JPH035281A - Four-wheel steering device - Google Patents

Abstract

PURPOSE:To always obtain optimum rear wheel steering characteristic with simple construction by providing a steering characteristic adding mechanism consisting of V-shaped guide grooves and a pair of engaging elements to engage with them, between an input shaft and a followingly rotating member continuously engaged with this in the housing of a rear wheel steering device. CONSTITUTION:A followingly rotating member 33 having an eccentric axis of rotation O2 against the axis of rotation O1 of an input shaft 31 and connected to an output shaft 51 is provided in the housing 21 of a rear wheel steering device 20, and V-shaped a pair of guide grooves 37 which are respectively extended in the radial direction and the outer ends 37a are opened free from the outer circumferential face of the followingly rotating member 33, are formed on the face of the member 33 opposing to the input shaft 31. A pair of engaging elements 34 engaging with the respective guide grooves 37 are projectingly provided on the end face of the input shaft 31 to constitute a steering characteristic adding mechanism 30. Respective engaging elements 34 are provided so as to have same eccentricity from the rotating axis O1 mutually and alternately enter respective opposing guide grooves 37 through the opened outer end 37a, according to the rotation of the input shaft 31.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a front wheel steering device and a rear wheel steering device that are linked via a transmission device to steer the rear wheels according to the steering angle of the front wheels. This invention relates to a four-wheel steering system.

(Prior art) As this type of four-wheel steering device, for example,
No. 52,578, this technology includes a complicated coupling mechanism and drive mechanism in order to change the rear wheel steering characteristics according to the vehicle speed.

(Problems to be Solved by the Invention) For this reason, the above-mentioned conventional technology has an extremely complicated structure as a whole.6 The present invention solves such +IIjm and obtains the necessary rear wheel steering characteristics with a simple structure. The purpose is to provide a four-wheel steering device that can perform

(Means for Solving the Problems) For this purpose, the four-wheel steering device according to the present invention has a front wheel steering device 1 that steers the front wheels, as illustrated in FIGS. 1 to 4.
0 and a rear wheel steering device 20 for steering the V1 wheel, and this rear wheel steering device is connected to an input shaft 31 to which the operation of the front wheel steering device 10 is transmitted via a transmission device, and to this input shaft. In a four-wheel steering device comprising an output shaft 51 that steers the rear wheels in conjunction with the front wheels, the input shaft 31 and the output shaft 51 are each rotatable within the rear wheel side hose song 21 of the rear wheel steering device 20. and are arranged and supported in the axial direction, have a rotational axis 02 eccentric to the rotational axis #1LO1 of the input shaft 31, are provided facing the end surface of the dojin blade shaft, and are connected to the output shaft 51. Rotating member 33
and a pair of guide grooves arranged in a V-shape on the surface of the driven rotating member facing the input shaft 31, each extending in a substantially radial direction, and having outer ends 37a open from the outer peripheral surface of the driven rotating member. 37, and are provided protrudingly on the end face of the input shaft 31, and have the same eccentricity from the rotation axis o1 of the doujin blade shaft, and are inserted into the corresponding guide grooves 37 according to the rotation of the doujin pongee. It consists of a pair of engagers 34 that enter into each other from the direction of the center plane of the bevel through the open outer end 37a and are engaged with the guide groove to transmit the rotation of the dowel blade shaft to the driven rotation member 33. The present invention is characterized in that it includes a steering characteristic imparting mechanism 30.

(Function) In the front wheel steering neutral state, each engaging element 34 and the guide groove 3
7 are arranged symmetrically with respect to a plane connecting both rotational axes 01 and 02, and each engaging element 34 is engaged with the vicinity of the outer end 37a of the corresponding guide groove 37. When the input shaft 31 rotates in one arbitrary direction in this state, one of the engagers 34 enters the corresponding guide groove 37 from the outer end 37a along the center plane, engages, and rotates drivenly. Member 33
, and the other retainer 34 moves in a direction away from the corresponding guide groove 37. As a result, the angular velocity of the driven rotating member 33 is initially approximately O, but as the input shaft 31 rotates, it continuously increases. This driven rotating member 3
Since the output shaft 51 to which No. 3 is connected rotates in the same way, if the front wheels are steered from the neutral steering position, the steering angular velocity of the rear wheels is initially zero, and as the front wheel steering angle increases, it continuously increases. increase

(Effects of the Invention) As described above, according to the present invention, the steering angular velocity of the rear wheels is zero when the front wheels are near the neutral steering position, and increases continuously as the front wheel steering angle increases. Therefore, favorable rear wheel steering characteristics can be obtained in which the rear wheels are hardly steered during high speed driving when the front wheel steering angle is small, and the rear wheel steering angle increases during low speed driving when the front wheel steering angle is large. In addition, the steering characteristic imparting mechanism has a small number of parts (and each part has a relatively simple shape, so it is easy to manufacture and only requires a small increase in manufacturing cost.

