JPH0611865Y2 - Electric power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an electric power steering apparatus, and more particularly to an electric power steering apparatus suitable for use in passenger cars.

[Conventional technology]

As for the conventional device, as disclosed in Japanese Patent Laid-Open No. 61-92960, it is considered to arrange an electric motor or a torque detector at an optimum position in order to reduce the size and weight of the auxiliary steering torque generating device.

It is also known that in this type of device, the output transistor is fixed to the gearbox and heat is radiated through the gearbox.

[Problems to be solved by the invention]

In the former case of the above-mentioned prior art, the control device for controlling the output of the electric motor is arranged so as to be fixed at a position away from the driving force generation device with a wiring cord, and the electromagnetic noise of the chopper device is prevented or the control device is It is not designed for downsizing, and the above problems cannot be solved.

Further, the latter does not mention that the heat dissipation of the semiconductor is performed more effectively.

It is an object of the present invention to provide an electric power steering device equipped with a motor output control device which is small and lightweight, has low electromagnetic noise, and has excellent heat dissipation.

[Means for solving problems]

The object of the present invention is to cover the output gear of the steering torque generating motor and the torque sensor for detecting the steering torque with a non-magnetic gear cover having a high heat radiation property, and to cover the outer surface of the cover with the power constituting the motor control circuit. This is achieved by fixing the module, and the gear cover is made of an aluminum material and has a thickness at least just below the semiconductor chip of the power module.

[Action]

Since the gear cover does not generate an attractive force against the electromagnetic force generated by the control device, it reduces electromagnetic noise and effectively dissipates the heat generated by the power module through the plate thickness portion directly below it, allowing the control circuit itself to be miniaturized. .

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. The steering wheel 1 transmits its steering force to the tire 4 via a rod 2 and a rack and pinion 3 which are steering shafts. As shown in FIG. 3, a torque sensor 5 and a gear 6 are provided below the rod 2 and are covered with a gear cover 7 made of aluminum. An electric motor 8 and a power module 9 are fixed around the gear cover 7, and the electric motor 8
The output shaft of is meshed with the gear 6 via a pinion gear 10. The power module 9 is an insulating case 1.
FET chip 12 and diode 13 arranged in 1
a, 13b, an insulating plate 14, a terminal block 15, and a base 16. Specifically, the outer periphery of the gear cover 7 is a flat surface and is fixed thereto by using screws or the like. In particular, the gear cover 7 at the portion corresponding to the mounting position of the semiconductor chip (FET chip 12, diodes 13a, 13b) of the power module is a thick plate and has a protruding portion 7a protruding inward.

In addition, 17 is a battery, 18 is a relay, and 19 is an electric motor control device.

Next, the control circuit of the electric motor will be described with reference to FIG.
The electric motor control device 19 controls the chopper circuits 13a and 13b of the chopper circuit 13 based on the signals from the torque sensor 5 or the vehicle speed sensor 51 and the electric motor current detector 71 so that a current flows through either of the field coils 20 and 21. Rotate the motor to the left or right.

The rotational force of the electric motor is controlled according to the vehicle speed, and is effectively given to the rod during stationary steering or low speed running,
Assists the operating force of the steering wheel.

FIG. 5 shows the characteristics of the energizing current I _M with respect to the torque sensor signal, but the larger the output of the vehicle speed sensor 51, the smaller I _M is.

According to the above-mentioned embodiment, the cooling fin of the power module is shared with the gear cover made of aluminum.
The power module of 0W class can reduce the weight of the cooling fin by about 2kg. In addition, by increasing the plate thickness of the gear cover immediately below the power module semiconductor chip, the short-time rating can be improved by about 10%, which is small, lightweight, and equipped with an electric motor output control device with less electromagnetic noise. A power steering device can be provided.

[Effect of device]

According to the present invention, the cooling fins of the power module can be shared with the gear cover, and the plate thickness of the gear cover immediately below the power module semiconductor chip is thickened, so that the control circuit itself can be downsized and electromagnetic noise is reduced. The electric power steering device may include the electric motor output control device.

[Brief description of drawings]

FIG. 1 is a schematic view of an electric power steering device of the present invention, FIG. 2 is a front view of the power module in FIG. 1, FIG. 3 is a side view of mounting the power module, and FIG. 4 is a motor control circuit diagram. FIG. 5 is a characteristic diagram showing an electric motor output characteristic with respect to a torque sensor signal. 1 ... Handle, 5 ... Torque sensor, 7 ... Gear cover, 8
... electric motor, 9 ... power module, 19 ... control circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masato Fukino 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Sadahiro Takahashi 2nd Takaracho, Kanagawa-ku, Yokohama, Nissan Car 56) Bibliographic references Sho 63-156867 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A non-magnetic material, which transmits the output of an electric motor controlled according to a steering torque to a steering shaft via a gear and has a high heat radiation property around the output gear and a torque sensor for detecting the steering torque. In the electric power steering device in which the power module constituting the motor control circuit is fixed to the outer peripheral surface of the gear cover, the gear cover is made of an aluminum material, and the thickness is provided directly below the semiconductor chip of the power module. An electric power steering device characterized by having it.