controlling the steering of the rear wheels by using the steering displacement information on the front wheels accompanying the steering operation. (
As is clear from the characteristic curve shown in Fig. 10, the displacement transmission control means for rear wheel steering selectively transmits transmission with a dead zone), and does not transmit rotation while the steering wheel is being steered within a certain angle from the neutral position. Instead, a displacement transmission control mechanism 12 using a dead band link mechanism or the like configured to transmit rotational displacement with predetermined characteristics when the vehicle is further steered is used. Note that this displacement transmission control mechanism 12
is equipped with steering detection switches SW1 and SW2 for detecting the steering direction and steering condition of the steering wheel, and the steering direction display lamps 13a and 13b are turned on by turning on and off these switches SW1 and SW2. The steering direction for the front and rear wheels can be displayed from the driver's seat. Here, these steering detection switches SW1
, SW2 are configured to turn off when the steering angle is within about 300 degrees from the straight-ahead state (neutral position), and turn on when the steering wheel is steered beyond that point. In addition, in the electrical circuit from the battery 9 shown in FIG. 9 to the rear wheel steering device 10 that characterizes the present invention, reference numeral 14 indicates a manual forced operation of the rear wheel steering device 10 when the driver senses an abnormality while driving. 15 is a detection switch as a cable/return spring failure detection means to be described later; 16 is a power cylinder 3 side constituting the steering link mechanism 1 for steering the rear wheels; A neutral position detection switch 17 is attached to and detects the neutral position of the rear wheels as an off signal, and 17 is a normally closed type relay switch for controlling current flowing to a negative actuation type clutch mechanism, which will be described later. Further, reference numeral 18 denotes a normally open type bypass valve that opens and closes a bypass path between a hydraulic pipe 7a from the rear wheel steering oil pump 7 and a return pipe 7b from a control valve, which will be described later. 9 turns on the solenoid, which closes the bypass path, and the emergency switch 14, cable/return spring failure detection switch 15, etc. are turned off and are no longer energized, opening the bypass path. No wheel steering 2
It is configured to be in the WS state.

Now, in the device of the present invention, the rear wheel steering control valve mechanism 11 for controlling the steering of the rear wheels by the rotational displacement transmitted from the above-mentioned displacement transmission control means is shown in FIGS. As is clear from FIG. 7 etc., switching control of the hydraulic passage from the oil pump 7, which is the rear wheel side hydraulic pressure source, is performed according to the displacement amount obtained by the displacement transmission control mechanism 12, and the power steering for steering the rear wheels is performed. 3, and a rotary rear wheel steering control valve 20 for operating the rear wheel steering control valve 20. A feedback cable 4 forming a feedback signal system 5 that feeds back the movement of the rear wheel side steering link mechanism 1
a cable winding mechanism 28 consisting of a winding pulley 27 and a return spring 29 that biases the winding pulley 27 in the winding direction of the cable 4;
The housing body (31A, 31B; 32) is configured to accommodate the rear wheel steering control valve 20 and the rear wheel steering control valve 20 therein. In this embodiment, the control valve 20 and the cable winding mechanism 28 described above are installed between these mechanical parts within the body incorporating the control valve 20 and the cable winding mechanism 28.
It is interposed between the output shaft 22 and the feedback shaft 23 on the 0 side, and by connecting these two shafts 22 and 23 so that they can be rotated relative to each other, it absorbs the steering delay on the rear wheel side with respect to the steering operation. a delay absorption spring mechanism 25 for
This delay absorbing spring mechanism 25 and the control valve 20
This figure shows a case in which a negative actuation type clutch mechanism 26 is interposed between the two and selectively connects the two. Further, a part of the cable winding mechanism 28 is activated in conjunction with the movement of the cable winding mechanism 28 that occurs when either the return spring 29 or the cable 4 fails, and generates a failure signal. A sending cable/return spring failure detection means 30 is attached. According to the configuration of this embodiment, the rear wheel steering control valve 20, the negative actuation type clutch mechanism 26, the delay absorption spring mechanism 25,
By arranging the cable winding mechanism 28 and the cable/return spring failure detection means 30 in parallel on the same axis as the input and output shafts 21 and 22 of the control valve 20 and the feedback shaft 23 and forming a unit, the entire system can be improved. This simplifies the configuration and ensures displacement transmission, and also improves the ease of assembling the mechanical unit and incorporating it into a vehicle.

