JPH035280A - Four-wheel steering device - Google Patents

Abstract

PURPOSE:To prevent application of unreasonable force on operation cables in the case of generation of assist delay by providing a wire conversion part having a steering characteristic adding function and an assist delay avoidance function, between a pair of operation cables transmitting the operation of a front wheel steering device to a rear wheel steering device. CONSTITUTION:A pair of operation cables 65, 66 transmitting the operation of a front wheel steering device to a rear wheel steering device, are separated into front half parts 65a, 66a and rear half parts 65b, 66b, and a wire conversion part 30 is provided between them. The wire conversion part 30 is provided with input and output side pulleys 32, 33 rotatably supported on both end parts in a casing 31, and the input side pulley 32 has a cam groove 34 consisting of a pair of outside groove parts 34b, 34c on its end face, and the output side pulley 33 has similarly a cam 35. A transmitting member 40 of which the distance between a pair of projections 40a, 40b projected from both ends in the axial direction is changed at applied force between both projection over a prescribed value, is provided, and engaging elements 48, 49 on respective extreme ends of projections are engaged with respective cam grooves 34, 35.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention links a front wheel steering device and a rear wheel steering device via a pair of wires to steer the rear wheels according to the steering angle of the front wheels. The present invention relates to a four-wheel steering device.

(Prior art) As this type of four-wheel steering device, for example,
52578, this technology uses a complicated coupling mechanism and drive 8! in order to change the rear wheel steering characteristics according to the vehicle speed. It has a structure.

(Problems to be Solved by the Invention) For this reason, the above-mentioned conventional technology has a bulky and complicated structure as a whole. In addition, in the above-mentioned conventional technology, for example, if the rear wheel falls off into a groove or the like and steering is blocked, unreasonable force is applied to the wire when trying to turn the steering wheel with force, causing the wire to stretch or break. There is a risk of In addition, in this type of four-wheel steering system, it is possible to provide a rear wheel power steering system consisting of a rotary servo valve and a power sill, and rotate the input shaft of the rotary servo valve using the wire, but the rotary servo valve The operating wheel and the output shaft are connected by a torsion bar, and a manual stopper is provided between the two shafts to limit the relative rotation angle within a predetermined small range, so that the rear wheel does not fall into a groove. When the wheels come off and steering is blocked, the manual stopper comes into contact with it almost immediately, and if you try to turn the steering wheel with force, excessive force is applied to the wire, which may stretch or break the wire. . Further, a similar problem occurs when an assist delay occurs in which the rear wheel steering does not keep up with the front wheel steering for some reason. In order to avoid such problems, it is conceivable to incorporate an assist delay avoidance mechanism into the housing of the rear wheel steering device.

However, because the rear wheel steering device with the built-in assist delay avoidance mechanism becomes larger, the machining cost of the haunong increases, and there may be restrictions on the arrangement of the rear wheel steering device and its surrounding parts. .

The present invention provides rear wheel steering characteristics 8! A wire conversion section equipped with a function and an assist delay avoidance function is provided in the middle of the operating cable to provide the desired rear wheel steering characteristics and to prevent excessive force from being applied to the operating cable in the event of an assist delay. It is an object of the present invention to provide a four-wheel steering device that has a small processing cost such as a hounong and is easy to arrange.

