JP2509938Y2 - Power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a power steering apparatus, and more particularly to a power steering apparatus having a reaction force mechanism.

[Conventional technology]

FIG. 8 is a vertical cross-sectional view of a conventional integral type power steering apparatus, and FIG. 9 is a cross-sectional view of a reaction force mechanism portion. A piston is provided in a cylinder portion (4) in a gear housing (2). (6) is slidably fitted, and the inside of the cylinder (4) is divided into two pressure chambers (8) and (10) by this piston (6). A rack (12) is formed on a side surface (a lower surface in FIG. 8) of the piston (6), and a sector gear (14) interlocking with a steering wheel (not shown) is meshed with the rack (12) to form a piston ( With the reciprocating movement of 6), it is designed to rotate forward and backward.

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
0) has a large-diameter cylindrical portion (20a) formed at the end on the stub shaft (26) side, and the tip portion of the stub shaft (26) is inserted into the cylindrical portion (20a) via a bearing (28). Are fitted together. The two shafts (20) and (26) are connected by a torsion bar (30) inserted in a hole at the center of the shafts. In addition, the inner surface of the worm shaft (20) and the outer surface of the stub shaft (26) allow a predetermined amount of relative rotation of both shafts (20) and (26), and limit the 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 fitted with a 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 ends are fitted to the outer circumference of the sleeve (36), respectively, and a ball bearing (rotatably supporting both the worm shaft (20) and the stub shaft (26) with respect to the valve housing (22) ( It composes the inner race (46a) of 46). The ball bearing (46 outer race (46b) is inserted between the outer peripheral surface of the tubular portion (20a) of the worm shaft (20) and the tubular portion (22a) of the valve housing (22) by the screw portion (48). It is held at the bottom of the valve housing (22) by a fixed adjusting plug (50).

A reaction force mechanism (51) is provided near the cylinder in the portion where the worm shaft (20) and the stub shaft (26) are fitted. The reaction force mechanism (51) will be described. A plurality of (three in this embodiment) circular holes (52) radially extending through the large-diameter cylindrical portion (20a) of the worm shaft (20) at equal intervals in the circumferential direction.
Are formed. A reaction force plunger (54) is slidably fitted in each of the circular holes (52). An arcuate recess is formed on the inner end surface of the reaction force plunger (54), and the ball (56) is held in the recess.
On the other hand, on the outer circumference of the stub shaft (26), the large annular portion (26
a) is provided, and in this large diameter portion (26a) there are three V-shaped grooves (5
7) has been formed. Then, due to the hydraulic pressure introduced into the outer space (hydraulic reaction chamber) of the reaction force plunger (54) in the circular hole (52), the ball (56) is moved through the reaction force plunger (54) to move the stub shaft (26). The V-groove (57) is pressed to generate a steering reaction force.

[Problems to be solved by the device]

In the conventional power steering apparatus, the hydraulic pressure introduced into the hydraulic reaction force chamber rises according to the traveling speed of the vehicle, but during the operation of the reaction force mechanism (51), the worm shaft and the stub shaft move. When the relative angular displacement occurs, there is a problem that the reaction force oil pressure cannot be changed unless another device having a function of adjusting the oil pressure of the reaction force chamber is added. Further, the addition of the device may increase the size, interfere with other parts of the vehicle, and increase the cost.

The present invention has been made in view of the current situation, and an object of the present invention is to provide a power steering apparatus that can change the reaction force hydraulic pressure according to the operation amount of the reaction force mechanism.

[Means for solving the problem]

As a means for achieving the above object, the present invention provides an input shaft that is rotated by a steering wheel, an output shaft that is arranged on the same axis as the input shaft, and that is capable of relative rotation, and that is rotatable integrally with both of these shafts. A control valve including a valve member provided and a reaction force mechanism provided between the shafts are provided, and the reaction mechanism has a radial hole formed in one of the shafts and a slide hole in the hole. It is formed on the reaction force plunger movably fitted to the ball, a ball held in a concave portion provided eccentrically from the center of the outer diameter of the inner side end surface of the reaction force plunger, and the outer surface of the other shaft. A power steering device comprising an axial groove in which the ball is pressed by the hydraulic pressure acting on the reaction force plunger, the displacement of the reaction force plunger in the radial hole between the radial hole and the reaction force plunger. Characterized by being adapted to form an orifice throttle amount is changed in accordance with.

[Action]

In the power steering apparatus according to the present invention, the throttle amount of the orifice changes according to the displacement amount of the reaction force plunger in the radial hole. Therefore, the amount of pressure oil introduced into the hydraulic reaction chamber on the rear side of the reaction force plunger changes through the orifice, which changes the reaction hydraulic pressure according to the operation amount of the reaction mechanism. To be done.

