JPH01186469A - Power steering device - Google Patents

Abstract

PURPOSE:To prevent the one-sided abrasion on the edge surface of a piston by forming a recessed groove on the opposed edge surfaces of a pair of pistons, in the constitution in which the pistons are fitted in plural pairs of reacting power chambers, at the edge part of an output shaft connected through a torsion bar with a steering input shaft. CONSTITUTION:In the title device, a worm shaft 37 installed in a gear case 35 and stub shaft 38 on an input side are connected through a torsion bar 39, and the working oil supplied into a power cylinder is controlled by a control valve consisting of a rotary valve 40 and a sleeve 41 which is installed around the stub shaft 38. A large diameter part 42 is formed at the edge part of the worm shaft 37, and two pairs of reacting power chambers 43-46 are arranged oppositely. Though a pin 57 installed onto the stub shaft 38 is nipped between the opposed edge surfaces of the pistons 49-52 fitted in the respective reacting power chambers 43-46, a recessed groove 58 into which the pin 57 is fitted is formed on the opposed edge surfaces of the pistons 49-52.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a power steering device that selectively supplies pressure oil to a power cylinder via a control valve that is switched in response to input rotation of a steering wheel.

(Conventional Device) In the conventional device shown in FIGS. 6 and 7, a stub shaft 2 is inserted into the worm shaft 1, and both shafts are connected by a torsion bar 3. Further, both ends of the pin 4 connecting the stub shaft 2 and the torsion bar 3 are made to protrude to the outside of the stub shaft 2. As is clear from FIG. 7, both ends of the pin 4 projecting outward from the stub shaft 2 are connected to reaction chambers 6, 7, 8, and 9 formed in the large diameter portion 5 of the worm shaft 1. It's coming in between.

The reaction force chambers 6 and 7 and the reaction force chambers 8 and 9 are arranged in series in a direction perpendicular to the axis of the warm shirt l, and the reaction force chambers 6 and 7 and the reaction force chambers 8 and 9 are Protrusion 1 between
0.11.

Further, a collar 12 is provided around the large diameter portion 5 to close the outward openings of the reaction force chambers 6 to 9, and press pistons 13 to 18 are housed in the reaction force chambers 6 to 9. Compression springs 17 to 20 are interposed between the pressing pistons 13 to 18 and the collar 12, and normally the pressing pistons are brought into pressure contact with the protrusion 1O111.

Therefore, as mentioned above, reaction force chambers 6 and 7, reaction force chambers 8 and 9
The pin 4 facing between the press pistons 13 to 1B
Normally, it is held at the neutral position shown in the figure.

The collar 12 has oil holes 22 to 25 that communicate the reaction chambers with the pump port 21, and a passage 27 formed in the valve housing 26, which communicates the reaction chambers with the drain chamber 28. Drain ports 28 to 32 are formed.

A variable throttle 33 is provided in the passage 27, and the opening degree of the variable throttle 33 is adjusted in accordance with the speed of the vehicle. In other words, the opening degree of the variable diaphragm 33 increases when the vehicle is traveling at low speeds, and decreases when the vehicle is traveling at high speeds.

Now, if the handle is rotated to rotate the pin 4 clockwise in FIG. 7, the diagonally located suppression pistons 14 and 15 move against the compression springs 18 and 19. When the piston 14.15 moves in this manner, the oil in its reaction chamber 7.8 is forced out of the drain port 30.31 and flows into the drain chamber 28 via the variable throttle 33.

At this time, if the vehicle is running at a low speed, the opening degree of the variable throttle 33 is large, so that the throttle resistance is almost eliminated. For this purpose, the handle can be rotated slightly. On the other hand, when driving at high speed, the opening degree of the variable throttle 33 becomes smaller and the throttle resistance increases accordingly.
The pressure in the reaction chamber 7.8 increases, which acts as a reaction force against the rotational force of the stub shaft 2. Since the stub shaft 2 is connected to the steering wheel, the pressure in the reaction force chamber is ultimately transmitted to the steering wheel as a steering reaction force.

Note that by rotating the stub shaft 2, the control valve 34 is switched, and the steering direction is controlled according to the switching position.