(Means for Solving the Problems) For this purpose, the four-wheel steering device according to the present invention includes a front wheel steering device 1 for steering the front wheels, as illustrated in FIGS. 1 to 5.
0, and a rear wheel steering device 20 that steers the rear wheels, and the operation of the front wheel steering device 10 is transmitted through a pair of operating cables 65, 66 and a pulley 69 to this rear wheel steering device to steer the rear wheels. In a four-wheel steering device comprising an input shaft 52 that steers in conjunction with the input shaft, the pair of operation cables 65.6d are separated into a pair of front half portions 65a, 66a and a pair of rear half portions 65b, 66b. A casing 31 and a front half 65a, 66a and a rear half 65b, 66 supported rotatably around mutually parallel axes 01, 02 at both ends within the casing, respectively.
An input pulley 32 and an output pulley 33 that rotate in conjunction with the front wheel steering device 10 and the rear wheel steering device 20 via b, and a pulley formed on the end face of the input pulley and centered around the input pulley fio1. An arc-shaped central groove 3
4a and a pair of outer groove portions 34b and 34c whose radial position from the coaxial line symmetrically increases or decreases as the distance from both ends of the input side cam groove 3 is increased or decreased in each direction in the circumferential direction.
4, and an output side cam groove 35 formed on the end surface of the output side boob 933, in which the radial position from the thin wire 02 of the output side pulley increases or decreases symmetrically as it moves away from the center in each direction in the circumferential direction. , a pair of protrusions 4 that are movably guided and supported by the casing 31 in the direction connecting the two axes Mol, 02 and protrude from both ends in the direction of each axis 01.02.
A transmission member 40 that does not change when the distance between 0a and 40b is less than a predetermined value and expands and contracts by the force when the force applied between the two protrusions exceeds a predetermined value; The present invention is characterized in that a wire converting portion 30 is provided, which is comprised of an input-side engager 48 and an output-side engager 49 that engage with the input-side cam groove 34 and the output-side cam groove 35, respectively.

(Function) In a state where no assist delay occurs, the input shaft 52
Since the torque generated in is small, both protrusions 4 of the transmission member 40
The force applied between 0a and 40b is small, and the distance therebetween does not change. In this state, the front wheel steering device 10 is operated by the front half portions 65a, 66a of the operation cables 65°66.
, input side pulley 32, input side cam groove and engaging elements 34, 4
8. Transmission member 40, output side engager and cam groove 49, 35
, directly via the output pulley 33 and the rear parts 65b and 66b of the operation cables 65 and 66) Rear wheel steering device 2
0 input shaft 52. In this state, the input side engager 48 is connected to the center groove 34 near the front wheel steering neutral position.
In the range within a, the rear wheels are held in a neutral state, and the front wheel steering angle increases so that the input side engager 48 moves toward the outer groove portion 34b.
, 34c, the rear wheels are steered according to the front wheel steering angle. If the steering wheel is turned any further in a state where the rear wheels are no longer being steered for some reason or there is a delay in assist, both protrusions 40a and 4ob of the transmission member 40
The force applied between them increases, and if this force exceeds a predetermined value, the distance between the protrusions 40a, 4Ob changes, and the rotation of the input pulley 32 is no longer transmitted to the output pulley 32. Therefore, generation of excessive force on the operating cables 65, 66 is prevented. In addition, since the wire conversion unit 30 equipped with such a rear wheel steering characteristic imparting function and an assist delay avoidance function is installed in the middle of the operation cable 65.6 (3), the rear wheel steering device 20 can be replaced with the same small size as the conventional one. becomes.

(Effects of the Invention) As described above, according to the present invention, desired rear wheel steering characteristics can be provided, and even if the rear wheels are no longer steered or an assist delay occurs, unreasonable force is not applied to the operation cable. There is no risk of the operation cable being stretched or damaged.

Since the separate wire conversion section is provided in the middle of the flexible operation cable, its arrangement can be freely determined.

Furthermore, since both the housing of the rear wheel steering device and the casing of the wire conversion section are small, the total processing cost can be reduced compared to the case where they are integrated.

(Example) The present invention will be explained below using examples shown in FIGS. 1 to 5.

