JPS6231672B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in power steering devices for vehicles such as automobiles.

Conventionally, power steering devices have been used to assist in transmitting steering force from the steering wheel to the tires.
Therefore, the input shaft and output shaft that receive the steering force from the handle are connected by a torsion bar, and a valve spool provided coaxially with the input shaft is moved in the axial direction according to the rotation direction of the input shaft to switch the hydraulic pressure. is configured to do so.

In such conventional power steering devices, a spiral ball groove is formed on the input shaft to convert the rotation of the input shaft into axial movement of the valve spool, and a ball slides along the ball groove. A transmission mechanism consisting of balls is used. However, in conventional devices, the ball holder for holding the ball is separate from the valve spool, and the ball holder rotates and moves in the axial direction, while the valve spool is prevented from rotating. It is limited to movement only in the axial direction. Furthermore, among conventional power steering devices, there is a technology in which the ball holder part and the valve spool are integrated (Japanese Patent Application Laid-open No. 47-36341), but in this technology, the spiral ball The groove is formed in a member called the valve actuator ring that exists outside the valve spool, so the ball must work while contacting the three members: the input shaft, the valve spool, and the valve actuator ring.

Therefore, in order for the device to operate smoothly, 3
The two parts must be maintained in precise alignment at all times. As a result, there are a large number of parts, and strict precision is required between the parts, which makes assembly difficult. In addition, vibration or surging of the valve spool occurs, which has an unfavorable effect on hydraulic switching characteristics. Ta.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power steering device that eliminates the drawbacks of the prior art, has a small number of parts, and can prevent surging.

To achieve this object, the power steering device according to the present invention has an input shaft and an output shaft that are rotatably mounted on a common axis in a valve housing, and are connected via a torsion bar. A valve spool is arranged concentrically around the periphery of the valve spool and is movable in the axial direction. The valve spools are coupled so as not to rotate relative to each other, and the first orbit is twisted at a certain angle with respect to the axial direction of the input shaft, and when the input shaft and the output shaft rotate relative to each other, The valve spool is characterized in that it moves in the axial direction to switch the oil passage, and that the valve spool has a dynamic damper mechanism for preventing surging.

The present invention will be further described below with reference to embodiments shown in the drawings.

FIG. 1 is a sectional view showing an embodiment of a power steering device according to the present invention. As is clear from FIG. 1, the input shaft 2 inserted into the valve housing 1 receives the steering force from the handle at its serrations on the outer diameter side, and the input shaft 2 is connected to the output shaft inside the rack housing 3. Torsion bar 5 for 4
are connected to each other so as to be relatively rotatable in the same direction. Therefore, the input shaft 2 and the torsion bar 5 are connected by a pin 6, and the torsion bar 5
and the output shaft 4 are connected by a pin 7. A needle bearing 8 is provided on the outer circumferential side of the input shaft 4, while a ball bearing 9 is provided on the outer circumferential side of the output shaft 4.

A spiral ball groove 10 (first track) twisted at a certain angle with respect to the axial direction of the input shaft 2 is formed near the end of the input shaft 2 on the output shaft 4 side.

A valve spool 11 is provided between the outer circumferential side of the input shaft 2 and the inner circumferential side of the valve housing 1 for switching the hydraulic pressure in cooperation with an oil groove provided on the inner circumferential side of the valve housing 1. is the input shaft 2
It is provided coaxially and movably in the axial direction. This valve spool 11 has an oil groove 12 that is switchably communicated with the oil groove on the inner circumference of the valve housing 1 at the upper end side of the figure, and has two oil grooves 12 on diametrically opposite sides near the lower end of the valve spool 11. is provided with a circular ball holding hole 13, and the lower end of the valve spool 11, that is, the output shaft 4
Stopper grooves (second raceways) 14 are formed at two locations on opposite sides in the diametrical direction of the side ends.

