JPH03200477A - Integral-type power steering - Google Patents

Abstract

PURPOSE:To improve steering stability during high speed running by providing reaction mechanism between a stub axle and a worm shaft rotated by a steering wheel in an integral-type power steering. CONSTITUTION:A piston 6 is slidably fitted into a cylinder 4 in a gear housing 2, and a sector gear 14 interlockingly connected to a steering wheel is meshed with a rack 12 formed at the side face of the piston 6. A ball thread groove 18 is formed in the hole 16 of the axial part of the piston 6, and a worm shaft 20 is screwingly fitted thereto through numerous balls 19. A stub axle 26, disposed in a valve housing 22 connected to one end of the gear housing 2, is connected to the worm shaft 20 by a torsion bar 30. In this case, a reaction plunger 56 is fitted into a hole 54 formed at the worm shaft 20 so as to provide reaction mechanism 51 formed by engaging the reaction plunger 56 with an engaging part 52 formed at the stub axle 26.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power steering device, and particularly to an integral type power steering device.

[Conventional technology]

The integral type power steering device has a piston fitted in a cylinder provided in a gear housing so as to be able to reciprocate.
A sector gear that interlocks with the steering wheels is engaged with the rack formed on this piston, and a worm shaft (output shaft) is screwed into the piston via a ball screw, and a stub shaft that is rotated by the steering handle. (input shaft)
The two shafts are arranged on the same axis and connected by a torsion bar, and the oil path is switched by a control valve consisting of a valve member provided on each shaft to operate the piston and assist the steering force. It has become.

This power steering device is provided with a reaction force mechanism that applies hydraulic pressure to a reaction force chamber to generate a steering reaction force in order to allow a driver to sense steering resistance. This reaction mechanism is usually
The reaction force is generated according to the speed of the vehicle, and is light when the vehicle is stopped or running at low speeds, and relatively heavy when the vehicle is running at high speeds, providing a stable steering feel.

It has been known that the above-mentioned integral type power steering device is provided with such a reaction force mechanism (Japanese Patent Publication No. 48-1
No. 4743).

[Problem to be solved by the invention]

In the above-mentioned conventional integral type power steering system, the control valve is constructed by connecting cylindrical valve members to the stub shaft and the worm shaft through bottles, and the reaction force mechanism is provided between these two valve members. ing. As described above, there is a strength problem due to the force f pin connection of the reaction force mechanism, and there is also a limit to the size of the reaction force chamber due to the reaction force mechanism being located on the outer periphery of the control valve. There were cases where the steering reaction force could not be obtained.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide an integral type power steering device that does not have problems in terms of strength and has a reaction force chamber of sufficient size.

(Means for Solving the Problems) An integral type power steering device according to the present invention includes a stub shaft rotated by a steering handle, a worm shaft disposed on the same axis as the stub shaft, and a worm shaft arranged on the same axis as the stub shaft. A control valve consisting of a valve member that is rotatably provided with the shaft, a piston that is fitted to the worm shaft via a ball screw and reciprocates within a cylinder provided in the gear housing, and a control valve formed on the piston. The worm shaft is provided with a sector gear that engages with the stub shaft and rotates with the reciprocation of the piston.In particular, a reaction plunger is slidably fitted into the hole formed in the worm shaft, and The reaction force plunger is engaged with the formed engagement portion, and the hydraulic pressure discharged from the oil pump is applied to the back side of the reaction force plunger.

[Effect]

In the integral power steering device according to the present invention, when the stub shaft is rotated by the steering handle and a relative rotational displacement occurs between the stub shaft and the worm shaft, the reaction force is pushed by the engaging portion of the stub shaft and retreated. The hydraulic pressure acting on the back side of the plunger acts to push both shafts back to the neutral position, and this force is transmitted to the steering wheel as a steering reaction force.

〔Example〕

The present invention will be explained below with reference to illustrated embodiments. FIG. 1 is a longitudinal cross-sectional view of an integral type power steering device according to an embodiment of the present invention, in which a piston (6) is slidably disposed within a cylinder portion (4) within a gear housing (2). is mated to
The inside of the cylinder (4) is divided into two pressure chambers (8) and (10) by this piston (6). A rack (1
2) is formed, and a sector gear (14) that is interlocked with a steering wheel (not shown) is meshed with this rack (12), so that it rotates forward and backward as the piston (6) reciprocates. ing.