(Example) The present invention will be explained below using examples shown in FIGS. 1 to 4.

As shown in the second column, in this embodiment, power steering devices are used as the front wheel and rear wheel steering devices rn10.20, respectively. A predetermined amount of working fluid sucked in from a reservoir 62 and sent out by a supply pump 60 driven by an automobile engine 63 is divided at a predetermined ratio by a diversion valve 61, one of which is distributed to the front wheel power steering device 10.
The other is supplied to the rear wheel power steering device 20, and the used working fluid is returned to the reservoir 62.

The front wheel power steering device 10 includes a known rotary type front wheel servo valve 11 provided in the middle of a handle pongee 16 that transmits the rotation of a steering handle 15 to a rack and pinion mechanism 12 that converts the rotation of a steering handle 15 into reciprocating motion of a front wheel operating port 7 and 13. The main component is a front wheel power sill 14 provided on a front wheel operating rod 13. The front wheel servo valve 11 is the steering handle 10
The front wheel power cylinder 1 is operated from the supply pump 60 via the diverter valve 61 to the
4, the amplified steering force is output to the front wheel operating rod 13, and the left and right steering force is outputted to the front wheel operating rod 13 through the tie rod 17 and knuckle arm 18 provided at both ends. The front wheels 19 of the vehicle are steered.

The rear wheel power steering device 20 includes a rotary type rear wheel servo valve 50 and a rear wheel power steering device 24, and further includes a steering characteristic imparting mechanism 30 and an assist delay avoidance mechanism 40. As shown in FIG. 1, the input shaft 31 of the steering characteristic imparting mechanism 30 and the output shaft 51 of the rear wheel servo valve 50 are rotatably placed in the rear wheel housing 21 via bearings and spaced apart in the axial direction. supported, each rotating shaft 41A01,
02 are eccentric to each other. In addition, other members 50, 2
4.30.40 are also provided within the rear wheel housing 21. Cable length 11 in the middle! A pair of operating cables 65a and 65b provided with the adjustment device 66 are made of an inner wire and an outer tube, one end of each inner wire is connected to a projection provided at both ends of the front wheel operating rod 13, and the other end of each inner wire is connected to an input terminal. Pulley 31aI formed on the shaft 31: Wrapped around the pulley 31aI, the output shaft 31 is rotated in accordance with the reciprocating movement of the front wheel operating rod 13. Although not shown, both ends of the seven-tube tubes of the operating cables 65a and 65 are attached to the housing of the front wheel power steering device 10 (not shown) and the rear wheel housing 21, respectively. In addition, each operation cable 65a, 65b
Moreover, the front wheel operating rod 1 is not equipped with an outer tube, and is passed through a plurality of intermediate pulleys (not shown) provided on the vehicle body.
3 and the pulley 31a.

The steering characteristic imparting mechanism 30 uses a so-called Geneva mechanism, and is provided within the front end of the rear wheel side huff song 21. As shown in FIGS. 1 and 3, steering characteristics are imparted 8! An input shaft 31 of the oval 30 is supported via a bearing on a support shaft 32 fixed to the rear wheel housing 21.
A driven rotating member 33 provided opposite to the rear end surface of the output shaft 51 is rotatably supported within the rear wheel side housing song 21 around a common rotational axis 02 with the output shaft 51, and is supported in the rear wheel side housing song 21 and the assist delay avoidance Wi mechanism 40 and the rear wheel. It is connected to an output shaft 51 via a ring servo valve 50. On the rear end surface of the input shaft 31, there is a support bin 36 fixed to the rotation axis fio1 at a position eccentric by the same amount and 90 degrees different in phase from the rotation axis fio1, and protruding rearward from the rotation axis AO1. A pair of engagers 34 are provided which are freely supported rollers 35. Further, on the front surface of the protrusion 33a formed concentrically on the front side of the driven rotating member 33, a V-shape with an included angle of 90 degrees is arranged, and the outer end 37a extends in the radial direction and extends around the outer periphery of the protrusion 33a. A pair of guide grooves 37 open outward from the surface are shaped like r&. The guide groove 37 has a width that allows the outer circumferential surface of the roller 35 of the engager 34 to be engaged with the roller 35 without any gap, and the radius of the outer circumferential surface of the protrusion 33a is set such that the radius of the outer circumferential surface of the protrusion 33a is equal to the radius of the outer circumferential surface of the engager 14 relative to the rotational axis 01. It is the same as the amount of eccentricity. In addition, the steering characteristic imparting mechanism 30 has a small number of parts and each part is relatively simple, so it is easy to manufacture and only requires a small amount of manufacturing cost.