A ball 15 that engages with the ball groove 10 of the input shaft 2 and is slidable along the ball groove 10 is housed in the ball holding hole 13, and the ball 15 has a ball 15 on the outer periphery thereof. A ball retainer 16 is provided to hold the balls 15 on the inner diameter side. A dynamic damper mechanism is provided on the outer periphery of the upper end of the ball retainer 16 to form an oil reservoir space 18 for preventing surging between the inner periphery of the valve housing 1 and a part of the outer periphery of the valve spool 11. A damper portion 17 is integrally formed in the shape of an upright flange. The outer peripheral surface of this damper portion 17 is the valve housing 1
The valve spool 11 is configured to function as a so-called dynamic damper that provides resistance when the valve spool 11 moves rapidly. There is.

A pin 19 extending radially from the end of the output shaft 4 on the input shaft 2 side engages with the stopper groove 14 of the valve spool 11, and the pin 19 causes the valve spool 11 to rotate relative to the input shaft 2. It prevents you from doing so.

The valve housing 1 includes a pressure port 25 for supplying hydraulic pressure from a hydraulic pump, a return port 26 for returning hydraulic pressure to the reservoir, and an arrow 2.
As shown at 7 and 28, cylinder ports are formed which communicate with the left cylinder chamber and the right cylinder chamber.

Next, the hydraulic pressure switching operation according to this embodiment will be explained. First, the state in which the valve spool 11 is at the neutral point is as shown in FIG. 2, and from this state in FIG.
When the input shaft 2 is twisted to the left, as shown in FIG. 3, the ball groove 10 formed in the input shaft 2 rotates to the right (counterclockwise) in the figure as indicated by the arrow. In this case, the ball 15 engaged with the ball groove 10 slides downward in the axial direction along the ball groove 10 as shown by the arrow, since the valve spool 11 is restrained by the pin 19 so that it cannot rotate. As a result, the valve spool 11 cooperates with the oil groove provided on the inner periphery of the valve housing 1 to switch the oil pressure.

That is, during actual steering, the input shaft 2
When the output shaft 4 also rotates with respect to the rotation angle θ ₁ , and the angle is θ ₂ , the valve spool 11 moves in the axial direction according to the difference angle (torsion angle) between θ ₁ - θ ₂ . This is used to switch hydraulic pressure.

When the valve spool 11 moves in the axial direction as described above, the damper portion 17 provided on the outer circumferential side of the ball retainer 16 prevents oil from flowing between the inner circumference of the valve housing 1 and a part of the outer circumference of the valve spool 11. Since a reservoir space 18 is formed, the oil trapped in this oil reservoir space 18 cannot suddenly escape from the oil reservoir space 18 when the valve spool 11 moves rapidly, Since the oil cannot enter the valve spool 11 suddenly, and the oil enters and exits slowly over a period of time, it acts as a so-called dynamic damper to resist rapid operation. surging can be prevented. That is, when oil flows in and out through the clearance formed between the outer circumferential surface of the damper portion 17 and the inner circumferential surface of the valve housing 1, resistance is generated to the rapid movement of the valve spool due to the viscous resistance of the oil.
The vibration movement of the valve spool due to surging is rapid and minute. Therefore, even the amount of oil trapped in the oil sump space that enters and exits through minute clearances can act as a resistance to the caging. Of course, the damper section 17 can function to prevent surging of the valve spool 11 even when the valve spool 11 is not in operation.

FIG. 4 is a partial sectional view showing another embodiment of the power steering device according to the present invention. In this embodiment, the damper section 17 on the outer circumferential side of the ball retainer 16 and the oil reservoir space 18 formed by the damper section 17 are omitted, and the hole formed in the end surface of the valve spool 11 on the output shaft 4 side is omitted. , a pin 20 is attached as shown in FIG. 5, and this pin 20 is configured to fit into a pin hole 22 of a damper member 21 fixed to the outer peripheral side of the output shaft 4 so as to face the pin 20. There is. The damper member 21 having the pin 20 and the pin hole 22 functions as a dynamic damper mechanism, and the output shaft 4
It also functions as a rotation prevention mechanism for the valve spool 11. Therefore, in this embodiment, the stopper groove 14 and the pin 19 that engages with the stopper groove 14 in the previous embodiment are omitted.

