JPS61139560A - Electrical power steering device - Google Patents

Abstract

PURPOSE:To make it possible to faciliate the arrangement of an electrical power steering device onto a vehicle, by forming a rack-and-pinion section through which a steering input is transmitted and an auxiliary power section for transmitting auxiliary power, in unit bodies, respectively, and by coupling both sections through a coupling means. CONSTITUTION:Gear sections 16, 17 of a pinion shaft 5 rotated by turning a steering wheel and a rack shaft 7 extending orthogonal to the pinion shaft 5, are incorporated in a housing 2 together with a support device 18 for pressurizing the mesh between the gears 16, 17, thereby a rack-and-pinion section 20 is established. An auxiliary power section for giving auziliary power to the rack shaft 7is integraly incorporated in a housing 28 so that the power of an electrical motor 8 is transmitted to a ball screw section 30 provided on the rack shaft 7 through a power transmission device 10. Further, the housings 22, 28 are intengrally coupled with each other through the intermediary of a coupling member 32 covering the rack shaft 7 to protect the same.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a steering device for a vehicle, etc., and more specifically to an improvement of a rack and pinion steering device having an electric power assist device for reducing steering force on a steering wheel. Regarding.

(Prior Art) A conventionally widely used rack and pinion steering device (as shown in Japanese Patent Publication No. 49-39454, for example) includes a rack shaft supported in a reciprocating manner within a housing; Steering force was transmitted by a pinion shaft having a pinion part that intersects and meshes with the rack part of the rack shaft within the housing.

On the other hand, a rack and pinion type power steering device is known that provides power assistance by transmitting hydraulic pressure or power from an electric motor onto the rack shaft when a large steering force is required, such as when the vehicle is stationary.

There are many examples of devices that utilize such hydraulic pressure, but an example of an electric power (auxiliary) steering device is disclosed in Japanese Patent Application No. 58-132.
827 and the type shown in US Pat. No. 4,415,054.

These electric power steering devices have a ball screw disposed on a rack shaft that has a rack part that engages with a pinion part of a pinion shaft that receives steering input from a steering handle, and an electric motor is connected to the motor through this ball screw. It is designed to transmit power to the rack shaft. In these steering devices, the rack and pinion part and the ball screw part are held in an integrated housing, and the electric motor is coaxially attached to the ball screw part (US Pat. No. 4415).
No. 054) or with different shafts (Patent Application No. 13282-1982)
7) Provided.

(Problems to be Solved by the Invention) In the conventional rack and pinion steering device that receives power assistance from an electric motor as described above, a rack and pinion part, a ball screw part, etc. are arranged in an integrated housing, and As electric motors and the like are arranged coaxially or non-coaxially, several problems arise.

First, because the electric motor for power assistance is installed inside the housing, space is not a problem with the steering device without an electric motor as shown in the aforementioned Japanese Patent Publication No. 49-39454. The above problem occurs.

That is, since various devices are arranged in a complicated manner in the engine room of the vehicle to which the steering device is attached, the installation position of the electric motor is restricted, resulting in a complicated housing shape.

In addition, if the shape of the vehicle or the equipment in the engine room differs due to differences in specifications, and the installation positions of each part of the steering device are different, it is necessary to prepare housings, rack shafts, etc. that correspond to each specification. .

Furthermore, if the specifications of the vehicle differ, the required steering assist force may also change, which can be handled by changing the capacity of the electric motor.

Therefore, depending on the size of the electric motor, housings and the like must be prepared in the specified number.

Furthermore, since the rack and pinion section, ball screw section, and electric motor section are installed internally or externally in the integrated housing, if there is a design change in one of these sections, the entire device will have to be changed. There are also some drawbacks.

As mentioned above, in the conventional electric power auxiliary rack and pinion steering system, each component is provided in an integrated housing, so there is little freedom in design and manufacturing, and it is possible to produce a large variety in small quantities. This has the problem that it tends to lead to high costs.

Therefore, it is an object of the present invention to provide an electric power steering system in which the arrangement of each component can be easily changed, can easily accommodate changes in specifications or design, and can be mass-produced as a common unit. Therefore, the present invention solves the above-mentioned problems and achieves the object.

(Means for Solving the Problems) The present invention achieves the above object by: a rotating shaft means directly driven by a handle; a first housing; and a steering wheel disposed within the housing to linearly reciprocate a rack formed on the elongated member; and a pinion gear that engages the rack within the first housing and is fixed to the rotating shaft means. a ball comprising: a screw means formed on a portion of the elongated member; a nut means covering at least a portion of the screw means; and a ball disposed between the screw means and the nut means. a screw means, a second housing containing the ball screw means, an electric motor, and a power transmission means that engages the nut means and the electric motor to transmit rotational output of the electric motor to the nut means; a second unit comprising; a connecting means for connecting the first unit and the second unit; a means for detecting torque applied to the rotating shaft means;
means for controlling the electric motor in response to the detection means; and 7, when assembling the unit, the relative position of the pinion part and the ball screw part in the axial direction, and the position of the electric motor in the circumferential direction; This is achieved by using an electric power steering device that can be relatively easily handled during assembly by changing only the connecting means of a simple configuration to handle the misalignment of the left and right sides.

