JPH0532742Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a torque detection mechanism for an electromagnetic booster using an electric motor that applies auxiliary torque to an output shaft.

(Prior Art) As an electric power steering device for automobiles, etc., there is a device equipped with an electromagnetic booster using an electric motor as a drive source, which was previously filed by the applicant of the present application. This electromagnetic booster uses a torsion bar to connect the input shaft and output shaft.
A torque detection mechanism is provided to detect steering torque applied to the input shaft through the steering wheel. This torque detection mechanism consists of a movable core that can be displaced in the axial direction according to the relative rotational angle difference between the input shaft and output shaft, and a differential transformer that is fixed to the steering column around the movable core. The steering torque applied to the steering wheel is detected as an electrical signal from the differential transformer based on the amount of displacement of the movable iron core.

Furthermore, the movable iron core is manufactured and assembled so that it is located at an electrically neutral position when the torque difference between the input and output shafts is zero, that is, when no steering torque is applied to the steering wheel.

Further, fine adjustment of assembly errors has been performed by zero point adjustment in a control circuit that processes electrical signals from the differential transformer.

(Problem that the invention aims to solve) However, in the above-mentioned torque detection mechanism, while the steering torque is detected by combining a detection mechanism unit and a control circuit, there is a problem that, since the detection mechanism unit and the control circuit are not compatible, when it becomes necessary to replace the control circuit, the detection mechanism unit must also be replaced, resulting in reduced maintainability.

Therefore, an object of the present invention is to provide a torque detection mechanism that has compatibility between the detection mechanism section and the control circuit and can improve maintainability.

(Means for Solving Problems and Effects) The torque detection mechanism of the present invention has a structure in which a steering column on which a differential transformer is fixed is attached movably in the axial direction with respect to the steering shaft. By moving and fixing the column in the axial direction and setting the movable iron core at an electrically neutral position with respect to the differential transformer, the zero point adjustment of the detection mechanism can be performed.

(Embodiment) A preferred embodiment of the present invention will be described below based on the accompanying drawings.

1 to 2 a, b, and c show the torque detection mechanism of the electromagnetic booster of this embodiment.

In the steering column 1, an input shaft 4 and an output shaft 7 are rotatably supported by bearings 2a, 2b, and 3. The bearings 2a, 2b are attached to the input shaft 4 so as to be movable in the axial direction. The input shaft 4 is divided into a first shaft 5 and a cylindrical second shaft 6, and a steering wheel is fixed to the outer end of the first shaft 5. Further, the first shaft 5 and the second shaft 6 are elastically connected by a rubber bushing for preventing vibration transmission. The input shaft 4 and the output shaft 7 are connected at their inner ends by a torsion bar, and the outer end of the output shaft 7 is connected to a gear of a steering gear box via a universal joint. Therefore, the input shaft 4 is controlled by the steering wheel.
The rotational torque applied to the torsion bar is transmitted to the output shaft 7 and the load side through the torsion of the torsion bar.
A steering speed sensor 8 is provided around the input shaft 4 . The steering speed sensor 8 includes a plurality of protrusions 9 protruding from the outer periphery of the second shaft 6 at equal intervals in the radial direction, and a photocoupler (photoelectric coupler) attached to the steering column 1 so as to sandwich the protrusions 9. 10, which receives the transmitted light that is interrupted by the protrusion 9, converts the received light into a pulsed electrical signal, and outputs it.

A torque detection mechanism 11 is provided around the connection portion between the input and output shafts 4 and 7. This steering torque sensor 11 is constructed by a differential transformer consisting of a cylindrical movable iron core 12 provided on the outer periphery of the input/output shaft connection part so as to be displaceable in the axial direction, and a coil part 13 fixed to the inner wall of the steering column 1. It is configured. The movable iron core 12 is connected to the output shaft 7 as shown in FIGS.
Elongated holes 16a and 1 engage with pins 14 protruding from each of the protruding pieces 7a, and pins 15 protruding from the second shaft 6 at an angle of 90° with respect to these pins 14, respectively.
6b. The elongated hole 16a is formed along the axial direction, while the elongated hole 16b is formed inclined at a predetermined angle with respect to the axial direction. Therefore, if an angle difference occurs between the input shaft 4 and the output shaft 7 in the circumferential direction, the elongated hole 16b, the pin 14 and the elongated hole 1
6a and the pin 15, the movable iron core 12
moves in the axial direction, and the movable iron core 12 is displaced in response to the steering torque applied to the input shaft 4.

