JPH0147349B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering device equipped with a plate type valve mechanism.

Conventional power steering devices are provided with rotary or spool type valve actuation mechanisms, but these valve mechanisms themselves are complex and relatively long, and the valve configuration requires high precision. It had the disadvantage of being large and expensive.

The present invention is completely different from conventional rotary type or spool type valve actuation mechanisms which have such drawbacks. This paper proposes a power steering device with a plate type valve mechanism.The purpose is to simplify and downsize the configuration of the valve mechanism, and to provide a power steering device that is easy to process and inexpensive. . In addition, it effectively prevents vibrations of the entire valve mechanism caused by the flow of hydraulic oil.
Another object of the present invention is to provide a power steering device that provides an excellent steering feeling.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a main part of a power steering device showing an embodiment of the present invention. That is, the piston 1 separates the inside of the cylinder 2 into two working chambers 3.4, and the piston 1 is provided with a rack 1a.
It is engraved on the sector shaft 5 that drives a control link (not shown), meshes with the sector gear 5a, and is provided on the housing body 6b that constitutes the rear housing 6 that seals one end of the cylinder 2 together with the retaining plate 6a. A power steering device that selectively supplies and discharges hydraulic oil to the working chambers 3 and 4 through a supply hole 7 and a discharge hole 8 to assist rotation of a sector shaft 5 connected to the piston 1, The wormshaft 9 passes through the rear housing 6 in a liquid-tight manner, and has one end connected to the piston 1 by a ball screw 10, and the other end connected to the rear housing 6 with a bearing 11,
It is rotatably supported via 12. Also,
As shown in FIG. 2, the head 9a at the other end of the wormshaft 9 is provided with a long groove 9c in the radial direction into which a bearing hole 9b and a flange 13a of a stub shaft 13, which will be described later, are inserted. Furthermore, the head 9a
Two sets of oil passages 9d and 9e for hydraulic oil with a desired pitch diameter are opened at the end face of the oil passage 9.
d directly to the working chamber 3, and the other oil passage 9e passes through the space 12a in which the bearing 12 is mounted, and further through a passage 6c in the housing body 6b constituting the rear housing 6 and a passage 2a in the cylinder 2. It communicates with the working chamber 4. 9f is wormshaft 9
This is a pin that is implanted in the worm shaft 9 and rotatably connects the worm shaft 9 and a first plate 19, which will be described later, together.

A stub shaft 13 has one end connected to a steering wheel (not shown), and the stub shaft 13 has a bearing 14 placed in the bearing hole 9b of the wormshaft 9 and a rear cover screwed onto the end of the rear housing 6. A torsion bar 17 is rotatably supported by a bearing 16 in 15 and has flexibility.
It is connected to the wormshaft 9 via. 17a and 17b are pins that respectively fix both ends of the torsion bar 17. 18 is a shaft seal that seals the stub shaft 13.
Further, as shown in FIG. 2, the stub shaft 13 has at least one (in the embodiment, two axially symmetrical)
A radial flange 13a is provided, and is loosely fitted into the long groove 9c of the wormshaft 9 with a desired clearance in the rotational direction. Therefore, even if hydraulic oil is not supplied to the working chambers 3 and 4 due to a failure of the pump or the like, the rotational force of the steering wheel is transmitted to the worm shaft 9 with a slight play angle, so that the so-called normal Manual operation is now possible. Furthermore, a drive pin 13b is implanted in the shaft portion of the stub shaft 13 in the radial direction, and this drive pin 13b connects the stub shaft 13 and a second plate 20, which will be described later, so as to be integrally rotatable.

19, one side of which is the head 9 of the wormshaft 9;
Contact the end surface a, and press the wormshaft 9 with the pin 9f.
As shown in FIGS. 3 and 4, this first plate 19 has a center hole 19a into which the stub shaft 13 is loosely fitted, and a pin 9f into which the pin 9f is inserted. A slot 19c that does not obstruct the passage of the drive pin 13b installed in the stub shaft 13 during assembly, and two sets of holes opening into the oil passages 9d and 9e of the wormshaft 9, respectively. Approximately rectangular oil path 1
8d and 19e are formed.