The schematic structure of the unitized rear wheel steering control valve mechanism section 11 constituting the rear wheel steering device 10 illustrated in this embodiment will be briefly explained using FIGS. 1 to 4 and the like. Then, 31A and 31B are housing bodies that constitute the valve mechanism section 11 with the cylindrical member 32 interposed therebetween, and 33 is the valve 20 that is screwed and attached to the end of the housing body 31A. A rotor 34 and a sleeve 35 (formed in series on the output shaft 22) are installed inside the pump port 3.
6. A valve body in which a hydraulic passage leading to a tank port 37 etc. is formed, and a part of the above-mentioned hydraulic passage is an output port 38 formed on the housing body 31A side.
, 39. In addition, in the figure, P indicates the pump 7, T indicates the tank 8, and C1.
, C2 are the left and right chambers of the power cylinder 3 on the rear wheel side. Further, in the figure, 40 is a torsion bar that connects the input and output shafts 21 and 22 such that they can rotate relative to each other. The control valve 20 is switched to a desired state by the rotational displacement from the displacement transmission control mechanism 12 in response to the steering operation, thereby requiring rear wheel steering control by the rear wheel steering power cylinder 3. It is configured so that it can be performed under the following conditions. Here, as components including the input and output shafts 21, 22, the rotor 34, the sleeve 35, etc. that constitute the control valve 20 described above, a rotary flow path for a front wheel side power steering device that has been generally used in the past is used. It is advantageous from a practical point of view to repurpose parts used for switching valves.

In the control valve mechanism 11 having the above-described configuration, the feedback shaft 23 is provided within the housing body 31B as described above, as is clear from FIGS. 4, 7, and 8. A winding pulley 27 constituting a cable winding mechanism 28 that characterizes the present invention, to which one end of a feedback cable 4 for feeding back the steering state of the rear wheels is connected and the cable 4 can be wound. is rotatably supported, and a feedback transmission plate 41 that can be connected to the winding pulley 27 in the rotational direction is fixed on the feedback shaft 23 adjacent to the pulley 27 . The transmission plate 41 is urged in the cable winding direction with respect to the pulley 27 by the return spring 29. As shown in FIG. 7, this transmission plate 41 has arc-shaped notches 41a, 41a formed at two locations in the circumferential direction.
By engaging the engaging pins 42, 42 protruding in the axial direction from the winding pulley 27 into the inside a, rotation transmission in the left and right direction between the transmission plate 41 and the pulley 27 is performed at a predetermined angle. It is configured so that it can be performed with a range of play,
The winding pulley 27 is also connected to the winding pulley 27 via a transmission plate 41 biased by a return spring 29 on the feedback shaft 23.
In addition, it is configured to apply a biasing force in a direction that always applies tension to the cable 4, thereby eliminating slack in the cable 4. Here, the winding pulley 27 and the transmission plate 41 are arranged so that the engagement pins 42 and 42 are normally disconnected by a cable/return spring failure detection promotion spring 43 that is provided to extend inside the winding pulley 27 and the transmission plate 41. It is configured to operate integrally by engaging with the ends of the notches 41a and 41b in the rotational direction. and cable 4 or return spring 29
Engagement means for generating relative rotational displacement between the pulley 28 and the plate 41 by utilizing the biasing force of the spring 43 and transmitting rotation between these members when the pulley 28 and the plate 41 fail. The engaging pin 42 is adapted to move within the notch 41a in the direction opposite to the winding direction of the cable 4. Note that this spring 43 is configured to have a weaker urging force than the return spring 29. Further, as is clear from FIG. 8, the winding pulley 27 described above is a cylindrical body 4 having a flange portion 44 on the transmission plate 41 side.
5 and a flange 46 screwed and fixed to the other end of this cylindrical body 45 with a plurality of setscrews 47.
The locking rod portion 4a at the tip of the cable 4 is inserted into the circular arc groove 45a recessed in a part of the outer periphery of the cable 4 and the circular hole 44a continuously drilled in the flange portion 44 to lock the cable. By screwing the flange 46 in this state,
One end of the cable 4 is fixed to the pulley 27 side.