(Problems to be Solved by the Present Invention) In the conventional power steering device as described above, the pin 4 having a circular cross section is brought into contact with the end face of the suppression pistons 13 to IB. will come into line contact, and the pressing force will be concentrated on that contact area. Therefore, there was a problem in that the end surfaces of the pressing pistons 13 to 16 were unevenly worn.

Furthermore, as the device becomes larger, the steering reaction force must also be increased, and in this case, the diameter of the pressing piston is increased. When the diameter of the piston is increased in this way, unless the length is also increased, the pressing piston will tilt during the sliding process. However, this conventional device has a problem in that the pressing piston cannot be made longer unless the length of the reaction chambers 6 to 9 is increased.

An object of the present invention is to provide a device that prevents uneven wear of a piston provided in a reaction chamber and that allows the length of the suppression piston to be increased while maintaining the pressure chamber as before.

(Means for Solving Problems) This invention has a piston internally installed in a gear case provided with a valve housing on the minus side, and a worm shaft whose one end is engaged with the piston, and a stub shaft rotatably attached to the other end of the worm shaft. The worm shaft and stub shaft are connected by a torsion bar. The valve housing is provided with a control valve for guiding pressure oil from a hydraulic source to either the left or right side of the piston, and the control valve is configured to be switched in accordance with rotation of the handle. Moreover, the stub shaft is provided with a pin in a direction perpendicular to its axis, a plurality of reaction force chambers are formed on the other end side of the worm shaft, a pressing piston is housed in the reaction force chamber, and the pin It is configured to be located between mutually opposing pressing pistons, and a concave groove into which a pin provided on the stub shaft fits is formed on the opposing side surface of the pressing piston.

(Operation of the present invention) Since the present invention is configured as described above, by rotating the stub shaft and switching the control valve, the steering direction can be controlled according to the switching position. Moreover,
At this time, a steering reaction force is exerted due to the reaction force action of the reaction force chamber.

(Effects of the Invention) According to the power steering device of the present invention, a concave groove is formed in the end surface of the suppression piston that contacts the pin provided on the stub shaft, and the pressing piston and the pin are brought into surface contact within the concave groove. This makes it possible to prevent uneven wear due to contact between the two.

In addition, since the pin is inserted into the groove, the length of the pressing piston that can accommodate the pin inserted can be increased. Therefore, even if the diameter of the pressing piston is increased in order to obtain a large steering reaction force, the length of the pressing piston can be made sufficiently long accordingly, and the piston will not tilt during the sliding process.

(Embodiment of the present invention) The embodiment of the present invention shown in Figs.
A valve housing 36 is provided on one side of the gear case 5, and a piston (not shown) is housed inside the gear case 35. In addition, a worm shaft 37 provided in this gear case 35
and a stub shaft 38 rotatably supported by the valve housing 36 are connected via a torsion bar 39.

The stub shaft 38 is provided with a rotary valve 40 that rotates integrally with the stub shaft 38, and a rotary sleeve 41 is fitted around the outer periphery of the rotary valve 40. Note that this rotary valve 40 and rotary sleeve 41 constitute a control valve of the present invention.

Further, a large diameter portion 42 is formed on the stub shaft side of the worm shaft 37, and this large diameter portion 4
The rotary sleeve 41 is fitted onto the outer periphery of 2.

In the large diameter portion 42 as described above, reaction force chambers 43, 44, 45, and 46 are formed as in the conventional case. The reaction force chambers 43 and 44 and the reaction force chambers 45 and 46 are arranged in series in a direction perpendicular to the axis of the worm shaft 37, and the reaction force chambers 43 and 44 and the reaction force chambers 45 and 46 are Stoppers 47 and 48 are projected between them.

Further, the reaction force chambers 43 to 46 are provided with pressing pistons 48 to 48.
52 inside. Compression springs 53 to 5 are provided between the pressing pistons 48 to 52 and the valve sleeve 41.
6 is interposed, and normally the above-mentioned suppression piston is brought into pressure contact with the stopper 47, 48.

