JPH0580386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an electric power steering device that uses a DC motor to assist the power of a steering device.

(Prior art) As a conventional electric power steering device, there is one shown in Figs. 5 and 6.
57-120164). That is, 100 is a rack shaft and 101 is a pinion shaft, which form a rack and pinion type steering device. A torque sensor 102 is attached to the pinion shaft 101 to detect the rotational direction and force of the pinion. Another pinion 103 on the rack shaft meshes with the same rack teeth that mesh with the aforementioned pinion, and this pinion 103 is connected to the servo motor 104.
and is connected by a connecting device 105. The servo motor is controlled and assisted by the output of the torque sensor 102 described above via a controller unit (not shown).

However, in such conventional electric power steering, a servomotor is used as the motor to control the rotation speed, etc., and therefore no other mechanical parts are required. Therefore, there is an advantage that the degree of freedom in motor arrangement is large and that the rack teeth can be shared.

However, the problem with servo motors is that the motor itself is very expensive, and the electronic control unit that controls it also requires a very complicated circuit, making it very expensive for electric power steering.

(Objective) The present invention aims to simplify the electronic control unit by using an inexpensive DC motor and powder clutch, and to provide the entire device in a compact and inexpensive manner.

(Structure) In order to achieve the above object, the present invention forms a steering device by meshing a first rack tooth formed on a rack shaft and a first pinion formed on a first pinion shaft, A sensor is provided between the pinion shaft and the steering wheel to detect the rotational direction and torque of the steering wheel, and the output of the sensor is supplied to the electronic control unit.
In a system in which the rotational torque of the steering wheel is reduced by a powder clutch via an operating DC motor and a speed reducer that decelerates the DC motor in response to a control signal from this unit, the powder clutch comprises: a worm shaft, the drive shaft of which is disposed around the outer periphery of the driven shaft, and which is fixed coaxially with the drive shaft of the D/C motor;
A worm wheel integrally fixed to the outer periphery of the drive shaft of the powder clutch is engaged with the powder clutch, and second rack teeth are formed on the rack shaft in parallel with the first rack teeth at positions substantially perpendicular to the circumferential direction. It is characterized in that the second pinion, which is fixed coaxially with the driven shaft of the powder clutch, is engaged with the lock teeth.

Hereinafter, a detailed description will be given based on examples. Reference numeral 1 denotes a handle pinion shaft, the upper part of which is attached to the handle column via a universal joint, and the first pinion 2 formed on the lower first pinion shaft meshing with the first rack tooth 3a on the side of the rack shaft 3. Both ends of the rack shaft 3 are connected to wheels via an inner ball joint assembly 4. 5 is a D/C motor arranged substantially parallel to the rack shaft 3. The D・
A worm shaft 6 fixed coaxially with the drive shaft of the C motor 5 meshes with a worm wheel 9 fixed integrally to the outer periphery of the drive shaft 8 of the powder clutch 7.

A second rack tooth 3b is formed on the rack shaft 3 in parallel with the first rack tooth 3a at a position substantially perpendicular to the circumferential direction, and a powder clutch 7 is formed on the second rack tooth 3b.
A second pinion 1 fixed coaxially with the driven shaft 10 of
1 is engaged. Reference numeral 12 denotes a clutch housing, which is formed integrally with the rack housing 13 and is fixed to the mounting collar 14 with bolts or the like. 15
A case houses a slip ring 16 for supplying current to the powder clutch 7, and is integrally molded with the clutch housing 12. 17 is a torque sensor attached to the handle column 18,
Generates output according to the direction of rotation of the handle and the load. Reference numeral 19 is an electronic controller that supplies current to the D/C motor 5 and powder clutch 7 according to the output.