In the front wheel steering neutral state, as shown in FIG. are each corresponding guide groove 37 and extra! @37a
In this state, engagement is started. Therefore, the plane connecting the center of each engaging element 34 and the rotation axis IQO1 is orthogonal to the center plane of the guide groove 37 including the rotation axis 02. When one front wheel is steered from this state and the input shaft is rotated in accordance with the increase in the front wheel steering angle, one of the engagers 34 is first inserted into the corresponding guide groove 37 from the outside along its center plane. It enters through the outer end 37a and engages with the guide groove 37 to rotate the driven rotation member 33 in the opposite direction to the input shaft 31, and the other engager 34 moves in the direction away from the corresponding guide yt37.

The engaging element 34 first enters the guide groove 37 from the outside along the center plane through the outer end 37a, but since it moves in an arc around the rotational axis 01, the angular velocity of the driven rotating member 33 is at the front wheel steering neutral. (near the position, that is, at the beginning of the rotation of the input shaft 31) is 0, and as the rotation angle of the input shaft 31 increases, it increases continuously until the holder 34 reaches the plane connecting the two rotation axes 01 and 02. It reaches a maximum at a point in time and decreases symmetrically thereafter. In this embodiment, the rotation angle range of the input wheel 31 with respect to the neutral position is about 6 on the left and right.
0 degree, and the driven rotating member 33 is approximately 73 degrees on the left and right.
Rotate degrees. Therefore, as shown in FIG. 4, the driven rotating member 33 reaches its maximum angular velocity and reaches the limit of its rotational angle with virtually no decrease.

As shown in FIG. 1, the driven rotating member 33 has a thin cylindrical box shape consisting of two parts, front and rear, and an output rotating member 45 is supported coaxially and relatively rotatably in the rear half of the box. A rear end portion of the output rotation member 45 that protrudes rearward from the rear wheel servo valve 45 is connected to a front portion of an operating shaft 52 of a rear wheel servo valve 50, which will be described later, via a speed increasing mechanism 46. The speed increasing mechanism 46 includes a first gear 47 fixed to the rear end of the output rotating member 45 via a key and a ring nut, and an intermediate shaft 48 supported on the rear wheel housing 21 parallel to the rotating shaft #IO. The fixed @2 and third gears 48a and 48b are spline-coupled to the front end of the operating shaft 52! Consists of ¥S4 gear 49, first and second gears 47, 48a and 13, and fourth gear 4
8b and 49 are meshed with each other, and the overall speed increasing ratio is 3.

The operating shaft 52 of the rear wheel servo valve 50 is operated by the second speed increasing mechanism 46.
The rotation angle is approximately 220 degrees.

The assist delay avoidance mechanism 40 provided between the driven rotation member 33 and the output rotation member 45 is as shown in Fig. fjS1.
The main components are a spiral spring 41, an engagement boss 42 coaxially rotatably provided on the output rotating member 45, and a central shaft 43 coaxially fixed to the output rotating member 45, and both rotating members 33, 45. In the state in which no torque is applied during this period, an initial torque is applied to the spiral bone 41, and both ends of the spiral bone 41 are simultaneously engaged with parts of both rotating members 33, 45, respectively. That is, the inner end of the spiral spring 41 engages with the engagement boss 42 from one direction in the circumferential direction, and the forward and inward protrusions 42a and 42b provided on the engagement boss 42 simultaneously engage the driven rotation member 33. Four semicircular parts 3 formed on the rear surface
3a and a semicircular notch 43 formed at the front end of the central shaft 43.
It is engaged with the end face of a from one direction in the circumferential direction. Further, the outer ends of the spiral springs 41 are simultaneously engaged with protrusions 33b and 45a formed on the respective outer peripheries of the two flexible members 33.45 from opposite directions in the circumferential direction.

According to the assist delay avoidance mechanism 40 having such a configuration,
Driven and output rotating member 33. If the transmitted torque between '45 is less than the initial torque of the spiral spring 41, the rotation of the driven rotating member 33 is transmitted to the output rotating member 45, but if the transmitted torque exceeds the initial torque, the assist delay will be delayed. The avoidance mechanism 40 is activated, that is, the round spiral spring 41 is bent, and the rotation of the driven rotation member 33 is no longer transmitted to the output rotation member 45.