〔Example〕

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral (151) is a reaction force mechanism, and the reaction force mechanism (151) is, for example, three at a regular interval in the circumferential direction on the worm shaft (20) (only one is shown in FIG. 1). ) A circular hole (152) is formed penetrating in the radial direction, and a reaction force plunger (154) is slidably and closely fitted in each circular hole (152). Reaction force plunger (15
4) has a recess (154a) formed on the inner end surface (lower end surface in FIG. 1), and the recess (154a) is larger than the diameter of the ball (156) held therein. It consists of a circular arc of diameter. Moreover, this recess (154)
As shown in FIG. 3, the center (0 ₁ ) thereof is provided at a position displaced in the radial direction from the axis (0 ₂ ) of the reaction force plunger (154). And the ball (156) is attached to the stub shaft (2
It is fitted in an axial V-shaped groove (157) formed on the outer surface of 6).

As shown in FIGS. 1 and 2, two parallel projections (158) are integrally provided on the outer side of the reaction force plunger (154), and both projections (158) are A stopper (16) press-fitted into the outer peripheral side opening of the circular hole (152).
It is fitted and locked in 0) and positioned around the shaft.

That is, as shown in FIGS. 1 and 2, the stopper (160) has a shallow circular dish shape, and the both protrusions (158) are fitted and locked in the center thereof. A substantially cross-shaped locking hole (162) is provided. Then, as shown in FIG. 3, when the neutrality of the reaction mechanism (151) is not obtained, the tip of the tool (164) such as a screwdriver that penetrates the locking hole (162) of the stopper (160). The both protrusions (1
58) to rotate the reaction force plunger (154) so that the neutral position of the reaction force mechanism (151) coincides with the hydraulic center and then press fit the stopper (160) into the circular hole (152). Thus, the reaction force plunger (154) is positioned around the shaft in the aligned state.

On the outer peripheral edge of the upper end of the reaction force plunger (154), the first
As shown in the figure, notches (166) are evenly provided on the circumference, and the inner circumferential surface of the circular hole (152) on the side of the stub shaft (26) is circumferentially spaced at equal intervals. End mill (168) with a diameter smaller than the diameter of the circular hole (152) at two or more locations, for example at two locations.
Processed diagonally with and each discharge groove (170) is provided,
By these both discharge grooves (170) and the notch (166),
An orifice whose amount of throttling changes according to the amount of sliding of the reaction force plunger (154) is formed. Then, with this orifice, the reaction force hydraulic pressure is adjusted according to the operation amount of the reaction force mechanism (151).

 Next, the operation of this embodiment will be described.

At the neutral position of the control valve when the reaction force mechanism (151) is assembled, as shown in FIG.
If the neutral position cannot be obtained, insert the tip of the tool (164) through the locking hole (162) of the stopper (160) between both protrusions (158) of the reaction force plunger (154). Then, rotate the reaction force plunger (154) while pushing it. Then
The reaction force plunger (154) moves the ball (15) in the V-shaped groove (157).
6) It rotates with respect to 6) and is aligned (the neutral position of the reaction force mechanism (151) coincides with the center of hydraulic pressure) at the lowest position. In that state, when the stopper (160) is press-fitted to the position shown in FIG. 1, the rotation of the reaction force plunger (154) around the shaft is restricted, and the aligned state is maintained. In addition, a circular hole (15
Since the stopper (160) is provided on the inlet side of 2), there is no risk that the reaction force plunger (154) will come out of the circular hole (152) and hit the housing side.

On the other hand, when a relative rotational displacement occurs between the worm shaft (20) and the stub shaft (26) during vehicle operation, the reaction force mechanism (15
The center of each ball (156) that composes 1) has a V-shaped groove (15
It is displaced from the center of 7) and pushed up by the inclined surface.

On the other hand, the pressure oil from the oil pump is supplied to the back side of each reaction force plunger (154), and the center of each ball (156) coincides with the center of each V-shaped groove (157) by the reaction force. Rotational force that tends to return to the neutral position (the state shown in FIG. 1) is generated. This rotational force is transmitted to the steering wheel as a steering reaction force.

By the way, when a relative rotational displacement occurs between the two shafts (20) and (26), the ball (156) moves into the V-shaped groove (157) as described above.
The reaction force plunger (154) is also pushed up by this, but the reaction force plunger (154) is also pushed up.
Is pushed up, the throttle diameter of the orifice formed by the notch (166) and the discharge groove (170) becomes gradually smaller.
Therefore, the amount of oil discharged through the orifice gradually decreases, and the reaction force hydraulic pressure gradually increases according to the operation amount of the reaction force mechanism (151). This phenomenon is also obtained when the handle is rotated left or right. Further, since the rotation of the reaction force plunger (154) is restricted by the stopper (160), the throttle amount of the orifice can be changed in proportion to the rotation angle of the stub shaft (26).

FIGS. 4 and 5 show a second embodiment of the present invention, in which the reaction force hydraulic pressure is gradually reduced according to the operation amount of the reaction force mechanism (151).

That is, the circular hole (1
As shown in FIG. 4, 52) has a small diameter only at the end on the stub shaft (26) side, and only this portion is in sliding contact with the reaction force plunger (154). On the outer peripheral surface of the stub shaft (26) side of the force plunger (154), for example, at two locations at equal intervals in the circumferential direction, one or more discharge grooves (270) that gradually become deeper toward the stub shaft (26) side. Is provided. The discharge groove (270) and the circular hole (152) constitute an orifice whose amount of throttling changes according to the amount of displacement of the reaction force plunger (154).