As shown in Figure tlIJ3, in this embodiment, power steering devices are used as the front wheel and rear wheel steering devices 10 and 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 supplied to the front wheel power steering device 10. , the other is supplied to the rear wheel power steering device M20, 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 rotation of a steering handle 15 to a rack binion mechanism 12 that converts rotation of a steering handle 15 into reciprocating motion of a front wheel operating rod 13, and a front wheel servo valve 11 of a known rotary type. The main component is a front wheel power sill 14 provided on the 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. A pair of operation cables 65, 66 that interlock the front and rear power steering devices 1.0.20 are separated into front parts 65a, 66a and rear parts 65b, 66b.
A wire conversion section 30 is provided for converting the strokes of the half portions 6a and 65b, 66b, and cable length adjustment devices 67, 68 are provided in the middle of each half. Each operating cable 65, 66 consists of an inner wire and seven outer tubes, the front end of each inner wire is connected to a protrusion provided at both ends of the front wheel operating rod 13, and the rear end of each inner wire is an input shaft of the rear wheel power steering device 20. Although not shown, each operating cable 65 and 66 is wound around a pulley 69 provided at
Both ends of the 7 outer tubes are attached to a housing (not shown) of the front wheel power steering device 10 and a housing 21 on the rear wheel side, respectively. In addition, each operation cable 65
．． 66 may not be provided with such an outer tube, but may be stretched between each protrusion of the front wheel operating rod 13 and the pulley 69 through a plurality of intermediate pulleys (not shown) provided on the vehicle body.

As shown in FIGS. 1 and 2, the wire conversion g30 has an input side boo 1732 provided in the casing 31, an output side pulley 33, and a transmission member 40 as main components. At both ends inside the casing 31, there are axes 0 parallel to each other.
An input pulley 32 and an output pulley 33 are supported via pongee sleeves 36 and 37 which are rotatably rotated around 1 and 02.

The rear ends of the inner wires of the front half portions 65, 66a of the operation cables 65, 66 are fixedly wrapped around the input pulley 32 from both sides, and the front ends of the inner wires of the rear half portions 65b, 66b are fixedly wrapped around the output pulley 33 from both sides. The corresponding ends of the seven tubes of each half are respectively attached to the casing 31.

As mainly shown in FIG. 2, a part of the outer circumferential surface of the input pulley 32 has an axis 0 extending from the center in both circumferential directions.
Cam surfaces 3 and 2b are formed whose distance from 1 increases symmetrically. The casing 31 is perpendicular to the axis 01.
A sliding body 38 is supported by the support tube 31b fixed to the support tube 31b, and this slide body 38 is biased in the direction of the axis o1 by a spring 38a provided between the support tube 31b and the roller 39 provided at the tip of the slide body 38. is being pressed. - As a result, the input pulley 32 is held at the neutral position shown in the figure when no force is applied from the outside. The inner end surface 32a of the input pulley 32 has an arc-shaped central groove 32a centered on the axis 01, and a pair of outer grooves 34b extending outward in the circumferential direction from both ends thereof at the same angle.
, 34c, and an input side cam groove 34 having a constant width as a whole is formed. In the illustrated neutral state, the angular range α of the central groove 34a is symmetrical with respect to the plane connecting both sleeves moi, 02, and the shape of each outer groove 34b, 34c is as follows.
As the grooves move outward in the circumferential direction, the radial position from the axis O1 gradually increases with respect to one outer groove portion 34b, and decreases with respect to the other outer groove portion 34c in a symmetrical manner. Further, an output side cam groove 35 having a constant width is formed on the inner end surface 33a of the output side boob 933. In the illustrated neutral state, the angular range of the output side cam groove 35 is also symmetrical with respect to the plane connecting both axes 01.02, and as it moves away from the center in the circumferential direction, the radius from the axis #lo2 increases. The directional position increases and decreases exactly symmetrically.

Next, the transmission member 40 including a pair of protrusions 40a and 40b will be explained. A cylindrical sliding body 41 is fitted and supported so as to be movable in the axial direction in a hole 31a formed in the middle part of the casing 31 so as to be orthogonal to the two axes 01.02 and in a direction connecting them. .