As shown in FIG. 2, the rear wheel power cylinder 24 includes a cylinder 25 formed on the rear wheel housing 21, and a piston that is fluid-tightly inserted into the cylinder 25 and separates the inside thereof into left and right working chambers. 26, the rear wheel actuating a-7 door 23 is fixed to the piston 26, and both ends thereof have a shilling 2
5 in a fluid-tight and slidable manner.

A pair of return springs for returning the rear wheel operating loft 23 to the illustrated neutral position are provided between both side surfaces of the piston 26 and the inner surfaces of both ends of the sill 25, and both ends of the rear wheel operating rod 23 are connected to a tie rod 27 and a knuckle arm 28. through rear wheel 2
It is designed to be rubbed dry.

The rotary type rear wheel servo valve 5o is mainly used for tI
As shown in Figure S1, it is provided in the t&wheel side housing 21 coaxially with the assist delay avoidance mechanism v140. The output wheel 51 of the rear wheel servo valve 5o and the hollow operating shaft 52 are coaxially supported by the rear wheel housing 21 and connected to each other by a tone member 56 so as to be relatively rotatable. A binion 22 formed at the rear of the output wheel 51 meshes with a rack 23a formed on the rear wheel operating rod 23, and a fourth gear 49 of a speed increasing mechanism 46 is splined to the front end of the operating shaft 52. A rotor valve member 53 of the rear wheel servo valve 50 is formed in a part of the operating shaft 52.
The inner and outer circumferences of the sleeve valve member 54 are rotatably fitted to the outer circumference of the rotor valve member 53 and the inner circumference of the rear wheel side brake song 21, respectively, and are connected to the output shaft 51 via a pin 55. These two valve members 53 and 54 form an oven center type 4-port throttle switching valve, and when the input torque applied to the operating wheel 52 is O, the rotor valve member 53 and the sleeve valve member 5
When the relative rotation angle of 4 is O, the working fluid supplied from the supply pump 60 to the input port 50a via the diversion valve 61 is directly discharged from the discharge port 50b to the reservoir 62. However, if the input torque applied to the operating wheel 52 increases and relative rotation occurs between the two valve members 53,54,
Depending on its direction and relative rotation angle, the working fluid supplied to the input cup (50a) is introduced into one working chamber of the power cylinder 24 from either one of the two distribution bows (50c, 50d), and the other The working fluid in the room is discharged from the other distribution boat to the reservoir 62 via the discharge boat (Sob) to amplify the steering force to the two rear wheels.

Next, the overall operation of the above embodiment will be explained.

If the steering handle 15 is rotated clockwise as shown by the arrow in FIG. 2, the front wheel power steering system is activated! 110 operates as described above, and the front wheel operating rod 13 moves rightward as shown by the arrow, and steers the left and right front wheels 19 rightward via the tie rod 17 and knuckle arm 18. At the same time, the inner wires of the operating cables 65a and 65b move in the direction shown by the arrow, and rotate the pulley 31a and input shaft 31 of the rear wheel power steering device g20 in a clockwise direction as viewed from the rear in response to the steering of the front wheels 19. do. When the steering wheel 15 is rotated counterclockwise in the opposite direction to the arrow, each part operates in the opposite direction to the above, the front wheel 19 is steered to the left, and the boot 1731a and input shaft 31 are rotated counterclockwise when viewed from the rear. be rotated.

No matter which direction the input shaft 31 is rotated, the angular velocity of the driven rotating member 33 is ro near the IW wheel steering neutral position, as described above, and continues as the rotation angle of the input shaft 31 increases. increases and rotates in the opposite direction. In a normal state, the torque transmitted between the driven rotating member 33 and the output rotating member 45 is small, so the assist delay avoidance mechanism 40 does not operate, and the driven rotating member 33 rotates accordingly.
The output is transmitted to the rotating member 45 and operates the rear wheel servo valve 50 via the speed increasing mechanism 46. Front wheel 1 from steering neutral state
When the steering characteristic imparting mechanism 30. The operating wheel 52 and output shaft 51 of the rear wheel servo valve 50 rotate counterclockwise through the assist delay avoidance mechanism 40 and the speed increasing fi horizontal 46, and the rear wheel operating rod 23 rotates in the direction of the arrow through the rack 22 and pinion 23a. Move to the right as shown. Also, at this time, the rear wheel servo valve 50 operates according to the operating torque input to the operating wheel 52, and the operating fluid from one distribution boat 50C is supplied to the left operating chamber of the rear wheel power cylinder 24. The rightward steering force generated on the wheel actuating rod 23 is amplified. The left and right rear wheels 29 are steered leftward in response to rightward steering of the front wheels 19 via tie rods 27 and knuckle arms 28 provided at both ends of the rear wheel operating rod 23. Furthermore, if the front wheels 19 are steered to the left, each part operates in the opposite direction to the above, and the rear wheels 129 are steered to the right. With the operation of the rear wheel servo valve 50, the operating wheel 52 and the output shaft 51 rotate relative to each other in proportion to the operating torque, but since the relative rotation angle is small, the rear wheel 29 relative to the steering angle of one front wheel The characteristics of the steering angle are as shown in FIG. 4, similar to the rotation angle of the driven rotating member 33. In other words, the rear wheels 29 are hardly steered near the front wheel steering neutral position, but as the front wheel steering angle increases, the four steering angular speeds of the rear wheels 29 increase continuously from around O as the front wheels are steered. is steered in the opposite phase.