Now, according to the present invention, in the above-described configuration, together with the control valve 20, the housing body 31A,
31B; Feedback cable 4 incorporated in 32
As is clear from FIGS. 1 and 7, when the control valve mechanism section 11 is assembled, the winding pulley 27 is connected to the control valve 20 side while maintaining the relative positional relationship in the rotational direction, and the housing body 31B is characterized in that it is provided with a temporary fixing pin 48 that is temporarily locked by being inserted from the outside and removed when mounted on a vehicle. According to such a configuration, the winding pulley 27 constituting the cable winding mechanism 28 to which the feedback cable 4 from the rear wheel side steering link mechanism 1 side is connected is incorporated into the housing body 31B, and A neutral position is determined with respect to the control valve 20 that is also incorporated into the body 31B, and in this state, the rotational direction of the take-up pulley 27 is temporarily locked using a temporary fixing pin 48 inserted from outside the body 31B. After the feedback cable 4 from the rear wheel side is connected to the winding pulley 27 side in the required state, the rear wheel steering system is controlled by the control valve 20 by removing the temporary fixing pin 48. This can be connected to the rear wheel side steering link mechanism 1.
It is possible to appropriately and reliably ensure the neutral positional relationship of the cable winding mechanism 28 that feeds back the movement of the cable winding mechanism 28 with respect to the control valve 20 during assembly, thereby improving the ease of mounting on the vehicle. In particular, control valve 2, which requires troublesome adjustment work.
0 can be reliably adjusted only by adjustment during assembly, and can be mounted on the vehicle as is.