A rod 42 is slidably inserted into the center of a pair of seven-run members 44, 44 that are slidably provided inside the sliding body 41, and a pair of ring stoppers are provided at a distance from the rod 42. 44a, 44a are provided, and both 7 lunge members 4
A compression spring 45 is interposed between 4.44 and each seven run member 44 is brought into contact with each ring stopper 44a with a considerable initial load.

A stopper 43a screwed into the inside of the sliding body 41 from both ends
, 43b are fixed by lock nuts 43c at positions where each tip just contacts the corresponding seven-run member 44. One end of the rod 42 slidably passes through the stopper 43a and extends outward to form an input side protrusion 40a, and the stopper 43b is integrally provided with an output side protrusion 40b extending in the opposite direction to the protrusion 40a. ing. Each protrusion 40a, 4
0b, the tips of engagement pins 46 and 47, which are provided upright from the casing 31, are engaged with guide/inside grooves 46a and 47a formed in the longitudinal direction to prevent rotation.

The tip of the protrusion 40a on the input side has a pongee lF! An input side engager 48 is provided in which the inner ring of a ball bearing 48a is fitted into a pin 48b that stands parallel to the pin 48b. are doing. A similar output side engager 49 consisting of a pin 49b and a ball bearing 49a is also provided at the tip of the output side protrusion 40b, and the outer peripheral surface of the outer ring of the ball bearing 49a engages with the output side cam groove 35 with virtually no gap. It matches.

The rear wheel power sill 24 has a sill 25 formed on the rear wheel housing 21 as shown in FIG. 3, and is fitted into this sill 25 in a fluid-tight manner so that the inside thereof is divided into left and right working chambers. The rear wheel actuating rod 23 is fixed to the piston 26, and both ends of the rod 23 protrude from both ends of the sill 25 so as to be slidable at i[ffi. A pair of return springs for returning the rear wheel operating rod 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. Rear wheel 29 through
It is designed to steer.

The rotary type rear wheel servo valve 50 mainly has a fourth
As shown in the figure, it is provided in the rear wheel side)) unong 21. Output shaft 51 of rear wheel servo valve 50 and hollow input shaft 5
2 is a rear wheel side hose song 2 that can be rotated coaxially relative to each other.
1 and connected by a torsion bar 56, and a manual stopper 58 is provided between the shafts 51 and 52 that allows relative rotation only through a relatively small angle (for example, 5 degrees left and right) about the neutral position. It is provided. A binion 22 formed at the rear of the output shaft 51 is connected to the rear wheel operating rod 2.
The input shaft 5 is engaged with the rack 23a formed in the input shaft 5.
A pulley 69 is splined to the front end of 2.

A rotor valve member 53 of the rear wheel servo valve 50 is formed in a part of the input shaft 52, and a sleeve valve member 5 of the rear wheel servo valve 50 is formed on a part of the input shaft 52.
The inner and outer circumferences of the bottle 5 are rotatably fitted to the outer circumference of the rotor valve member 53 and the inner circumference of the rear wheel side hose song 21, respectively.
It is connected to an output shaft 51 via 5. These two valve members 53 and 54 form an open center type four-boat switching valve, and when the input torque applied to the input shaft 52 is 0, the relative rotation angle between the rotor valve member 53 and the sleeve valve member 54 is 0.
In this case, the working fluid supplied from the supply pump 60 to the input port 50a via the diversion valve 61 is discharged from the discharge boat 50b to the reservoir 62. However, because
As the input torque applied to the actuating shaft 52 increases, both valve members 53
．． If a relative rotation occurs between the power cylinders 24 and 54, the working fluid supplied to the inlet cup 50a is transferred to the power cylinder 24 from either of the two distribution bows 50c and 50d depending on the direction and relative rotation angle. into one working chamber, and discharge the working fluid in the other working chamber from the other distribution port) 50b
The steering force to the rear wheels 29 is amplified by discharging the fuel into the reservoir 62 through the .