(Example) Examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows the entire electric power steering apparatus according to the present invention, and FIGS. 2 and 3 show partial cross-sectional views of the main parts of the first and second embodiments.

In FIG. 1, a handle 1 is rotatably fixed to a handle shaft 2, and the handle shaft 2 is connected to a pinion shaft 5 via a universal joint 6 and the like. The pinion shaft 5 meshes with a rack shaft 7 that extends across the pinion shaft 5 within the housing 22, and the rack and pinion portion 2
0 is formed. A ball screw section 3 is provided on the rack shaft 7, and an electric motor 8 is connected to the ball screw section 3 via a power transmission device 10. The housing 22 is fixed to the vehicle body by brackets 14, 15, and the entire steering device is suspended on the vehicle body. Ball joints (not shown) are attached to both ends of the rack shaft 7 and are connected to steering wheels via knuckle arms or the like. The electric motor 8 is connected to a control circuit 11 installed in another part of the vehicle, and this control circuit 11 receives power from a power source 12, for example, from an input torque detector 4 installed on the steering wheel shaft 2. The output of the electric motor 8 is controlled based on information regarding input torque and information from the vehicle speed detector 13.

2 and 3 are cross sections taken along the rack axis 7 of the steering device shown in FIG. 1, and the embodiment shown in FIG. 3 shows the electric motor 8 of the embodiment shown in FIG. It is arranged with seven rotations. Therefore, the configurations are exactly the same except for the difference in position.

The steering device according to the present invention will be explained in more detail with reference to FIGS. 2 and 3.

A pinion gear portion 16 is rotatably supported at the tip of the pinion shaft 6 within a wedge leg 22 provided with the pinion gear portion 16 . On the other hand, the rack shaft 7 has a rack gear part 17, and the housing 2
2, the pinion gear part 16 meshes with the pinion gear part 16, and is supported so as to be able to reciprocate in the axial direction. The rack gear section and the pinion gear section 16 constitute a rack and pinion section 20, which supports the meshing of the pinion gear section 16 and the rack gear section 17 installed inside the housing 22 from the back side of the rack shaft 7, and applies meshing preload to the lever. A support device 18 is provided on the housing 22 . This support device 18 is a pressure device that comes into contact with the back surface of the rack shaft 7 and receives the load in the radial direction.
Pad 18a1 Pinion gear part 16 and rack gear part 17
A spring 19 that applies an engagement preload to the engagement portion of the □ via a pressure pad 1B'a, and a lid 1 that allows adjustment of the engagement preload.
8b1 and a lock nut 21 for adjusting and fixing the lid 18b. A bracket 15 for fixing the steering device to the vehicle is attached adjacent to the meshing portion of the pinion gear portion 16 and rack gear portion 17 of the housing 22.

A ball screw portion 30 is provided on the axis on which the rack shaft 7 extends.
is provided in the housing 28, and the electric motor 8 is connected to the power transmission device 10 as described above to the ball screw portion 30.
connected via. The ball screw part 30 is
A worm 29 is provided with a spiral groove cut on the rack shaft 7, and a worm 29 is rotatably disposed within the housing 28 via bearings 26 and 27, covering a part of the worm 29 and concentrically with the rack shaft 7. It is composed of a nut member 25 which also has a spiral groove on its circumferential surface, and a number of balls 33 arranged between the worm 29 and the grooves of the nut member 25. The ball 33 is configured to return to the circulation hole from the circulation hole provided in the nut member 25 through the above-mentioned spiral groove, and by the transfer and circulation of the ball 33, the air is removed from the electric motor 8. transmission of power and smooth reciprocation of the rack shaft.

The housing 28 is arranged to cover a part of the worm 29 of the rack shaft 7, and a member 30 that applies preload to the bearings 26 and 27 is screwed to one end (the upper pressure end in FIGS. 2 and 3) of the housing 28 and a lock nut. It is fixed by 31. Lid member 30
A bracket 14 is attached to the bracket 1.
4 fixes the steering device to the vehicle body together with a bracket 15 on the housing 2'2.

On the other hand, the other end of the housing 28 (the upper right end in FIGS. 2 and 3) is connected to the housing 22 by a connecting member 32. The connecting member 32 has both ends connected to both housings 22 and 2.
8 and fixed by suitable fixing means. The connecting member 32 is formed of a metal pipe such as steel or aluminum, and covers and protects the rack shaft 7 therein, and also serves as a strength member that integrally connects both housings 22 and 28 to provide strength. .

