JP2521978Y2 - Integral type power steering device - Google Patents

Description

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

[Conventional technology]

The integral type power steering device is configured such that a piston is reciprocally fitted in a cylinder provided in a gear housing, and a rack formed on the piston is meshed with a sector gear interlocking with a steering wheel, and a piston inside the piston is formed. Worm shaft (output shaft) screwed into the ball screw
And a stub shaft (input shaft) rotationally operated by a steering handle are arranged on the same axis, and both shafts are connected by a torsion bar, and a control valve comprising a pair of valve members provided on both shafts, respectively. The oil passage is switched to operate the piston to assist the steering force.

This power steering device is provided with a reaction force mechanism that generates a steering reaction force by applying a hydraulic pressure to a reaction force chamber in order to make a driver sense steering resistance. This reaction force mechanism normally generates a reaction force according to the traveling speed of the vehicle, and is light when the vehicle is stopped or traveling at a low speed, and relatively heavy when traveling at a high speed so that a stable steering feeling can be obtained. I have to.

Conventionally, as an integral type power steering device provided with this kind of reaction force mechanism, for example, those shown in Japanese Utility Model Laid-Open No. 59-83666 or Japanese Utility Model Laid-Open No. 60-28573 are known. I have.

[Problems to be solved by the invention]

By the way, the reaction force mechanism in the conventional integral type power steering device has a flat back surface of the reaction force plunger or a curved surface having a curvature smaller than the inner diameter of the housing around the worm shaft. However, when the back pressure is larger than the reaction pressure and slides to the rear side of the reaction plunger, the rear surface of the reaction force plunger is caught on the inner surface of the housing, and there is a problem that steering feeling is poor.

The present invention has been made in view of such a situation, and prevents the reaction force plunger and the housing from galling even when the back pressure is greater than the reaction force pressure and the reaction force plunger slides to the rear side. It is an object of the present invention to provide an integral type power steering device capable of obtaining a good steering feeling.

[Means for solving the problem]

According to the present invention, as a means for achieving the above object, a stub shaft rotationally driven by a steering handle, a worm shaft arranged on the same axis as the stub shaft, and each of these shafts are provided so as to be integrally rotatable. A control valve comprising a pair of valve members, a piston fitted to the worm shaft via a ball screw, reciprocating in a cylinder provided in the gear housing, and meshing with a rack formed on the piston, In an integral type power steering device provided with a sector gear rotating with reciprocation of a piston, a reaction force plunger is slidably fitted in a hole formed in the worm shaft, and the reaction force plunger is Is engaged with an engaging portion formed on the outer periphery of the stub shaft, and the hydraulic pressure discharged from the oil pump is applied to the rear side of the reaction force plunger. The back of the plunger, characterized in that to arrange the rotatable ball in contact with the housing of the worm shaft outer peripheral portion.

[Action]

In the integral type power steering device according to the present invention, when the stub shaft is rotated by the steering handle and a relative rotational displacement is generated between the worm shaft and the worm shaft, the stub shaft is pressed by the engaging portion of the stub shaft and retreated. On the back side of the force plunger, a force acts to push both axes back to the neutral position due to hydraulic pressure,
This force is transmitted to the steering wheel as a steering reaction force. Since the oil pressure changes according to the vehicle speed, the steering reaction force also changes accordingly.

By the way, when the back pressure is larger than the reaction pressure, the reaction force plunger moves backward, that is, moves to the rear side, and the rear side eventually comes into contact with the inner diameter portion of the housing. The back of the plunger does not touch directly,
Indirect contact will be made via the ball. Since the ball rotates when it comes into contact with the housing, the contact resistance with the housing is extremely small, galling between the plunger and the housing can be prevented, and a good steering feeling can be obtained.

〔Example〕

Hereinafter, the present invention will be described with reference to the illustrated embodiments. FIG. 1 is a longitudinal sectional view of an integral type power steering device according to an embodiment of the present invention. A piston (6) is slidable in a cylinder portion (4) in a gear housing (2). Mated with
The inside of the cylinder (4) is partitioned into two pressure chambers (8) and (10) by the piston (6). A rack (12) is provided on the side surface (the lower surface in FIG. 1) of the piston (6).
The rack (12) is meshed with a sector gear (14) interlocking with a steering wheel (not shown), and rotates forward and backward with the reciprocation of the piston (6). .

A ball screw groove (18) is screwed into the hole (16) at the axial center of the piston (6), and a number of balls (1) in the groove (18) are screwed.
The worm shaft (output shaft) (20) is screwed through 9). A cylindrical portion (22a) of the valve housing (22) is fitted to one end of the gear housing (2), and a bolt (24)
Has been fixed by. This valve housing (22)
A stub shaft (input shaft) (26) is disposed inside the worm shaft so that the worm shaft (20) is aligned with the worm shaft (20). Worm axis (2
A large-diameter cylindrical portion (20a) is formed at the end of the stub shaft (26) on the side of the stub shaft (26). Are fitted. These two shafts (20) and (26) are connected by a torsion bar (30) inserted into a hole in the shaft center. Further, the inner surface of the worm shaft (20) and the outer surface of the stub shaft (26) are failed to allow a predetermined amount of relative rotation of the two shafts (20) and (26) and to restrict further rotation. Safe (32) is formed. The stub shaft (26) is connected to a steering handle (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) (36) is fitted around the outer periphery thereof. The valve sleeve (36) is connected to a worm shaft (20) via a pin (38) so as to rotate integrally therewith. The valve rotor (34) and the valve sleeve (36) enable a rotary type. A control valve (40) is configured.