A ball screw groove (18) is screwed into the hole (16) in the axial center of the piston (6), and the worm shaft (output shaft) (20 ) are screwed together. A cylindrical portion (22a) of a valve housing (22) is fitted into one end of the gear housing (2),
It is fixed with bolts (24). A stub shaft (input shaft) (26) is disposed within the valve housing (22) with its axis aligned with the worm shaft (2o). A large-diameter cylindrical portion (20a) is formed at the end of the worm shaft (20) on the stub shaft (26) side.
0a), the tip of the stub shaft (26) is inside the bearing (
28). Both of these axes (20).

(26) are connected by a torsion bar (30) inserted into the hole at their axis. In addition, the inner surface of the worm shaft (20) and the outer surface of the stub shaft (26) are provided with fail-locks to allow a predetermined amount of relative rotation between the two shafts (20) and (28), and to restrict further rotation. A safe (32) is formed. Note that the stub shaft (2
6) is connected to a steering wheel (not shown) and rotated.

A valve rotor (inner valve member) (34) is formed directly on the outer peripheral surface of the central portion of the stub shaft (26), and a valve sleeve (outer valve member) (38) is fitted around the outer periphery of the valve rotor (34). This valve sleeve (36) is inserted into the worm shaft (
20) so that they rotate integrally.
These valve rotor (34) and valve sleeve (36) constitute a rotary type control valve (40).

The control valve (40) has a valve housing (2
It communicates with the oil pump through a supply port (42) formed in 2) and with the tank through a return port (44), and this control valve (40) is switched and operated by operating the steering handle. Then, the pressure oil discharged from the oil pump is supplied to the pressure chambers (8) and (10), and the other pressure chamber is communicated with the tank, creating a pressure difference between the compartments. Piston due to pressure difference ([1)
is activated to apply assisting force in the steering direction.

The stub shaft (
26) The side end fits into the outer periphery of the valve sleeve (36), and the ohmic shaft (20) and the stub shaft (26)
The inner race (
46a). This ball bearing (46
) is the outer race (46b) of the worm shaft (20).
It is held at the bottom of the valve housing (22) by an adjusting plug (50) inserted between the outer peripheral surface of the cylindrical part (20a) of the valve housing (22) and the cylindrical part (22a) of the valve housing (22) and fixed by a screw (48). has been done.

A reaction force mechanism (51) is provided near the cylinder at the part where the worm shaft (20) and the stub shaft (26) are fitted, and this reaction force mechanism (51) is shown in FIGS. 1 and 2. This will be explained in detail with reference to the drawings. Two protrusions (52) are formed at symmetrical positions on the outer circumference of the stub shaft (26), and holes (54) are formed in the worm shaft (20) from a direction perpendicular to both sides of these two protrusions (52). ) are formed, and a reaction force plunger (56) is slidably and tightly fitted into each of these base holes (54).

The reaction force mechanism (5) of the adjusting plug (50)
1) There is an annular groove (50a) on the inner surface of the part located around the
is formed, and seal members (58) are attached to both sides of this annular groove (50a). In addition, this seal member (5
An O-ring may be attached to the outer periphery of 8). Furthermore, an annular space (60) is formed between the outer circumferential surface of the adjusting plug (50) and the inner circumferential surface of the valve housing (22). A ring (62) is attached. Furthermore, an annular groove (
22b) is formed, and 0 on both sides of this annular groove (22b).
A ring (64) is attached.

The annular groove (22b) also has a gear housing (22b).
Pressure oil from a hydraulic source is introduced through an inlet (not shown) formed in ).

The valve housing (22) has a passage hole (22c) that communicates the outer annular groove (22b) of the valve housing with the inner annular space (60). , the annular space (60) and the annular groove (50a) on the inner peripheral side of the adjusting plug (50).
) is provided with a passage hole (50b) that communicates with the two.

Therefore, the annular groove (22b) of the valve housing (22)
The pressure oil introduced into the passage hole (22c) and the annular space (
60), is introduced into the back side of the reaction force plunger (56) via the passage hole (50b) and the annular groove (50a). Note that the hydraulic pressure source may be a pump common to the power steering device, or may be a separate sub-pump whose discharge amount increases or decreases depending on the vehicle speed.

Next, the operation of the power steering device having the above configuration will be explained. When the stub shaft (26) is rotated by operating the steering handle, the stub shaft (26) and the worm shaft (20
), which causes a relative rotational displacement between the valve rotor (34) formed on the stub shaft (26) and the worm shaft (
A relative rotational displacement also occurs between the valve sleeve (36) connected to the control valve (40), and the flow path in the control valve (40) is switched, and the two pressure chambers (8L) in the cylinder (4)
One of the pistons (10) communicates with the oil pump and the other communicates with the tank, and the piston (6) moves, thereby operating as a power steering device.