Further, on the side of the cable winding mechanism section 28 having the above-described structure, there is a movable member 50 which is held on the inner side of the pulley 27 so as to be movable in the axial direction. A contact 51 is provided which is rotatably connected and whose other end selectively contacts the cable/return spring failure detection switch 15.
A return spring failure detection means 30 is configured. here,
In the figure, 52 is provided protruding from the movable member 50 toward the pulley 27, passes through the cylindrical body 45 of the winding pulley 27, and is normally in contact with the end surface of the transmission plate 41 as shown in FIG. This is a failure detection pin that locks the movement in the direction, and in this state, the switch 15 is kept in the ON state, and if a failure occurs in the cable 4 or the return spring 29, etc., the pulley 27 and movable with respect to the transmission plate 41. Due to the relative rotation of the member 50, the contact position of the failure detection pin 52 on the end face of the transmission plate 41 changes, and the pin 52 has a larger diameter than the pin 52 drilled at that displaced position. engagement holes 53, 53
When the pin 52 is engaged with the movable member 5
0 Further, by moving the contactor 51 in the axial direction, the switch 15 is turned off, and by detecting failure of the cable and return spring, the bypass valve provided in the middle of the hydraulic circuit for rear wheel steering control is activated. 18 is configured to be opened. That is, such a cable 4,
This is because, in the event of a failure of the feedback system in which the return spring 29 fails, the rear wheels are brought into a non-steering state, and only the front wheels are put into the 2WS state. Note that the spring force of the return spring 29 mentioned above is
The tension is set equal to the tension in the cable 4, and the spring force of the failure detection promotion spring 43 is set smaller than the spring force of the return spring 29. Also, in Figure 4 etc., 54
closes the open end of the housing body 31B and closes the switch 1
A closing plate to which 5 etc. are assembled, 55 is a contact 51
This is a spring means that biases the switch away from the switch 15. According to the cable winding mechanism 28 and the cable/return spring failure detection means 30, when the transmission plate 41 attempts to rotate counterclockwise in FIG. , 41a engages, and rotational torque in the same direction acts on the pulley 27, which applies a tensile force to the cable 4, which acts as a load on the rear wheel steering power cylinder 3 side. do. This causes a relative rotational displacement in the control valve 20 portion, causing pressure oil to flow to the power cylinder 3 side, moving the rear shaft side, and thereby also moving the cable 4 in the above-mentioned pulling direction. The plate 41 and pulley 27 also rotate counterclockwise in the figure in unison. Further, when the plate 41 tries to rotate clockwise in FIG. 7, the return spring 29 becomes a load, and the control valve 2
A relative rotational displacement occurs in the 0 portion, pressure oil is guided to the power cylinder 3, the rear shaft moves, and the cable 4 also moves to the pulley 27.
As a result, the pulley 27 and plate 41 rotate clockwise in the figure as a unit. In the cable winding mechanism section 28 in such a normal state, the pulley 27 and the plate 41 rotate together, but if a failure occurs in the cable 4 or the return spring 29, the pulley 27 and the plate 41 A relative rotational displacement will occur between them. That is, when the cable 4 fails, the tension of the cable 4 becomes 0, and the plate 41 and the pulley 27 move due to the spring force of the return spring 29, but at the same time, the pulley 27 moves against the failure detection promotion spring 43.
As a result, the engagement pin 42 is disengaged from one side edge of the notch 41a. In other words, plate 41 and pulley 2
As a result, the failure detection switch 15 is turned off, the electric circuit to the bypass valve 18 is cut off, and the rear wheel steering system becomes inoperative, resulting in the 2WS state. Further, if the return spring 29 fails, the pulley 27 will move due to the tension acting on the cable 4, but at this time, the plate 41 will normally maintain its position due to the failure detection promotion spring 43. Therefore, a relative displacement occurs between them, and this causes the switch 15 to operate in the same manner as described above, resulting in 2WS. Depending on the direction of movement of the plate 41, the control valve 20 operates and pressure oil is sent to the rear wheels to move the rear axle. At this time, the movement is fed back, and the relative displacement caused by this causes the failure state to be detected. It becomes possible to perform detection and enter the 2WS state. And like this, cable 4
By incorporating the winding mechanism 28 that performs feedback and the cable/return spring failure detection means 30 attached thereto into the unit of the control valve mechanism section 11 and configuring it integrally with the control valve 20, It is possible to assemble the feedback system in association with the control valve 20 without being affected by external influences, and
This has the advantage that the operation of the control valve 20 can be appropriately controlled. In particular, in the rear wheel steering system, the failure state of the cable 4 and the return spring 29 that feed back the rear wheel steering condition to the control valve 20 can be detected by bypassing the hydraulic circuit with the bypass valve 18 and This is necessary to bring the wheels into a non-steering state and to bring only the front wheels into the 2WS state.