Next, the effect will be explained. When the handle 20 is rotated, the torque sensor 17 installed on the handle column 18 generates an output according to the rotation direction of the handle 20 and the load. This output supplies current to the DC motor 5 and powder clutch 7 via the electronic controller 19 in accordance with the output. The D/C motor 5 starts rotating in the detected direction, and at the same time, the powder clutch 7 connects the driving shaft 8 and the driven shaft 10 by the magnetic force of the powder, and the D/C motor 5 starts rotating in the detected direction.
The rotation of the C motor 5 is transmitted to the driven shaft 10.
Since the second pinion 11 of the powder clutch is fixed to the driven shaft 10, the second pinion 11 of the powder clutch is fixed to the driven shaft 10.
The second pinion 11 of the powder clutch meshing with the lock teeth 3b also rotates, causing the rack shaft 3 to move in the axial direction. The powder clutch 7 easily transfers the assist force according to the load without transmitting more than necessary motor torque using the supplied current.
The power is transmitted to the electric power steering device, which functions as an electric power steering device.

(Effects) According to the present invention, the steering device is formed by meshing the first rack tooth formed on the rack shaft with the first pinion formed on the first pinion shaft,
A sensor is provided between the pinion shaft and the steering wheel to detect the rotational direction and torque of the steering wheel, and the output of the sensor is supplied to an electronic control unit, and the control signal from this unit operates the D/C motor. A powder clutch is used to reduce the rotational torque of the steering wheel via a reducer that reduces the speed of the D/C motor, and the powder clutch has its driving shaft disposed around the outer periphery of the driven shaft. , a worm shaft fixed coaxially with the drive shaft of the D/C motor and a worm wheel fixed integrally with the outer periphery of the drive shaft of the powder clutch are engaged with each other, and a second rack tooth is attached to the rack shaft. The second rack tooth is formed parallel to the first rack tooth at a position substantially perpendicular to the circumferential direction, and the second pinion, which is fixed coaxially with the driven shaft of the powder clutch, is engaged with the second rack tooth. By using a powder clutch, the electronic control unit can be simplified and the entire device can be provided compactly and at low cost. Further, second rack teeth are formed on the rack shaft in parallel with the first rack teeth at a position substantially perpendicular to the circumferential direction, and a second pinion fixed coaxially with the driven shaft of the powder clutch is meshed with the second rack teeth. Therefore, the main part of the electric power steering device can be constructed small and compact around the rack teeth, and
Since the preloads on the rack shaft on the first pinion shaft side and the second pinion shaft side are perpendicular to each other,
Compared to the conventional case in which preload is applied in the same direction, the unbalanced load on the rack shaft is reduced, and play between the pinion shaft and the rack shaft can be reliably eliminated.

[Brief explanation of the drawing]

Fig. 1 is a front view of an embodiment of the present invention, Fig. 2 is a partially cutaway plan view of Fig. 1, and Fig. 3 is an A-A in Fig. 2.
4 is a partially cutaway view of the handle column and an electric circuit, FIG. 5 is a front sectional view of the conventional device, and FIG. 6 is a planar sectional view thereof. DESCRIPTION OF SYMBOLS 1...Handle pinion shaft, 2...1st pinion, 3...Rack shaft, 3a...1st rack tooth, 3b
...Second rack tooth, 5...D/C motor, 6...Worm shaft, 7...Powder clutch, 8...Powder clutch drive shaft, 9...Worm wheel, 10...
Powder clutch driven shaft, 11...second pinion, 17...torque sensor, 19...electronic controller.

Claims (1)

[Claims] 1. A first rack tooth formed on a rack shaft, and a first rack tooth formed on a rack shaft.
A steering device is formed by meshing with a first pinion formed on a pinion shaft, and a sensor is provided between the pinion shaft and the steering wheel to detect the rotation direction and torque of the steering wheel, and the output of the sensor is A device that reduces the rotational torque of the steering wheel by supplying it to an electronic control unit and using a powder clutch through a DC motor that operates according to control signals from this unit and a reduction gear that decelerates the DC motor. In the powder clutch, the drive shaft thereof is disposed on the outer periphery of the driven shaft, and a worm shaft is fixed coaxially with the drive shaft of the D/C motor, and a worm shaft is disposed on the outer periphery of the drive shaft of the powder clutch. A worm wheel fixed thereto is engaged with the powder clutch, second rack teeth are formed on the rack shaft in parallel with the first rack teeth at a position substantially perpendicular to the circumferential direction, and a driven shaft of the powder clutch is formed on the second rack teeth. An electric power steering device characterized by engaging a second pinion coaxially fixed with a second pinion.