A pin 57 passed through the stub shaft 38
facing between the reaction force chambers 43 and 44 and the reaction force chambers 45 and 46, and this pin 57 and the stoppers 47 and 48
I am trying to match the axes of the

As shown in FIG. 1, each of the suppressing pistons 49 to 52 as described above has a groove 58 on the side in contact with the pin 57, which has the same radius of curvature as the outer periphery of the pin 57 and the stopper 47, 48. is forming. Therefore, when the pressing pistons 48 to 52 are in the illustrated neutral position under the action of the compression springs 53 to 56, the en 57 and the par 47, 48 fit into the groove 58. Since the concave grooves 58 are formed in the end surfaces of the pressing pistons 49 to 52 in this way, as shown in FIG.
52 can be made as long as the depth of the groove 58.

In addition, in each of the reaction force chambers 43 to 46, the reaction force chamber located on one of the diagonals communicates with the tank depending on the switching position of the control valve, and the control thereof is the same as in the conventional case. It is.

However, in this embodiment, the valve housing 36
The variable orifice control valve V inputs the vehicle speed signal detected by the vehicle speed sensor 58 to the solenoid 60 via the controller C, and adjusts the pressure in the reaction force chamber according to the vehicle speed. I'm trying to control it.

The entire circuit diagram including the variable orifice control valve V is shown in FIG. That is, the hydraulic source 61 is connected to the actuator 62, and this hydraulic source 61
is communicated with the tank T via the first variable orifice v1 and the second variable orifice (2), and the two variable orifices v1, (2) are connected to the reaction chambers 43-46.

While the vehicle is running at high speed, the opening degree of the first variable orifice v1 is maximized and the opening degree of the second variable orifice v2 is minimized. In this way, the pressure within the reaction force chambers 43 to 48 is maintained at the highest level, and the steering reaction force is maximized.

On the other hand, when the vehicle is running at low speed, the first variable orifice v1 is almost closed and the second variable orifice v2 is maximally opened. In this way, the pressure in the reaction force chambers 43 to 46 can be reduced to almost zero, thereby minimizing the steering reaction force.

By controlling the opening degrees of both variable orifices vl and v2 in this manner, the steering reaction force can be freely adjusted.

In this embodiment, the upstream orifice v1 is a variable orifice, so for example, during low-speed running when pressure in the reaction chambers 43 to 48 is not required, this variable orifice
1 is fully closed, and all the oil supplied from the hydraulic source 61 can be supplied to the actuator 62.

According to this embodiment as described above, the pressing piston 4
Since the concave grooves 58 are formed on the end faces of pistons 8 to 52, the piston comes into surface contact with the pin 57, and uneven wear of the piston end faces can be prevented accordingly. In addition, this groove 5
Since the piston can be lengthened by the depth of 8, the piston becomes more stable and will not tilt during the sliding process.

[Brief explanation of the drawing]

Drawings 1 to 5 show embodiments of this invention.
The figure is a perspective view of the pressing piston, Figure 2 is a sectional view of the main part, Figure 3 is a sectional view taken along the line ■-■ in Figure 2, and Figure 4 is the IV in Figure 3.
-IV line sectional view, Figure 5 is a circuit diagram, Figure 6.7 shows a conventional device, Figure 6 is a sectional view of the main part, and Figure 7 is a cross section taken along the ■-■ line in Figure 6. It is a diagram. 35... Gear case, 36... Valve housing,
37... Worm shaft, 38... Stub shaft, 38... Torsion bar, 40 and 41... Rotary valve and rotary sleeve constituting the control valve, 43-46... Reaction force chamber, 48- 52...Press piston, 57...Bin, 58...Concave groove, 61...
Hydraulic source.

Claims (1)

[Claims] A valve housing is provided on one side of the gear case, a piston is housed inside the gear case, and a stub shaft is fitted to the other end of a worm shaft whose one end is engaged with the piston, allowing relative rotation. and the stub shaft are connected by a torsion bar, and the valve housing is provided with a control valve for guiding pressure oil from a hydraulic source to either the left or right side of the piston. The stub shaft is provided with a pin in a direction perpendicular to its axis, a plurality of reaction force chambers are formed on the other end of the worm shaft, and a pressing piston is installed in the reaction force chamber. The power steering device is configured such that the pin is located between mutually opposing pressing pistons, wherein a concave groove into which a pin provided on the stub shaft fits is formed on a side surface facing the pressing piston. .