A second plate 20 is located between the first plate 19 and a third plate 21 to be described later, is inserted into the stub shaft 13, and is rotatable integrally with the stub shaft 13 by the drive pin 13b. As shown in FIGS. 3 and 5, this second plate 20 has a center hole 20a for inserting the stub shaft 13 and a slot 20 for inserting the drive pin 13b.
b, a pair of cut-out oil passages 20c that open the hydraulic oil supply hole 7 and do not necessarily need to be open to the outer periphery, and a central hole 20a that communicates with the discharge hole 8. Two pairs of notch-shaped oil passages 20d that do not require opening are formed. Here, in a standard state in which the stub shaft 13, that is, the second plate 20 connected thereto, is not rotated, the oil passages 20c and 20d are as shown in FIG.
A portion of the oil passages 19d and 19e of the first plate 19 communicate with each other, preferably with the same opening area, and a portion between the oil passages 20c and 20d is connected to the oil passages 19d and 19e of the first plate 19. Most of the opening area of the oil passage 19e is covered, and preferably the oil passage 1
The total covered area of oil passages 9d and the total covered area of oil passages 19e are made equal. Note that the drive pin 13b provided on the stub shaft 13 and the slot 20b of the second plate 20 into which it is inserted are connected to the second drive pin 13b.
If the plate 20 is press-fitted and fixed to the stub shaft 13, these can be eliminated.

A third plate 21 has one side facing the second plate 20 and is rotatably supported on the housing 6 via a thrust bearing 22 placed on the left end of the rear cover 15. A through hole 21a is provided in the center of the plate 21,
The stub shaft 13 is inserted through the through hole 21a, and the oil passage 20d of the second plate 20 is inserted through the through hole 21a.
It communicates with the discharge hole 8 through the bearing gap of the thrust bearing 22, and also serves as an oil passage for hydraulic oil. Further, the outer periphery of the third plate 21 is provided with a seal ring 23 having a rectangular cross section and preferably made of a synthetic resin material (for example, Teflon (trade name)).
In addition to sealing the hydraulic oil between the inner circumferential surface of the plate and the inner circumferential surface of the plate, it also serves to effectively prevent vibrations of each plate caused by the flow of the hydraulic fluid flowing through each oil passage of each plate.

On the other hand, the axial gaps between the second plate 20 and the first plate 19 and between the third plate 21 are formed, for example, in order to seal the hydraulic oil and make the rotation of the second plate 20 smooth. Although it has to be controlled to about 0.01 mm, this can be adjusted by changing the screwing amount of the rear cover 15 into the rear housing 6, and this adjusted position is held by the lock nut 24. Note that 25 is an annular chamber formed in the rear housing 6 and communicates with the supply hole 7 and the oil passage 20c of the second plate 20, and 26 is an annular chamber that also communicates with the discharge hole 8 and the through hole 21a of the third plate 21. It is. Further, the supply hole 7 and the discharge hole 8 are in communication with a pump and a reservoir (not shown), respectively.

In this configuration, in a standard state in which the steering wheel (not shown) is not rotated, the stub shaft 13 and the second plate 20 connected thereto do not rotate, and the oil passages 19d, 19e of the first plate 19 and The relative position of the second plate 20 with the oil passages 20c, 20d is at the standard position shown in FIG. Therefore,
Hydraulic oil is supplied from a pump (not shown) through the supply hole 7.
The oil passages 19d, 19 of the first plate 19 extend from the annular chamber 25 to the oil passage 20c of the second plate 20, and further open partially to the oil passage 20c.
Leading to e. These oil passages 19d and 19e communicate with the working chambers 3 and 4 in the cylinder 2 via the oil passages 9d and 9e of the worm shaft 9, respectively, so that the hydraulic oil does not try to flow into the working chambers 3 and 4. However, the oil passage 19 of the first plate 19
d and 19e simultaneously open a portion of them to the oil passage 20d of the second plate 20, so that the hydraulic oil flowing into the oil passages 19d and 19e of the first plate 19 flows into the oil passage 20d of the second plate 20. As a result,
The water is drained from the discharge hole 8 to a tank (not shown) through the through hole a of the third plate 21 and the passage 26, so that no hydraulic pressure is generated in the working chambers 3 and 4.