In this embodiment, the control valve mechanism 11 has a delay absorbing spring mechanism 25 and a negative actuating spring mechanism 25 between the feedback shaft 23 to which the feedback system is connected and the output shaft 22 on the control valve 20 side. A type clutch mechanism 26 is interposed therebetween. To explain this simply, as is clear from FIGS. 1 and 3, the delay absorption spring mechanism 25 includes a flange-like member 60 provided on the feedback shaft 23, and a flange-like member 60 that is rotatable on the feedback shaft 23 and the output shaft 22. A coil spring 63 connects a flange-like member 62 provided on the sleeve shaft 61 so as to be able to rotate relative to the flange-like member 62 when a predetermined load or more is applied in the circumferential direction. We are prepared. The coil spring 63 is loosely fitted to the outer circumferential portion of the sleeve shaft 61, and its both ends are locked to the flanged members 60 and 62 on both sides. When a displacement exceeding the setting occurs due to a delay in steering on the rear wheel side during sudden steering, etc., the relative rotation between the feedback shaft 23 and the sleeve shaft 61 is displacement is possible, so that this sleeve shaft 61
It functions like a torsion bar with a large preset angle that can prevent slipping in the negative actuation type clutch mechanism 26 for selectively connecting the output shaft 22 to the output shaft 22 on the control valve 20 side. In this delay absorbing spring mechanism 25, both ends of the coil spring 63 extend in the radial direction substantially in parallel, as is clear from FIGS. 3 and 5, and the extending portions 63a and 63b , a locking pin 64 protruding in parallel from the flange-like members 60 and 62;
, 65 are arranged so as to sandwich them from both sides in the circumferential direction, thereby elastically integrating both the flange-like members 60 and 62. In this embodiment, in order to ensure stable operating characteristics of the spring force and wear due to point contact and sliding action at the contact portions of the spring extension portions 63a and 63b with the locking pins 64 and 65, As is clear from FIGS. 5 and 6, there is a concave groove 67b that holds the locking pins 64, 65.
, 67c, and a through hole 67a into which the spring extension portions 63a, 63b are fitted,
This makes it possible to improve wear resistance, etc. Further, the negative actuation type clutch mechanism 26 is provided to be slidable only in the axial direction on the output shaft 22 so as to be selectively attracted to the excitation coil 70 provided in a part of the housing body 31A. A toothed portion 71a integrally provided on a part of the armature member 71 meshes with a toothed portion 61a on the sleeve shaft 61 side, thereby allowing the output shaft 22 and the sleeve shaft 61 to be connected to each other. Feedback axis 2
3 are connected. That is, this negative actuation type clutch mechanism 26 is used to eliminate changes over time such as elongation of the cable 4, and to eliminate the deviation that occurs between the neutral position state of the control valve 20 and the neutral position state on the rear wheel side. When the steering wheel is in the neutral state or the front wheel is in the 2WS state, this clutch mechanism 26 is energized and turned on to disengage the clutch, and in the 4WS state, the clutch mechanism 26 is turned off. This makes it a clutch joint. Here, this clutch mechanism 26 is designed to prevent elongation of the cable 4 over time, control valve 20,
This is for correcting a neutral position shift between the control valve 20 and the power cylinder 3 due to a change in the distance between the rear wheel steering power cylinders 3, etc. By the way, in the present invention, a negative-actuation type clutch mechanism 26 is used, but in a general positive-action type, when the ignition key switch is turned off while the rear wheels are being steered, the clutch mechanism 26 is turned off. As a result, the phase relationship between the control valve 20 and the power cylinder 3 is shifted by the torsion angle of the torsion bar.It is desirable to use a negative actuation type clutch coupling even when the ignition is off. It is something.

In the above-mentioned rear wheel steering device 10, as is clear from FIG. 9, the steering link mechanism 1 for rear wheel steering has a control valve 20 connected to a power cylinder 3 for rear wheel steering to the left and right chambers. A hydraulic failure check valve mechanism 81 is installed in the middle of the hydraulic pipes 80a and 80b to resolve problems caused by oil pressure failure, and the link mechanism 1 is always locked in a neutral position to keep the rear wheels from rotating. A neutral position locking mechanism 82 by the left and right deadlock point mechanisms for maintaining the rudder state, and a lock release for releasing the deadlock of the locking mechanisms 82, 82 using the pressure oil in the hydraulic pipes 80a, 80b. A cylinder mechanism (not shown), a centering spring mechanism 83 for returning the rear wheels to the neutral position, a neutral position detection switch 16 for detecting whether the rear wheels are in the neutral position, etc. are attached. However, detailed explanation thereof will be omitted.