The other points are the same as those of the first embodiment.

Thus, by providing the discharge groove (270) in the reaction force plunger (154), the reaction force plunger (154) can be moved to
When pushed up by the relative rotational displacement of 0) and (26),
Contrary to the first embodiment, the throttle diameter of the orifice gradually increases, and the amount of oil discharged through the orifice gradually increases. Therefore, the reaction force hydraulic pressure gradually decreases according to the operation amount of the reaction force mechanism (151).

6 and 7 show a third embodiment of the present invention. Instead of the stopper (160) and the discharge groove (170) in the first embodiment, a stopper (360) and a discharge groove (370) are shown. Is used.

That is, as shown in FIGS. 6 and 7, the upper end of the reaction force plunger (154) is provided with four substantially triangular prism-shaped projections (358) at equal intervals in the circumferential direction. The operation groove (358a) is provided so as to divide these protrusions (358) into two.

Further, as shown in FIG. 7, the stopper (360) has a substantially cross shape in plan view whose end portions are located between the adjacent protrusions (358), and the outer edge portion thereof has the shape shown in FIG. As shown in Fig. 7, the lip portion (360a) is raised. Further, as shown in FIGS. 6 and 7, an operation hole (362) corresponding to the operation groove (358a) is provided in the central portion of the stopper (360), and the operation hole (362) is provided. ) Through the operation groove (358a), insert the tip of a tool (not shown),
In this state, the reaction force plunger (154) is aligned and the stopper (360) is press-fitted into the circular hole (152), so that the reaction force plunger (154) can be prevented from rotating in the aligned state.

On the other hand, the discharge groove (370) can be provided at one or more places. As shown in FIG. 6, for example, the diameter of the circular hole (152) can be set at two locations facing each other in the circumferential direction of the circular hole (152). Although it is formed by obliquely working with an end mill (not shown) having a smaller diameter than that of the discharge groove (170) in the first embodiment, its outer end (the sixth
The upper end in the figure) is located closer to the stub shaft (26) side than the upper end of the reaction force plunger (154).
Therefore, the orifice is formed only by processing the discharge groove (370) without processing the reaction force plunger (154).

In other respects, the structure is the same as that of the first embodiment and the operation is the same.

Then, by only processing the discharge groove (370), an orifice whose amount of throttling is changed according to the sliding amount of the reaction force plunger (154) is configured, which facilitates manufacturing.

In each of the above embodiments, the stopper (160),
(360) explained that the reaction force plunger (154) was held in the aligned state, but the neutral position of the reaction force mechanism (151) was initially aligned with the hydraulic center, or The stoppers (160) and (360) can be omitted if they can be matched by a mechanism.

[Effect of device]

As described above, the present invention forms an orifice between the reaction force plunger and the radial hole in which the reaction force plunger slides, forming an orifice whose amount of throttling changes according to the amount of displacement of the reaction force plunger. Therefore, the reaction force hydraulic pressure can be adjusted according to the operation amount of the reaction force mechanism at a low cost without increasing the size of the power steering apparatus.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an essential part showing a reaction force mechanism of a power steering apparatus according to a first embodiment of the present invention, FIG. 2 is a plan view of FIG.
FIG. 4 is an explanatory view showing the alignment method, and FIG. 4 is the second of the present invention.
An example corresponding to FIG. 1, FIG. 5 is a plan view of FIG. 4,
FIG. 6 is a view corresponding to FIG. 1 showing a third embodiment of the present invention, and FIG.
6 is a plan view of FIG. 6, FIG. 8, FIG. 10 and FIG. 11 are vertical cross-sectional views showing a conventional integral type power steering apparatus, respectively.
FIG. 9 is a cross-sectional view of the reaction force mechanism portion of FIG. (20) …… Worm shaft, (26) …… Stub shaft, (151)
…… Reaction force mechanism, (152) …… circular hole, (154) …… reaction force plunger, (156) …… ball, (157) …… V-shaped groove, (16
0), (360) …… Stopper, (166) …… Notch, (17
0), (270), (370) ... Discharge groove.

Claims (1)

(57) [Scope of utility model registration request] 1. An input shaft rotated by a steering wheel, an output shaft arranged on the same axis as the input shaft and capable of relative rotation, and a valve member provided on both shafts so as to be integrally rotatable. And a reaction force mechanism provided between the shafts, the reaction force mechanism being slidably fitted in a radial hole formed in one of the shafts. Formed on the outer surface of the reaction force plunger, the ball held in the concave portion provided eccentrically from the center of the outer diameter on the inner side end surface of the reaction force plunger, and the outer surface of the other shaft. In a power steering device including an axial groove in which the ball is pressed by an acting hydraulic pressure, between the radial hole and the reaction force plunger, a throttle amount is determined according to a displacement amount of the reaction force plunger in the radial hole. Changes Power steering apparatus characterized by the formation of the orifice.