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. 17 and knuckle arm 18 to steer the left and right front wheels 19 to the right.At the same time, the inner wires of the protruding halves 65a and 66a of the operation cables 65 and 66 move in the direction shown by the arrow to input the wire converter 30. The side pulley 32 is rotated counterclockwise in FIG.

If you turn the steering wheel 15 counterclockwise in the opposite direction of the arrow,
Each part operates in the opposite direction to the above, the front wheel 19 is steered leftward, and the input pulley 32 is rotated clockwise in FIG. 2. When the input pulley 32 rotates, the transmission member 4
0 protrusion 40a moves in the axial direction, and the protrusion 40b on the opposite side moves in the axial direction.
The output pulley 33 attempts to rotate via the output side engager 49 provided in the output side cam groove 35.

When there is no abnormality in the rear wheels 29 and the rear wheels 29 are steered according to the steering of the front wheels 19, that is, when there is no assist delay, the resistance torque generated on the input shaft 52 is small, so that the pulley 69 and the operation cables t35, 6f3 are Second half 6
The output pulley 33 connected via 5b and 66b rotates easily. Therefore, both protrusions 40a, 4 of the transmission member 40
Since the force applied between 0b is small and the distance therebetween does not change, the rotation of the input pulley 32 is transmitted to the output pulley 33 via the transmission member 40. If the rotation angle of the input pulley 32 is within the predetermined range α from the neutral position and the input side engager 48 is within the arc-shaped central groove 34a centered on the axis 01, the transmission member 40 will not move. The output pulley 33 does not rotate from the neutral position, and the rotation angle of the input pulley 32 increases, causing the input side engager 48 to move toward the outer grooves 34b, 3.
4c, the transmission member 40 moves and the input pulley 3
The output pulley 33 comes to rotate in accordance with the rotation of the output pulley 2. Therefore, the rear parts 65b, 6 of the operating cables 65, 66
6b, the stroke of the front half 65a is as shown in FIG.
, 66a does not move within a predetermined range α centered on the neutral position, and if it falls outside this predetermined range, the first half ti6
It has a characteristic of moving according to the strokes of 5a and 66a. The stroke of this rear half 65b, 66b is the pulley 69
The power is transmitted to the input shaft 52 via the rear wheel power steering device 2.
Make 0! +! Since the steering angle is JJ, the characteristics of the rear wheel steering angle with respect to the front wheel steering angle are also as shown in FIG. This characteristic is
By changing the shape of the cam grooves 34 and 35, it is possible to obtain the desired shape.

In this normal operating state, if the front wheel 19 is steered to the right, the front half portions 65a, 6 of the operating cables 65, 66
6a, the input shaft 52 and output shaft 51 of the rear wheel servo #50 are rotated in a counterclockwise direction when viewed from the rear via the wire converter 30 and the rear half portions 65b and 66b, and Move the wheel operating port/door 23 to the right as shown by the arrow. Also, at this time, the rear wheel servo valve 50 operates according to the operating torque input to the input shaft 52,
The working fluid from one distribution port 50c is supplied to the left working chamber of the rear wheel power ring 24, and the rightward steering force generated in the rear wheel working ring 23 is amplified. The two left and right rear wheels are steered leftward in response to rightward steering of the front wheel 19 via tie rods 27 and knuckle arms 28 provided at both ends of the rear wheel operating loft 23. Furthermore, if one face wheel is steered to the left, each part operates in the opposite direction to the above, and the two rear wheels are steered to the right. i.e. rear wheel 2
The two wheels are steered in opposite phases in response to the steering of one front wheel.