In the case of this embodiment, the pin hole 22 also functions as an oil reservoir space. That is, as in the first embodiment (FIG. 1), the oil in the oil reservoir space is absorbed by the pin 20 due to the rapid movement of the valve spool 11.
and the pin hole 22, causing resistance. Therefore, in this embodiment as well, it is possible to fully exhibit the dynamic damper effect on the valve spool 11, and surging of the valve spool 11 can be effectively prevented. It should be noted that, contrary to this embodiment, a case where a pin hole is provided on the end surface of the input shaft 2 on the output shaft 4 side and a pin 20 is provided on the opposing surface on the damper member 21 side is also included in the present invention.

FIG. 6 shows yet another embodiment according to the present invention. In this embodiment, protruding teeth 23 protruding in the axial direction are formed on the end surface of the valve spool 11 on the output shaft 4 side at two locations on the opposite side in the diametrical direction, and the damper member 2 facing these protruding teeth 23
1 is formed with a recess 24 that can fit into both protruding teeth 23 and each other. Also in the case of this embodiment, the protruding teeth 23
The recess 24 functions as a dynamic damper mechanism, and the recess 24 functions as an oil reservoir. That is, as in the first embodiment (FIG. 1), the oil in the oil reservoir space moves in and out through between the protruding teeth 23 and the recess 24, creating resistance to the rapid movement of the valve spool 11. Therefore, in this embodiment as well, surging of the valve spool 11 can be effectively prevented. In addition, also in the case of this embodiment, the protruding teeth 23 are formed on the side of the damper member 21,
A recess that fits into the protrusion may be formed on the end surface of the valve spool 11 on the output shaft 4 side, and such a case is also included in the present invention.

In the above embodiment, the volume of the oil reservoir changes with the movement of the valve spool in the axial direction, and by delaying the inflow and outflow of oil in response to this change in volume, it acts as a damper mechanism. .

As explained above, according to the present invention, it is possible to prevent surging of the valve spool, and the number of parts is small, making it possible to easily perform production and assembly. It will be done.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the power steering device according to the present invention, FIGS. 2 and 3 are partial sectional views for explaining the operation of the embodiment shown in FIG. 1, and FIG. FIG. 5 is a partial perspective view showing an enlarged view of the dynamic damper mechanism shown in FIG. 4; FIG. 6 is a partial sectional view showing another embodiment of the present invention; FIG. 6 is a partial perspective view showing another embodiment of the present invention. FIG. 3 is an enlarged perspective view of the dynamic damper mechanism. 1...Valve housing, 2...Input shaft, 4...
... Output shaft, 5 ... Torsion bar, 10 ... Ball groove, 11 ... Valve spool, 14 ... Stopper groove, 15 ... Ball, 16 ... Ball retainer, 17 ... Damper section, 18 ... Oil sump space ,1
9, 20...pin, 21...damper member, 22...
...pin hole, 23...protrusion, 24...recess.

Claims (1)

[Scope of Claims] 1. An input shaft and an output shaft, which are rotatably arranged on a common axis within a valve housing, are connected via a torsion bar and are arranged concentrically around the input shaft, The valve spool, which is formed to be freely movable in the axial direction, engages with a ball formed on the input shaft and placed on a first orbit, and further, the output shaft and the valve spool cannot move relative to each other in the axial direction. The first orbit is twisted at a certain angle with respect to the axial direction of the input shaft, and when the input shaft and the output shaft rotate relative to each other, the valve spool is restrained from relative rotation. A power steering device, characterized in that the valve spool switches an oil path by moving in an axial direction, and the valve spool has a damper mechanism for preventing surging. 2. The output shaft has a radially extending pin that engages with a second track formed in the valve spool, and the damper mechanism is provided on the outer periphery of a ball retainer that holds the balls from the outer periphery side. is,
The power steering device according to claim 1, further comprising a damper portion that forms an oil reservoir space between the valve spool and the valve housing. 3. Claim 1, wherein the damper mechanism comprises a pin provided in the axial direction of the output shaft side end surface of the valve spool, and a damper member that engages with the pin and functions as an oil reservoir space. The power steering device described. 4. The damper mechanism includes protruding teeth integrally formed in the axial direction of the output shaft side end surface of the valve spool;
The power steering device according to claim 1, further comprising a damper member having a recessed portion that engages with the protruding teeth and serves as an oil reservoir space.