In the rear wheel steering device 10 having the above configuration, rear wheel steering control is performed as follows. That is, when the engine is started, pressure oil is supplied from the pumps 6 and 7 to the front wheel and rear wheel steering systems, and during normal driving, the front wheel control valve, the rear wheel control valve 20, or the bypass valve 1 is supplied.
A circulation path returning to the tank 8 via the tank 8 is constructed. In this state, when the steering wheel is steered in either direction, the front wheel side steering link mechanism uses the flow path switching function by the front wheel side control valve to transfer pressurized oil to the front wheel side power cylinder 2.
is sent to one of the cylinder chambers, and the front wheels are steered in the desired steering direction. On the other hand, when the steering angle on the front wheel side reaches a certain angle or more, the steering detection switch SW1, S
Either W2 turns on, which causes bypass valve 1
8 is turned on, a flow path for steering the rear wheels is formed, and the power supply to the negative actuation type clutch 26 is stopped within the control valve mechanism 11, and the clutch is engaged, so that the 4WS is ready. Become. In this state, the steering angle on the front wheel side becomes greater than that, and the rotational displacement from the displacement transmission control mechanism 12 for rear wheel steering causes the rear wheel side control valve 20 to move between its input and output shafts.
The rotor 34 due to the relative rotational displacement that occurs between 1 and 22.
By switching the flow paths between the sleeve 35 and the sleeve 35, pressure oil is supplied to either cylinder chamber of the rear wheel steering power cylinder 3 on the steering link mechanism 1 side on the rear wheel side. At this time, in the cable winding mechanism 28, the cable 4 side or the return spring 29 side becomes a load, and as a result, a load is applied between the input and output shafts 21 and 22 of the control valve 20 via the feedback shaft 23, sleeve shaft 61, and armature member 71. Needless to say, relative rotational displacement is caused by twisting the torsion bar 40. At the same time, the lock release cylinder mechanism is operated by the supplied pressure oil to release the deadlock point mechanism of the rear wheel neutral position locking mechanism 82, thereby releasing the respective locked states. After this lock is released, the power cylinder 3 operates to operate the rear wheel side steering link mechanism 1 to control steering of the rear wheels in a desired direction. This rear wheel steering state is fed back from the above-mentioned winding mechanism 28 to the control valve 20 side via the cable 4. on the other hand,
When the steering wheel is returned to a predetermined angle from the above-mentioned steering state, this movement is transmitted to the control valve 20, and the rear wheel steering is performed based on the flow of pressure oil, which is controlled in relation to the feedback of the rear wheel steering state. The link device 1 is controlled to be steered in the return direction. When the rear wheels are in the neutral position, the rear wheels are locked by the neutral position locking mechanism 82 formed by the deadlock point mechanism, and the neutral position detection switch 16 is turned off. Furthermore, when the steering wheel is returned to the neutral position, the steering detection switch is turned off, power supply to the bypass valve 18 is stopped, and power is supplied to the negative actuation type clutch 26, resulting in a clutch disengaged state. The condition will be as follows.

It should be noted that the present invention is not limited to the structure of the above-described embodiment, and the shape, structure, etc. of each part of the rear wheel steering device 10 may be modified or changed as appropriate, and various modifications may be considered. For example, in the above-mentioned embodiment, although the specific disclosure is omitted as the displacement transmission control mechanism 12 for rear wheel steering, the structure is such that a steering signal to the rear wheels can be obtained in conjunction with the steering operation of the front wheels. Various modifications may be considered.