In a state where the rear wheel 29 has fallen off into a groove or the like and its steering is blocked or an assist delay occurs, rotation of the output shaft 51 is also blocked or delayed. Therefore, if the rotation angle of the steering handle 15 is increased, the output shaft 51 and input shaft 52
The manual stopper 58 between the two immediately contacts the input shaft 5.
The rotation of the output pulley 33 connected thereto via the second and rear half portions 65b and 66b is also prevented. In this state, if the rotation angle of the steering handle 15 is increased further, the input pulley 32 of the wire conversion section 30 will rotate further, but this rotation is caused by the compression spring 4 of the transmission member 40.
5 is absorbed by the deflection of the compression spring 45, and therefore, an unreasonable force exceeding that due to the spring force of the compression spring 45 is applied to each operating cable 65, 66.
It does not join the inner wire. Therefore, there is no risk of each inner wire being stretched or damaged.

Further, in the above embodiment, since the wire conversion section 30 having the assist delay avoidance function and the rear wheel steering characteristic imparting function is provided in the middle of the operation cable, the rear wheel power steering device W12
0 is substantially the same as the conventional one, and the arrangement is not more difficult than the conventional one, and the wire conversion part 30 is also provided in the middle of the visible operation cable 65, 66, so the arrangement is Be free. Furthermore, since both the rear wheel housing 21 and the housing 31 of the wire conversion section 30 are small, the total processing cost is lower than when the two are integrated.

In the above embodiment, the rear wheels 29 are steered in the opposite phase to the front wheels 9, but a normal phase/reverse phase switching mechanism is provided before and after the wire converter 30 to steer the rear wheels 29 in a phase opposite to that of the front wheels 9. Alternatively, the steering characteristics between the front and rear wheels may be changed. Furthermore, 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 5 show an embodiment of the four-wheel steering device according to the present invention, FIG. 1 is a longitudinal cross-sectional view of the wire converting section which is the main part of the present invention, and FIG. 2 is a casing of the wire converting section. 3 is a schematic plan view of the whole, FIG. 4 is a vertical sectional view of the main part of the rear wheel power steering device, and FIG. 5 is an explanatory diagram of the four rear wheel steering characteristics. Explanation of symbols 10...Front wheel steering device (front wheel power steering device), 20
... Rear wheel steering I) device (f & wheel power steering device r!ri,
30... Wire conversion section, 31... Casing, 32
...Input side pulley, 33...Output shaft pulley, 32a
, 33a... end face, 34... input side cam groove, 34a...
... Central groove, 34b, 34c... Outer groove, 35.
・・Output side cam groove, 40 ・・Transmission member, 40a,
40b-Protrusion, 48... Input side engager, 49... Output side engager, 52... Input shaft, 65.66... Operation cable, 65a, G6a... First half, 65b, 66
b...Late half, 01,02...Axis line.

Claims (1)

[Claims] The rear wheel steering device includes a front wheel steering device that steers the front wheels and a rear wheel steering device that steers the rear wheels. In the four-wheel steering device, the pair of operation cables are separated into a pair of front parts and a pair of rear parts, and a casing is disposed between the front part and the rear part. An input-side pulley and an output-side pulley that are rotatably supported around mutually parallel axes at both ends within the casing, and rotate in conjunction with the front wheel steering device and the rear wheel steering device via the front and rear portions, respectively. A pulley, an arc-shaped central groove formed on the end face of the input pulley and centered on the axis of the input pulley, and a radial position from the coaxial line that becomes symmetrical as it moves away from both ends of the pulley in each direction in the circumferential direction. An input cam groove consisting of a pair of outer grooves that increases or decreases, and an input cam groove formed on the end face of the output pulley whose radial position from the axis of the output pulley becomes symmetrical as it moves away from the center in each direction in the circumferential direction. The distance between the output side cam groove, which increases or decreases, and a pair of projections that are movably guided and supported by the casing in the direction connecting the two axes and protrude from both ends in the direction of the respective axes is the force applied between the two projections. a transmission member that does not change when the force is less than a predetermined value and expands and contracts due to the force when it exceeds a predetermined value; and an input member that is provided at the tip of each of the protrusions and engages with the input cam groove and the output cam groove, respectively. A four-wheel steering device characterized by being provided with a wire conversion section consisting of a side engagement element and an output side engagement element.