On the other hand, with the steering wheel not shown in the diagram, the stub shaft 13
When the wormshaft 9 is rotated clockwise or counterclockwise, the wormshaft 9 connected to the stub shaft 13 via the torsion bar 17 also tries to rotate. Since the piston 1 and the wormshaft 9 are subject to ground resistance from the wheels via a control link (not shown), the piston 1 and the wormshaft 9 are immovable, and a torsion angle is created in the torsion bar 17 so that the wormshaft 9 and the stub shaft 13
That is, relative rotation occurs between the first plate 19 and the second plate 20, which are integral with each other. Then, for example, when the stub shaft 13 is rotated clockwise in FIG. The opening area of the oil passage 19d of the first plate 19 is gradually reduced at the hole edge of the oil passage 19d, and finally becomes zero, and the oil passage 9e communicates with the other working chamber 4.
The opening area for the oil passage 19e is increased, the hydraulic oil is sent to the working chamber 4, and the pressure in the working chamber 4 is increased. At the same time, the through hole 2 of the third plate 21
The oil passage 20d that communicates with the discharge hole 6 via 1a is
The opening area of the oil passage 19d of the first plate 19 where the oil passage 9d communicating with one of the working chambers 3 is opened is gradually increased at the hole edge of the oil passage 19d, and the hydraulic oil in the working chamber 3 is transferred to a tank (not shown). Drain. As a result,
The piston 1 is moved to the right to assist rotation of the sector shaft 5. The same thing happens when the stub shaft 13 is rotated counterclockwise, and this time the working chamber 3
Hydraulic oil is supplied inside and the piston 1 is moved to the left.
In this way, it is possible to effectively assist the wheel steering operation by rotating the steering wheel (not shown). Here, since the switching of the hydraulic oil to the working chambers 3 and 4 is carried out gradually as described above, the assisting action by the hydraulic oil gradually increases as the steering wheel turns, providing an extremely excellent steering feeling. A power steering device can be obtained. In addition, the plates 19 and 20 that provide oil passages for selectively supplying and discharging hydraulic oil can be press-formed from a thin steel plate or made of sintered material, so that the axial length can be shortened. As a result, a small and inexpensive power steering device can be obtained.

Furthermore, the rotational resistance of the bearings 11 and 12 that rotatably support the worm shaft 9 is due to the rotational resistance of the stub shaft 1.
Because it affects the rotational torque of the steering wheel through 3,
It is sensitively felt by the driver, and the size of each bearing 1
The magnitude of the rotational resistance varies depending on the magnitude of the axial force applied to the wheels 1 and 12, and it is undesirable for the steering sense that the magnitude of this rotational resistance changes, especially when the steering wheels are rotated clockwise or counterclockwise. The present invention can advantageously solve this problem. That is, the cross-sectional area of the wormshaft 9 facing the working chamber 3 is 1 ₁ , the cross-sectional area of the head 9a of the wormshaft 9 facing the mounting space 12a of the bearing 12 communicating with the working chamber 4 is a 2 , and the cross-sectional area of the head 9a of the wormshaft 9 facing the working chamber 4 is a ₂ , When the pressure per unit area is p, the wormshaft 9 receives a force of a ₁ ×p when the working chamber 3 is under high pressure,
When the working chamber 4 is under high pressure, it receives a force of (a ₂ −a ₁ )×p. Therefore, if we set the dimensions to the relationship a ₂ − _{a 1} , then
By selectively supplying and discharging hydraulic oil to the working chambers 3 and 4, the axial forces that the bearings 11 and 12 receive can be made equal. Furthermore, in response to the axial force, the wormshaft 9 receives a force due to the hydraulic pressure of the annular chamber 25 communicating with the supply hole 7 (this
By balancing the outer diameter of the plate 20 and the area of the oil passage 20c (which can be adjusted by appropriately selecting the outer diameter of the plate 20 and the area of the oil passage 20c), the axial force generated on the worm shaft 9 by the pressure of the hydraulic oil can be balanced and maintained. Therefore, no load is applied to the bearings 11 and 12, and the rotational resistance of these bearings 11 and 12 is reduced, allowing for nimble maneuvering.

Furthermore, when supplying hydraulic oil to each of the working chambers 3 and 4, the second plate 20 is connected to the oil passage 19d or 19e of the first plate 19, which communicates with the hydraulic oil supply hole 7. Depending on the area that is partially covered, it receives a force in the right direction in FIG. 1 and is pressed against the third plate 21. Since the third plate 21 is rotatably supported via the thrust bearing 22, even in such a case, the second plate 20 and the stub shaft 1 connecting it are
3 can be rotated smoothly, making the operation extremely smooth. Further, as described above, there is a relative gap between the second plate 20, the first plate 19, and the third plate 21 due to their rotation, although this is slight. However, due to this gap or due to the rotational gap between the drive pin 13b and the slot 20b, the second plate 20 rotates relative to the first plate 19, and the oil passage of the first plate 19 closes. When either 19d or 19e is throttled and the hydraulic oil flows, the second plate 20 in particular may generate slight vibrations. This vibration causes pulsation of the hydraulic oil, and as a result of the pulsation of the hydraulic oil vibrating the piston in the cylinder 2, it may generate abnormal noise or even vibrate the steering wheel (not shown), causing discomfort to the driver. However, in this case, as described above, the second plate 20 has a third plate having a seal ring 23 on its outer periphery.
It is pressed against the plate 21, and the second plate 2
0 rotates integrally with the third plate 21,
Vibration of the second plate 20 is effectively prevented by the sliding resistance of the seal ring 23 or by the damping effect due to elasticity.