[0017]

As explained above, according to the rear wheel steering device for a four-wheel steering vehicle according to the present invention, the hydraulic passage to the power cylinder for rear wheel steering is switched in conjunction with the steering operation on the front wheel side. A control valve for rear wheel steering to be controlled, and a feedback cable that is supported on a feedback shaft coaxially arranged with the output shaft of the control valve and that feeds back the movement of the rear wheel steering link mechanism. The cable winding mechanism includes a cable winding mechanism consisting of a pulley and a return spring that biases the winding pulley in the cable winding direction, and a housing body that houses and arranges these control valves and the cable winding mechanism. A temporary fixing pin that is inserted from the outside of the housing body to temporarily lock the take-up pulley while maintaining the relative positional relationship in the rotational direction with the control valve side during assembly, and is removed when installed on the vehicle. Despite its simple configuration, the control valve mechanism, which integrates the cable winding mechanism that feeds back the movement of the rear wheel steering link mechanism with the control valve, can be assembled easily. After the feedback cable from the rear wheel side is connected to the winding pulley side, the temporary fixing pin is removed to complete the installation into the vehicle.
Excellent in terms of wearability. In particular, according to the present invention, control valves for which delicate adjustment and reliable positioning are desired can be maintained in the adjusted state at the time of assembly without changing them.
It has the advantage of being able to be mounted on a vehicle.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the overall configuration of a control valve mechanism for rear wheel steering, which is a main part of a rear wheel steering device for a four-wheel steered vehicle according to the present invention.

FIG. 2 is an enlarged cross-sectional view of the main part of FIG. 1;

FIG. 3 is an enlarged cross-sectional view of the main part of FIG. 1;

FIG. 4 is an enlarged cross-sectional view of a main part of FIG. 1 showing a feature of the present invention.

FIG. 5 is a detailed view of the coil spring portion of the delay absorbing spring mechanism.

FIG. 6 is a detailed view of a receiving member attached to the spring end.

FIG. 7 is a detailed view of the feedback cable winding mechanism that characterizes the invention.

FIG. 8 is a schematic exploded perspective view for explaining the connection state between the cable winding pulley and the cable end.

FIG. 9 is a diagram showing a schematic configuration of the entire rear wheel steering device.

FIG. 10 is a characteristic diagram showing the input angle on the steering handle side and the control valve operating angle.

[Explanation of symbols]

1 Rear wheel steering link mechanism 2 Front wheel steering power cylinder 3 Rear wheel steering power cylinder 4 Feedback cable 5 Feedback signal system 6 Front wheel oil pump 7 Rear wheel oil pump 8 Oil tank 10 Rear wheel steering device 11 Rear wheel steering Rudder control valve mechanism section 12
Displacement transmission control mechanism for rear wheel steering 15 Cable/return spring failure detection switch 16 Neutral position detection switch 18 Bypass valve 20 Control valve for rear wheel steering 21 Input shaft 22 Output shaft 23 Feedback shaft 25 Delay absorption spring mechanism 26 Negative actuation type Clutch mechanism 27 Take-up pulley 28 Cable take-up mechanism 29 Return spring 30 Cable/return spring failure detection means 31A
Housing body 31B Housing body 32 Cylindrical member 41 Transmission plate 48 Temporary fixing pin

Claims (1)

[Claims] Claim 1: A rotary system that controls switching of a hydraulic passage from a rear wheel hydraulic power source to a power cylinder for rear wheel steering in conjunction with steering operation on the front wheel side, and controls steering of a rear wheel steering link mechanism. A rear wheel steering control valve and a winding of a feedback cable that is supported on a feedback shaft coaxially disposed on the output shaft of the rear wheel steering control valve and feeds back the movement of the rear wheel side steering link mechanism. A cable winding mechanism consisting of a take-up pulley and a return spring that biases the take-up pulley in the cable winding direction, and a housing body that accommodates and arranges these control valves and the cable winding mechanism. When assembled, the take-up pulley is connected to the control valve side while maintaining the relative positional relationship in the rotational direction, and is inserted from the outside of the housing body and temporarily locked, and removed when installed on the vehicle. A rear wheel steering device for a four-wheel steering vehicle, characterized in that a temporary fixing pin is provided.