The connecting member 32 is press-fitted into the openings of both housings 22, 28 and then fixed to both housings by caulking. The connection member 32 may be attached to the housing 22.28 by mechanical connection, for example, as shown in FIGS. 4 and 5, but is not limited to this method.

In the example shown in FIG. 4, a connecting member 32a is used which is cylindrical and has a male thread formed on the outer periphery of one end and a flange extending radially outward at the other end. The male thread part is the housing 28
After the flange at the other end is screwed into the female threaded part 28b formed in the opening of the housing 22,
It is fixed and held by a fixing device such as a bolt 41 through holes that are in contact with each other and coincide with each other.

Thereafter, the connecting member 32a and the housing 28 are securely fixed by welding 40.

Furthermore, as shown in FIG.
It is also possible to make it contact with and fix it with a fixing device such as a bolt 41.

By appropriately adjusting the axial lengths of the connecting members 32, 32a, 3'2b as described above, the distance between the two housings 22 and 28 can be freely adjusted. Furthermore, the connecting member 32.3
If the cross sections of 2 a and 32 b are circular, a degree of freedom around the axis is provided, and the relationship between the housings 22 and 28 around the axis can be freely adjusted.

A reduction gear 24 is fitted into the nut member 25 within a housing 28 so that the nut member 25 rotates together. The reduction gear 24 is a gear having teeth on its outer periphery, and these outer periphery teeth mesh with the outer periphery teeth of the pinion gear 23 . The pinion gear ``1'' 723 is fixed on the shaft of a clutch 9 that takes out the output from the electric motor 8 whose shaft is arranged parallel to the rack shaft 7.
5.

Therefore, the rotational output of the electric motor 8 is transmitted from the pinion gear 23 to the reduction gear 24 via the clutch 9, and then to the nut member 25, thereby driving the nut member 25 to rotate. The rotation of the nut member 25 is transmitted to the worm 29 via the ball 33, thereby linearly displacing the rack @7 in the axial direction.

The electric motor 8 is arranged and fixed in a different housing outside the housing 28, and only its shaft is inserted into the housing 28 and engaged with the clutch 9. Therefore, the electric motor 8 from large capacity to small capacity can be used. Can be set. Furthermore, as shown in FIGS. 2 and 3, the electric motor 8 can be set at any position around the rack shaft 7. Further, the axis of the electric motor 8 does not need to be parallel to the rack axis 7, and can be freely set.

In this embodiment, the power of the electric motor 8 is supplied to the clutch 9.
It is transmitted to the ball screw appropriately using
It is also possible to directly input and output the power of the electric motor 8 to the ball screw via only the reduction gear without using the clutch 9.

The control circuit 11 switches between manual steering and power steering by appropriately turning on and off the clutch 9, and controls the electric motor 8 so as to obtain an appropriate output according to the torque and vehicle speed detected during power steering. do.

For example, when driving at low speeds, including when the steering force is heaviest, the electric motor 8 is controlled so as to engage the clutch 9 to obtain an output corresponding to the detected torque, and this output is applied to the steering wheel 1 for steering. so that the force is reduced,
When the steering force is still light and a more direct steering feeling is required, such as when driving at high speeds, the clutch 9 is disengaged for manual steering, or when power steering is required, the electric motor 8 is used, taking into account the vehicle speed, steering angle, etc. It is also possible to control the output of

In addition, in order to ensure failsafe, the clutch 9 is connected to the control circuit 11 so that manual steering is always performed when an abnormality occurs.
It is necessary to cut it.

The operation of the electric power steering device having the above configuration will be explained below.

When the clutch is not in operation, the output shaft of the electric motor 8 and the shaft of the pinion gear 23 of the reduction gear are separated. When the handle 1 is operated in this state, the rotation is converted into an axial movement of the rack shaft 7 by the engagement of the pinion gear part 16 and the rack gear part 17, and the steering wheel is moved through a ball joint and a knuckle arm (not shown). Decide on the direction.

This operation is a common manual rack-and-pinion steering system.

It's the same.

When the clutch 9 is in an operating state, the output shaft of the electric motor 8 and the shaft of the pinion gear 23 of the reduction gear are coupled. When the handle 1 is operated in this state, information regarding the handle shaft torque corresponding to the external load applied to the rack shaft 7 is detected by the input torque detector and transmitted to the control circuit 11. Information regarding the vehicle speed obtained from the vehicle speed detector 13 is also transmitted to the control circuit 11, and based on this information, the output of the electric motor 8 is controlled according to predetermined characteristics, and this output is transmitted to the pinion gear 23, reduction gear 24, and ball screw. It is transmitted to the rack shaft 7 with high efficiency and a large reduction ratio through the nut member 25, worm 29, and ball 33 that constitute the.