Next, when the steering wheels are rotated when the ground resistance of the wheels is small, such as when the vehicle is running at high speed, the worm shaft 9 is easily rotated by the stub shaft 13 without causing a torsion angle in the torsion bar 17. It moves me. Therefore, there is no relative rotation between the first plate 19 and the second plate 20, and each working chamber 3, 4 is rotated in the same way as in the standard state described above.
No hydraulic pressure is generated. This means that the second plate 20 is not subjected to the aforementioned force in the right direction in the figure, so the second plate 20 can rotate with a slight distance from the third plate 21. , the seal ring 2 of the third plate 21
The sliding resistance 3 is not involved in the rotation of the second plate 20, and the rotation of the steered wheel becomes smooth.

Although an example has been described in which two sets of oil passages communicating with the working chambers 3 and 4 are provided in each of the worm shaft 9, the first plate 19, and the second plate 20, only one set each may be provided.

As explained above, according to the present invention, there is provided a wormshaft in which an oil passage is opened that communicates with each of the two working chambers, a stub shaft that engages with this wormshaft, and a stub shaft that communicates with each of the oil passages of the wormshaft. a first plate having a hole-shaped oil passage; a seal ring on the outer periphery that slides on the inner circumferential surface of the housing; the first plate is rotatably supported with respect to the housing; a third plate having a through hole, and a third plate located between the first plate and the third plate, directly supported by these plates, and rotatable integrally with a stub shaft connected to the steering wheel. ,
a second plate having an oil passage communicating with a hydraulic oil supply hole and a through hole of the third plate, and the relative rotation of the first plate and the second plate causes the first
By changing the opening area of each oil passage in the second plate relative to this oil passage at the hole edge of each oil passage in the plate, selective supply and discharge of hydraulic oil to the two working chambers was controlled. Produces the effects listed in.

(a) Wormshaft, first plate, and second
Since it is composed of the plate and the third plate, it is possible to obtain a power steering device with a small number of parts, a simple valve mechanism, a shortened axial length, and an inexpensive power steering device.

(b) Since the second plate is directly supported by the first plate and the third plate, the gap between each plate can be easily adjusted by changing the screwing amount of the rear cover 15.

(C) Since the third plate is rotatable with respect to the housing and is in sliding contact with the housing through the seal ring 23, the steering wheel can be smoothly rotated through the second plate, that is, the stub shaft, and the seal ring Vibrations of the entire valve mechanism caused by the flow of hydraulic oil can be effectively suppressed.

(d) Since the oil passage of the first plate is hole-shaped, machining is easy.

(e) Hydraulic oil supply and discharge is smooth, providing excellent handling sensation.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a power steering device showing an embodiment of the present invention, FIG. 2 is a sectional view taken along the - line in FIG. 1, and FIG. 3 is a sectional view taken along the - line in FIG. 1. 4 is a front view of the first plate, and FIG. 5 is a front view of the second plate. 1... Piston, 2... Cylinder, 3, 4...
Working chamber, 5... Sector shaft, 6... Housing, 7... Supply hole, 8... Discharge hole, 9... Wormshaft, 9c... Long groove, 9d, 9e... Oil path, 13... Stub shaft , 13a... flange, 19... first plate, 19d, 19e...
Oil passage, 20...Second plate, 20c, 20d...
...Oil passage, 21...Third plate, 21a...Through hole, 23...Seal ring.

Claims (1)

[Claims] 1. In a power steering device that selectively supplies and discharges hydraulic oil to two working chambers in a cylinder separated by a piston and assists rotation of a sector shaft connected to the piston, one end is screwed to the piston. a wormshaft, the other end of which faces into a housing that extends on the opposite side of the working chamber, and has at least one set of oil passages each communicating with the working chamber;
a first plate that is rotatable integrally with the wormshaft and has a hole-shaped oil passage communicating with each oil passage of the wormshaft; and a seal ring on the outer periphery that slides into contact with the inner peripheral surface of the housing;
and a third plate that is rotatably supported with respect to the housing and has a through hole communicating with the hydraulic oil discharge hole, and a third plate that is located between the first plate and the third plate and that is attached to each of these plates. A second plate that is directly supported, is rotatable together with a stub shaft connected to a steering wheel, and has at least one set of oil passages that communicate with the hydraulic oil supply hole and the through hole of the third plate, respectively. By the relative rotation of the first plate and the second plate, the opening area of the oil passage of the second plate relative to this oil passage is changed by the hole edge of the oil passage of the first plate, and the opening area of the oil passage of the second plate is changed. A power steering device characterized by controlling the supply and discharge of hydraulic oil to and from.