The control valve (40) is connected to the valve housing (2
It communicates with the oil pump through the supply port (42) formed in 2) and the tank through the return port (44), and the control valve (40) is switched by operating the steering handle. Then, the pressure oil discharged from the oil pump is supplied to one of the pressure chambers (8) and (10), and the other pressure chamber is communicated with the tank to generate a pressure difference between the two chambers. The piston (6) is operated by the pressure difference to apply an assisting force in the steering direction.

The stub shaft (2) of the large-diameter cylindrical part (20a) of the worm shaft (20)
6) The side end is fitted to the outer periphery of the valve sleeve (36) and a ball bearing (2) that rotatably supports both the worm shaft (20) and the stub shaft (26) with respect to the valve housing (22). 46) constitutes the inner race (46a). The outer race (46b) of the ball bearing (46) is inserted between the outer peripheral surface of the cylindrical portion (20a) of the worm shaft (20) and the cylindrical portion (22a) of the valve housing (22) and has a screw portion (48). It is held at the bottom of the valve housing (22) by an adjusting plug (50) fixed by the.

A reaction mechanism (51) is provided near the cylinder at a portion where the worm shaft (20) and the stub shaft (26) are fitted, and the reaction mechanism (51) is shown in FIGS. This will be described in detail with reference to the drawings. Two protrusions (52) are formed at symmetrical positions on the outer periphery of the stub shaft (26), and the worm shaft (20)
Are formed with holes (54) in a direction perpendicular to both side surfaces of the two projections (52), and a reaction force plunger (56) is slidably fitted in each of the holes (54). doing.

The adjusting force of the adjusting plug (50)
An annular groove (50a) is formed on the inner surface of the portion located around 1), and seal members (58) are provided on both sides of the annular groove (50a).
Is installed. Adjusting plug (5
An annular space (60) is formed between the outer peripheral surface of (0) and the inner peripheral surface of the valve housing (22), and an O-ring (62) is provided near the cylinder portion (4) of this space (60). It is installed. Further, the cylindrical portion (22a) of the valve housing (22)
An annular groove (22b) is formed on the outer peripheral surface of the annular groove (2b).
O-rings (64) are mounted on both sides of 2b).

Further, pressure oil from a hydraulic pressure source is introduced into the annular groove (22b) through an introduction port (not shown) formed in the gear housing (2). The valve housing (22) has a passage hole (22c) communicating the outer peripheral annular groove (22b) of the valve housing (22) and the inner peripheral annular space (60) with the adjusting plug (5).
0) has a passage hole (5) communicating the annular space (60) with the annular groove (50a) on the inner peripheral side of the adjusting plug (50).
0b) is provided. Therefore, the valve housing (2
The pressure oil introduced into the annular groove (22b) in (2) passes through the passage hole (22).
c), annular space (60), passage hole (50b) and annular groove (50)
Introduced on the back side of the reaction plunger (56) via a). The hydraulic source may be a common pump with the power steering device, or a sub-pump or the like that increases or decreases the discharge amount according to the vehicle speed.

As shown in FIG. 2, for example, steel balls (68) are disposed on the back surface of the reaction force plungers (56), and these balls (68) will be described in detail later. When the back pressure becomes larger than the reaction pressure and each reaction force plunger (56) moves to the rear side, the adjusting plug (housing) (50) rotates in contact with the inner diameter portion of the adjusting plug (housing) (50). Has become. As a result, the resistance at the time of contact becomes extremely small, and it is possible to effectively prevent poor steering feeling due to galling between the reaction plunger (56) and the adjusting plug (50). I have.

 Next, the operation of the present embodiment will be described.

When the stub shaft (26) is rotated by the operation of the steering handle, a relative rotational displacement occurs between the stub shaft (26) and the worm shaft (20), so that the stub shaft (26) is formed on the stub shaft (26). The relative rotational displacement also occurs between the valve rotor (34) and the valve sleeve (36) connected to the worm shaft (20), whereby the flow path in the control valve (40) is switched, and the cylinder section (4) One of the two pressure chambers (8) and (10) communicates with the oil pump, and the other communicates with the tank, whereby the piston (6) moves to operate as a power steering device.

When the stub shaft (26) and the worm shaft (20) rotate relative to each other as described above, the projections (52) of the stub shaft (26) constituting the reaction force mechanism (51) cause the reaction force facing both sides thereof. Press one of the plungers (56) to retract. On the back side of each reaction plunger (56), pressure oil discharged from an oil pump whose discharge amount increases in accordance with an increase in vehicle speed is filled with an annular groove (22b), a passage hole (22c), and an annular space ( 60), introduced through the passage hole (50b) and the annular groove (50a), the hydraulic pressure causes the reaction force plunger (56), which is pressed and retracted, to protrude from the stub shaft (26). 52) is applied to the neutral position (the state shown in FIG. 2). This rotational force is transmitted to the steering wheel as a steering reaction force, and steering stability during high-speed running can be improved.