As described above, the rack shaft 7 is linearly displaced with the power assistance of the electric motor 8.

Although the preferred embodiments of the present invention have been described in detail above, other applications and modifications are possible.

For example, although we have shown an example in which a ball screw is used as a mechanism for transmitting the power of an electric motor to a rack shaft, instead of this, the output of the electric motor can be transmitted via a male and female screw that constitutes a general screw mechanism such as an acme screw. It may also be communicated.

Further, although the electric motor is arranged on the axis parallel to the rack axis, it is also possible to arrange it coaxially with the rack axis as shown in the third embodiment below.

FIG. 6 shows a third embodiment of the present invention, in which the same parts are given the same reference numerals and their explanation will be omitted.

In FIG. 6, the rack and pinion section 20 is connected to the housing 2.
A ball screw portion 30 provided on the same rack shaft 7 is provided inside the housing 28d. Rack and pinion part 20 and ball screw part 30
A clutch 9, an electric motor 8, and a connecting member 32d are arranged and connected to each other between them.

A clutch 9 is connected to the rack gear 17 side of the housing 28d in which the ball screw portion 30 is installed, and the electric motor 8 is connected to the clutch 9. The electric motor 8 and the housing 22 are connected by a connecting member 32d, so that each unit is integrally connected.

A member having a massing plate 37 is integrally attached to the nut 25 via a leaf spring 34, and when the electromagnetic coil 35 is ON, this massing plate 37 resists the force of the leaf spring 34 and is attached to the other massing plate 36. The nut 25 is connected to a motor output shaft 38 which is spline-coupled to a member having a mass plate 36 and which is engaged with the nut 25. When the coil 35 is OF”F, the mass plate 3
7 is drawn toward the nut 25 by the leaf spring 34, the two mass plates 36 and 37 are separated, and the output of the electric motor 8 is not transmitted to the nut 25.

(Effects of the Invention) The electric power steering device of the present invention has a structure in which the rack and pinion part and the power auxiliary part for transmitting auxiliary power are each unitized and the two parts are connected by a connecting means. Since the units can be manufactured and arranged individually, it is easy to install them in a vehicle, and it is also possible to easily accommodate differences and changes in vehicle specifications, as well as changes in design.

[Brief explanation of drawings]

Fig. 1 is an overall view of one embodiment of the present invention, Fig. 2 is a partial sectional view of the first embodiment shown in Fig. 1, and Fig. 3 is a partial sectional view showing a second embodiment of the invention. , 4 and 5 are sectional views showing second and third examples of the method of connecting the connecting member' and the housing, and FIG. 6 is a partial sectional view of a third embodiment of the present invention. (Explanation of symbols of main parts) 6・・・・・・・・・・・・Pinion shaft 16...
......Pinion gear part 7...
......Rack axis 17...
・Rack gear part 22.28...Housing

Claims (1)

[Claims] 1. A rotating shaft means directly driven by a handle;
a housing, an elongated member provided to linearly reciprocate within the housing and for steering a steering wheel, a rack formed on the elongated member, and a rack formed on the elongated member within the first housing. a first unit comprising: a pinion gear engaged with and fixed to the rotating shaft means; a screw means formed on a portion of the elongated member; and a nut means covering at least a portion of the screw means; , a ball screw means comprising a ball disposed between the screw means and the nut means, a second housing enclosing the ball screw means, an electric motor, and a second housing that engages with the nut means and the electric motor. a second unit comprising a power transmission means for transmitting the rotational output of the electric motor to the nut means; a connecting means for connecting the first unit and the second unit; a means for detecting the torque applied to the rotating shaft means. An electric power steering device comprising; and means for controlling an electric motor in response to the detection means. 2. The electric power steering device according to claim 1, wherein the electric motor is fixed to a third housing separate from the second housing to form a third unit. 3. The electric power steering device according to claim 1, wherein the electric motor is disposed coaxially with the elongated member within the second housing. 4. The electric power steering device according to any one of claims 1 to 3, wherein the connecting means is a metal pipe. 5. The electric power steering device according to claim 4, wherein the metal pipe is press-fitted into the first and second housings and then fixed by caulking. 6. The connecting means includes a cylindrical portion that covers the rack, a male threaded portion provided at one end of the cylindrical portion, and a flange portion provided at the other end, and the male threaded portion is connected to the first or second housing. The flange portion is screwed into a female threaded portion provided on one side, and the flange portion abuts on a corresponding flange provided on the other side of the first or second housing, and is mechanically fixed by a fixing device. An electric power steering device according to any one of claims 1 to 3.