Coil portion 13 provided around movable iron core 12
A primary coil 13a receives a pulse signal from a control circuit, and a pair of secondary coils 13b are coaxially disposed on both sides of the primary coil 13a and output an output signal corresponding to the displacement of the movable iron core 12. Consisting of Therefore, when an angular difference occurs between the input shaft 4 and the output shaft 7 due to twisting of the torsion bar, the axial displacement of the movable core 12 is converted into an electrical signal and output, and is processed in the control circuit. Ru.

Further, the steering column 1 to which the coil portion 13 is fixed is formed into a cylindrical shape whose inner end side fits into a steering column mounting portion 21a formed at an end of a stator 21 of an electric motor 20, which will be described later. A plurality of elongated holes 18 are provided in the circumferential direction, and each of these elongated holes 18 is formed along the axial direction. The steering column 1 is fixed to the stator 21 by screws 19 through these elongated holes 18, and the steering column mounting portion 21a of the stator 21, together with the bearings 2a and 2b, forms a support means that enables axial movement. . That is, the steering column 1 is attached to the steering shaft so as to be movable in the axial direction. Therefore, during manufacturing and assembly, the steering wheel is set at a neutral position so that no torque difference occurs between the input and output shafts, and the movable iron core 12 is set at an electrically neutral position with respect to the coil portion 13. By moving the steering column 1 in the axial direction through the elongated hole 18 and displacing the coil portion 13 relative to the movable core 12, the electrical neutral position of the movable core 12 can be finely adjusted. Furthermore, Figure 2a
In the figure, 24 indicates a torsion bar.

Further, an electric motor 20, a reduction gear 22, and an electromagnetic clutch 23 are arranged around the output shaft 7. The electric motor 20 has a stator 21 fixed to the steering column 1, and generates rotational torque corresponding to steering torque. When steering torque is applied to the input shaft 4, the torque is transmitted from the input shaft 4 to the output shaft 7 via the torsion bar. At the same time, the steering torque sensor 8 detects the direction and torque amount of the steering torque, and the steering speed sensor 8 further detects the magnitude and direction of the speed. These signals are processed in the control circuit and voltage is supplied to the electric motor 20. electric motor 20
The rotational torque is reduced by the reduction gear 22 and output to the output shaft 7 through the electromagnetic clutch 23.

(Effect of the invention) As is clear from the above explanation, according to the invention,
By attaching the steering column that fixes the differential transformer so that it can move in the axial direction, the electrical neutral position of the movable core can be mechanically finely adjusted. This makes it possible to have compatibility with the 2018-2010, improve maintainability, and reduce costs.

[Brief explanation of the drawing]

1 to 2c show an embodiment of the torque detection mechanism according to the present invention, in which FIG. 1 is a longitudinal sectional view thereof, FIG. Figures b and c are a plan view and a side view of the movable core. In the drawing, 1...steering column, 2a, 2
b...bearing (supporting means), 4, 7...steering shaft (input shaft, output shaft), 12...movable iron core, 13...differential transformer, 18, 19...elongated hole and screw, 20... ...elastic means (torsion bar),
21a... Steering column mounting portion (supporting means).

Claims (1)

[Scope of utility model registration request] A movable iron core that displaces in the axial direction in response to the relative rotational angle difference between the two shafts is provided around a connecting portion where the steering shaft, which is divided into two in the axial direction, is connected by an elastic means, and the steering shaft around this movable iron core is A differential transformer for detecting the axial displacement of the movable iron core is fixedly installed on the inner wall of the column, and a differential transformer is rotatably installed between the steering column and the steering shaft.
A torque detection mechanism for an electromagnetic booster, characterized in that a support means for supporting movement in the axial direction is provided.