JPS5820825B2 - Power steering device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a power steering device, in which a control valve mechanism that switches a hydraulic circuit to control the supply and discharge of pressure oil from an oil pump to a power cylinder can be installed in a relatively free position. It is something.

In conventional power steering devices, the control valve mechanism usually needs to be placed on the same axis as the steering wheel shaft.
The overall length was longer than that of a manual steering gear.

Therefore, as power steering devices have been adopted in small vehicles in recent years, it has become difficult to install conventional power steering devices, which have a long overall length, on small vehicles because of the installation space, especially the installation space in the axial direction. The disadvantage was that it was difficult.

In view of these points, the present invention makes it possible to install the control valve mechanism at a position off the steering wheel axis, thereby reducing the overall length to approximately the entire length of a manual steering gear. To provide a power steering device that can be easily installed.

The present invention will be described in detail below with reference to the illustrated embodiment. In FIG. 1, reference numeral 1 denotes an input shaft rotatably supported in a housing 2 via a bearing 3, and is linked to a steering wheel (not shown).

Reference numeral 4 denotes an output shaft rotatably supported in the housing 2 through bearings 5 and 6. A pinion formed on the output shaft 4 is meshed with the rack rod 1, and the rack rod 7 is outputted to the housing 1. Supported so as to be slidable in a direction perpendicular to the shaft 4,
Both ends thereof are linked to steering wheels (not shown).

The input shaft 1 and the output shaft 4 are arranged on the same axis, and a protrusion formed at the tip of the input shaft 1 is connected to the end of the output shaft 4 via a bushing 8 that receives forces in the thrust direction and radial direction. By fitting into the formed hole, the input shaft 1 and the output shaft 4 can rotate relative to each other.

Flange portions 9 and 10 facing each other are formed at the tip of the input shaft 1 and the end of the output shaft 4, respectively, and as shown in FIG. A plurality of grooves 11 are formed on the end face of the flange portion 10 on the output shaft 4 side, and a plurality of protrusions 12 are formed at predetermined intervals, and the grooves 11 and protrusions 12 are arranged in a required manner in the circumferential direction. By engaging each other with a gap, the input shaft 1 and the output shaft 4 can rotate relative to each other by an amount allowed by the gap.

Furthermore, identical gears 13 and 14 are fixed to the tip of the input shaft 1 and the distal end of the output shaft 4, respectively, as shown in FIG. Pins 15° and 16 are press-fitted and fixed.

Then, by sandwiching both pins 15 and 16 between the ends of an annular spring 11 disposed on the outer periphery of the flange portion 9.10 (see FIG. 2), normally both pins 1516 are held by the spring 17. They are located on the same axis, so that the protrusion 12 on the output shaft 4 side is usually located in the center of the groove 11 on the input shaft 1 side.

Therefore, the input shaft 1 resists the spring 17 and the projection 12
When the external force applied to both shafts 1 and 4 is removed, both shafts 1 and 4 are returned to their original relative rotation by the spring 17. The angle is returned to zero.

In FIG. 2, reference numeral 18 denotes a control valve mechanism having a conventionally well-known configuration, which includes a rod 19 slidably supported on the housing 2 and a spool valve 20 attached to this rod. , 23 is provided to the power cylinder 28 via the port 24 and the pipe line 25 or via the port 26 and the pipe line 27 by the horizontal displacement of the rod 19 and the spool valve 20. It has a function.

The power cylinder 28 is equipped with a piston 29 fixed to the rack rod 7, and when pressure oil is supplied by displacement of the spool valve 20 constituting the control valve mechanism 18, the power cylinder 28 turns the steering wheel. It is meant to assist.

Between the control valve mechanism 18 and the input/output shafts 1, 4, there is a mechanism that converts the relative rotational displacement between the two shafts 1, 4 into a linear displacement and transmits it to the spool valve 20 of the control valve mechanism 18, which is known in the art. Conversion mechanism 30 for performing the same function as the power steering device of
has been established.

In this embodiment, a conventionally well-known Oldham joint is used as the conversion mechanism 30.

That is, in FIG. 1, 31 and 32 are gears of the same shape that mesh with the gears 13 and 14, respectively, 33 is a protrusion with a rectangular cross section protruding from the end face of one gear 31, and 34 is an end face of the other gear 32. The protrusion 35 has a rectangular cross section and is protruded perpendicularly to the protrusion 33. 35 is a disc interposed between the opposing protrusions 33 and 34, and grooves are carved on both end faces of the disc 35 to be perpendicular to each other. are slidably engaged with the projections 33 and 34, respectively, thereby forming an Oldham joint.

Then, by rotatably supporting the rotating shaft 36 of one gear 32 constituting this Oldham joint in the housing 2 and connecting the rod 19 to the rotating shaft 37 of the other gear 31, the converting mechanism 30 It consists of

In FIGS. 1 and 2, 38 is a seal that prevents lubricating grease from leaking from between the input shaft 1 and housing 2, and 39.40 is a seal that prevents oil from leaking from the spool valve 20 side. , 41 is a cover.

With the above configuration, when the vehicle is traveling straight, that is, when the input shaft 1 and the output shaft 4 are stationary and the relative rotational displacement between them is zero, the Gears 31 and 32 of the conversion mechanism 30 that mesh with the gears 13 and 14
are also stationary, and in this state, the rotation axes 36 and 37 of both gears 31 and 32 are located on the same axis;
A spool valve 20 connected via a rod 19 to the spool valve 20 is held in a neutral position.