When the stub shaft (26) and the worm shaft (20) rotate relative to each other as described above, the protrusion (52) of the stub shaft (26) constituting the civil power mechanism (51) moves into the reaction force plunger facing on both sides. Press one side of (56) to move it backward. On the back side of each reaction plunger (56), pressure oil discharged from the oil pump whose discharge amount increases as the vehicle speed increases, is formed in an annular groove (22b), a passage hole (22c), an annular space ( 60), passage hole (50b) and annular groove (5
0a), the reaction force plunger (56) is pushed and retreated by the hydraulic pressure.
A rotational force is applied to push the protrusion (52) of the stub shaft (26) back to the neutral position (the state shown in FIG. 2). This rotational force is transmitted to the steering wheel as a steering reaction force, making it possible to improve steering stability during high-speed travel.

In this example device, the stub shaft (26) and the ohm shaft (2
Since the reaction force mechanism (51) is provided between the worm shaft (20) and the reaction force plunger (62), there is no problem in terms of strength. Since it is provided, it is possible to enlarge this reaction force chamber,
The degree of freedom in setting the steering force under each driving condition can be increased. Furthermore, by forming the annular groove (22b) on the outer periphery of the valve housing (22), hydraulic pressure can be introduced from all over the circumference. Furthermore, with the above configuration, the basic structure can be the same as that of an integral type power steering device that does not have a reaction force mechanism, and there is no disadvantage of providing a reaction force mechanism, and there is no risk of increasing the size.

3 and 4 show a second embodiment, which is the same as the above embodiment except for the configuration of the reaction force mechanism (151), so the same parts are given the same reference numerals and explained. omitted. In this embodiment, an annular large diameter portion (102) is formed on the outer periphery of the stub shaft (26), and four recesses (104) are provided in this large diameter portion (102) at equal intervals in the circumferential direction. There is. These recesses (104) consist of two inclined surfaces. On the other hand, the large diameter portion (20a) of the worm shaft (20) has four holes (10
6) is formed, and a reaction force plunger (110) is provided with a ball (108) in each of these through holes (10B).
) are slidably and tightly fitted. Hydraulic pressure is applied to the back side of each of these reaction force plungers (110) in the same manner as in the above embodiment.

In the device of this embodiment, the stub shaft (26) and the worm shaft (2
0) rotates relatively, the center of each ball (108) shifts from the center of each recess (104), and the recess (104)
is pushed up by the slope of the Similar to the above embodiment, the hydraulic pressure acting on the back surface of the reaction force plunger (110) exerts a force that causes the ball (108) to push the inclined surface of the recess (104) and return it to the neutral position, and this force acts as a steering reaction force. is transmitted to the handle as follows. It goes without saying that this power steering device can also provide the same effects as the above embodiment.

〔Effect of the invention〕

As described above, according to the present invention, by providing a reaction force mechanism between the stub shaft and the worm shaft of the integral type power steering device, steering stability during high-speed running can be improved. Furthermore, a reaction force mechanism with high strength can be obtained, and an increase in size can be avoided.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an integral type power steering device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a reaction force mechanism, and FIG.
1 and 4 correspond to FIG. 1 and FIG. 2 of the second embodiment, respectively. (2) Gear housing (4) Cylinder (6) Piston (12) Rack (14) Sector gear (20) Worm shaft (26) Stub shaft (34), (36)...Valve member (40)...Control valve (52)...Stub shaft engaging portion (54)...Worm shaft hole (56)... reaction plunger

Claims (1)

[Claims] A stub shaft rotated by a steering handle, a worm shaft disposed on the same axis as the stub shaft, a control valve consisting of a valve member provided so as to be rotatable integrally with each of these shafts, and a control valve on the worm shaft. An integral gear that includes a piston that is fitted via a ball screw and reciprocates within a cylinder provided in a gear housing, and a sector gear that engages with a rack formed on the piston and rotates as the piston reciprocates. In the type power steering device, a reaction force plunger is slidably fitted into a hole formed in the worm shaft, and the reaction force plunger is engaged with an engagement portion formed on the outer periphery of the stub shaft, and the reaction force plunger is slidably fitted into a hole formed in the worm shaft. An integral power steering device characterized by applying discharge hydraulic pressure from a hydraulic source to the back side of a force plunger.