By the way, each reaction plunger (56) is compared with the hydraulic pressure (reaction pressure) acting on the back side of each reaction plunger (56).
When the force (back pressure) for retracting the piston becomes large, each reaction plunger (56) moves to the rear side, and eventually the rear surface comes into contact with the inside diameter of the adjusting plug (50), causing galling. In this embodiment, since the balls (68) are arranged on the back of each reaction force plunger (56), the back of each reaction force plunger (56) is directly connected to the adjusting plug (50). , But indirectly via the ball (68). The balls (68) rotate freely when they come into contact with the inner diameter of the adjusting plug (50), so that the contact resistance is extremely small, and the ball (68) is connected to the reaction force plunger (56). Galling with the adjusting plug (50) can be effectively prevented. Therefore, a good steering feeling can always be obtained.

FIGS. 3 and 4 show another embodiment of the present invention, in which a reaction mechanism (151) is used instead of the reaction mechanism (51) in the above embodiment. Is exactly the same as the above embodiment.

That is, in this embodiment, an annular large diameter portion (102) is formed on the outer periphery of the stub shaft (26), and four concave portions (104) are provided in the large diameter portion (102) at equal intervals in the circumferential direction. Have been. These recesses (104) consist of two inclined surfaces. On the other hand, in the large-diameter portion (20a) of the worm shaft (20), four holes (106) penetrating in the diametric direction at equal intervals in the circumferential direction are formed. A reaction plunger (110) having a ball (108) is tightly slidably fitted. The hydraulic pressure acts on the back side of each of the reaction force plungers (110) in the same manner as in the above-described embodiment, and the ball (68) of the above-described embodiment is provided on the back of each reaction force plunger (110). Balls (112) having the same functions as in (1) are provided.

In the present embodiment, the stub shaft (26) and the worm shaft (2
When (0) rotates relatively, the center of each ball (108) shifts from the center of each recess (104) and is pushed up by the inclined surface of the recess (104). Then, in the same manner as in the above embodiment, the ball (108) pushes the inclined surface of the concave portion (104) to return to the neutral position by the hydraulic pressure acting on the back surface of the reaction force plunger (110), and this force is used for steering. It is transmitted to the steering wheel as a reaction force.

On the other hand, when the back pressure for retracting each reaction force plunger (110) is larger than the reaction force pressure acting on the back side of each reaction force plunger (110), each reaction force plunger (110) Will move to the back side, but each ball (1
Since 12) rotates freely in contact with the adjusting plug (50), the contact resistance is extremely small, and a good steering feeling can be obtained, as in the previous embodiment. If the balls (108) and (112) have the same diameter, the workability can be improved. Also, put the ball (112) on the plunger (1
In the case of the configuration of press-fitting in 10), the contact resistance is slightly increased, but the effect that the processing of the contact portion is facilitated as compared with the conventional configuration is obtained.

[Effect of the invention]

As described above, in the present invention, the back pressure is larger than the reaction force pressure because the rotatable ball is arranged on the rear surface of the reaction force plunger in contact with the housing on the outer periphery of the worm shaft. Even when the reaction force plunger moves to the rear side, galling between the reaction force plunger and the housing is prevented, and a good steering feeling can always be obtained.

[Brief description of the drawings]

1 is a longitudinal sectional view showing an integral type power steering device according to an embodiment of the present invention, FIG. 2 is a transverse sectional view showing a reaction force mechanism thereof, and FIG. 3 is another embodiment of the present invention. 1 is a diagram corresponding to FIG. 1, FIG. 4 is a diagram corresponding to FIG. 2, and FIG. 5 is an enlarged view of a main part of FIG. (2) ... gear housing, (4) ... cylinder part,
(6) ... piston, (12) ... rack, (14) ... sector gear, (20) ... worm shaft, (26) ... stub shaft, (34), (36) ... valve member, ( 40) Control valve, (52) Projection (engagement part), (54) Hole,
(56), (110) ... Reaction plunger, (68), (112)
... Ball, (104) ... recess (engaging part), (106) ...
hole.

Claims (1)

(57) [Scope of request for utility model registration] 1. A stub shaft rotatably driven by a steering handle, a worm shaft disposed on the same axis as the stub shaft, and a pair of valve members provided so as to be integrally rotatable with each of these shafts. A control valve, a piston fitted to the worm shaft via a ball screw, reciprocating in a cylinder provided in the gear housing, and meshing with a rack formed on the piston, and the reciprocating motion of the piston In the integral type power steering device provided with a sector gear that rotates by rotation, a reaction force plunger is slidably fitted into a hole formed in the worm shaft, and the reaction force plunger is fitted around the outer periphery of the stub shaft. The oil pressure from the oil pump is applied to the back side of the reaction force plunger, and the rear surface of the reaction force plunger is Integral power steering apparatus characterized in that a rotatable ball in contact with the housing of Jikugaishu portion.