Therefore, the pressure oil from the oil pump 21 is not introduced into the power cylinder 28, and the vehicle can continue to travel straight.

When the input shaft 1 is rotated by operating the steering bundle (not shown) from this state, the output shaft 4 is interlocked with the steering wheel via the rack rod 7 and receives road surface resistance from the steering wheel. is rotated relative to the output shaft 4 against the spring 17.

Then, the gear 31 meshed with the gear 13 fixed to the input shaft 1 tries to rotate as the input shaft 1 rotates, but the other gear that rotates integrally with the gear 31 via the Oldham joint Since the gear 32 is still meshing with the gear 14 of the output shaft 4 which is in a stationary state, the gear 31 is in mesh with the gear 14 of the output shaft 4 which is still in a stationary state.
Due to the driving force, the rod 19 is displaced along the sliding direction without rotating.

When the gear 31 is displaced from its normal rest position, the spool valve 20, which is interlocked with the gear 31 via the rod 19, is also displaced from its neutral position, switching the hydraulic circuit and shutting down the power cylinder 28 as is well known in the art. Pressure oil is supplied to assist the turning of the steering wheel.

When the steering wheel starts turning, the output shaft 4, which is interlocked with the steering wheel through the rack rod 7, starts rotating in the rotation direction of the input shaft 1.The input shaft 1 and the output shaft 4 are at the same speed. When it starts to rotate, the gears 31 and 32 that make up the Oldham coupling also start to rotate in the same direction and at the same speed, but since the output shaft 4 is receiving steering resistance from the road surface when the vehicle is turning, the input shaft 1
The input shaft 1 rotates at the same speed as the input shaft 1 while being rotationally displaced relative to the gear 31 and the valve spool 20 interlocked with the gear 31 and the valve spool 20 that also maintains a displaced state and supplies pressure oil to the power cylinder 28. continue.

During this time, the driver senses the acting force of the spring 17, which attempts to return the amount of relative rotational displacement between the input and output shafts 1 and 4 to zero, as an operational reaction force.

In addition, since this spring 17 returns the relative rotational displacement between the input shaft 1 and the output shaft 4 to zero when the steering bundle is returned to the neutral position, the gear 31 and the valve spool 20 are also reliably returned to the original neutral position. It will be returned to.

Note that if the gear 31 is moved largely in the axial direction of the rod 19, the gear 13 will be out of mesh with the gear 13, but generally the amount of displacement of the spool valve 20 that interlocks with the gear 31 may be small, and 31, in other words, the relative rotational displacement between the input shaft 1 and the output shaft 4 is the spool valve 2.
Since the gap between the groove 11 and the protrusion 12 can be adjusted to match the amount of displacement of 0, the gear 31 and the gear 13 will never come out of mesh.

If it is necessary to displace the spool valve 20 by a large amount, the gear 31 may be connected to the gear 13 by a link or the like so that it can rotate around the gear 31 while maintaining its meshing state, and the rod 19 may be connected to this link or the like. It's okay.

Furthermore, in the above embodiment, an Oldham joint is used as the conversion mechanism 30 that converts the relative rotational displacement between the input shaft 1 and the output shaft 4 into linear displacement, but like the Oldham joint, rotation is transmitted between two parallel axes. It goes without saying that mechanisms with other configurations may be used as long as they are capable of doing so.

4 and 5 respectively show the main parts of different conversion mechanisms. In the mechanism shown in FIG. 4, a spline is formed on the shaft of the gear 31, 32, and a spline that engages with the spline is formed on the spherical portions 42 at both ends. Both gears 31.3
2 are connected.

Further, in the mechanism shown in FIG. 5, both gears 31 and 32 are connected by a pair of hook universal joints 44, so that changes in the gap between the two joints 44 can be absorbed by a spline or the like.

As described above, the present invention utilizes a link mechanism such as an Oldham joint that transmits rotation between two parallel axes that are different from each other.
A conversion mechanism is constructed that converts the relative rotational displacement between the input shaft and the output shaft into a linear displacement based on the distance between the two parallel axes, and the spool valve of the antibacterial valve mechanism is linked to this conversion mechanism. Because of this, the control valve mechanism and structure can be installed at a position off the bundle axis, and therefore the overall length can be shortened compared to conventional power steering devices.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIGS. 2 and 3 are cross-sectional views taken along the lines ■-■ and at-m in FIG. 1, respectively, and FIGS. 4 and 5 are respectively FIG. 2 is a sectional view and a plan view showing main parts of the conversion mechanism, which are different from those shown in the above figure. 1...Input shaft, 4...Output shaft, 18.
... Control valve mechanism, 20 ... Spool valve, 21 ... Oil pump, 29 ...
Power cylinder, 30... Conversion mechanism.

Claims (1)

[Claims] 1. In a power steering device equipped with an input shaft linked to a steering wheel, an output shaft linked to steering wheels, and a control valve mechanism that switches a hydraulic circuit to control the supply and discharge of pressure oil from an oil pump to a power cylinder. , has two axes arranged almost parallel to the input shaft and the output shaft, and a link mechanism such as an Oldham joint that can transmit rotation to these two parallel axes in different states without making mistakes. A conversion mechanism is provided for transmitting rotation from each using a gear or the like and converting the relative rotational displacement between the input shaft and the output shaft into a linear displacement as a magnitude of the axis misalignment between the two parallel axes, and the above-mentioned control A power steering device characterized in that a spool valve of a valve mechanism is linked to a conversion mechanism thereof.