As described above, according to the above embodiment, the rear wheels 29 are hardly steered and are maintained in a neutral state when driving at high speeds when the steering angle of the front wheels 19 is small, and when driving at low speeds when the steering angle of the front wheels is large, the rear wheels are steered. A favorable rear wheel steering characteristic with an increased angle is obtained.

In the above embodiment, if the phase angle between the two engaging elements 34 is set to 90 degrees or more, the engaging element 34 and the guide groove 34 will not engage until the input shaft 31 rotates a little from the front wheel steering neutral state. , during which the two rear wheels are not steered at all, and the steering angular velocity of the rear wheels then increases from O. Also, Geneva 15 used for the steering characteristic imparting mechanism 30! The structure is not limited to one in which the angle between the guide grooves 37 is 90 degrees as shown in the figure, but any structure having an arbitrary angle can be used.

Note that in a state where the rear wheel 29 has fallen off into a groove or the like and its steering is blocked, rotation of the output shaft 51 is also blocked, so the rotation angle of the steering handle 15 must be increased. The stopper between the output #51 and the construction gJ'J pongee 52 comes into contact immediately, and the rotation of the operating shaft 52 is also prevented. In this state, if the rotation angle of the steering handle 15 is increased further, the driven rotating member 33 will rotate further, but this rotation is absorbed by the deflection of the spiral spring 41, and therefore Unreasonable force is applied to each operating cable 6.
It is not added to the inner wires of 5a and 65b. Therefore, the initial torque of the spiral spring 41 is set to be as large as possible within a range that does not pose a problem for the above-mentioned operation, so that there is no risk of each inner wire being stretched or damaged.

Note that the present invention can also be implemented using front and rear wheel steering devices that do not rely on a power steering device.

[Brief explanation of the drawing]

1 to 4 show an embodiment of a four-wheel steering device according to the present invention, in which FIG. 1 is a vertical sectional view of the main part, FIG. 12 is a schematic plan view of the whole, and FIG. FIG. 4 is a cross-sectional view taken along line 1--2 of FIG. Explanation of symbols 10...front wheel steering device (front wheel power steering r) device),
20... Rear wheel steering device (rear wheel power steering device), 2
DESCRIPTION OF SYMBOLS 1... Rear wheel side... Usong, 30... Steering characteristic imparting mechanism, 31... Input shaft, 31a... Pulley, 33...
...Followed rotating member, 34...-engaging element, 37... Guide groove, 37a... Outer end, 51... Output shaft, 65a, 6
5b...operation cable, 01.02...rotation axis line.

Claims (1)

[Claims] A front wheel steering device that steers a front wheel, and a rear wheel steering device that steers a rear wheel, the rear wheel steering device having an input shaft to which the operation of the front wheel steering device is transmitted via a transmission device;
In a four-wheel steering device comprising an output shaft connected to the input shaft to steer the rear wheels in conjunction with the front wheels, the input shaft and the output shaft are respectively rotated within the rear wheel side housing of the rear wheel steering device. a driven rotating member that is arranged and supported in the axial direction, has a rotational axis eccentric to the rotational axis of the input shaft, is provided facing an end face of the input shaft, and is connected to the output shaft; a pair of guide grooves arranged in a V-shape on a surface facing the input shaft of the driven rotating member, each extending in a substantially radial direction, and having an outer end open from the outer circumferential surface of the driven rotating member; The guide grooves are provided so as to protrude from the end faces of the input shafts, have the same eccentricity from the rotational axis of the input shafts, and are inserted into the corresponding guide grooves in accordance with the rotation of the input shafts in the direction of the center plane thereof. A steering characteristic imparting mechanism comprising a pair of engagers that alternately enter through the open outer end and are engaged with the guide groove to transmit the rotation of the input shaft to the driven rotation member. A four-wheel steering device.