JPH066433B2 - Torque detector electrical neutral adjuster - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrical neutral adjustment device for a torque detector of an electric power steering mechanism of an automobile or the like.

(Prior Art) In an electric power steering mechanism of an automobile or the like, a steering shaft is connected to a steering gear box through a torque detector, and torque applied to the steering shaft through a steering wheel is detected by the torque detector. In some cases, an auxiliary torque corresponding to the torque is additionally applied to the steering shaft by the electric motor to reduce the force for steering the steering wheel.

Examples of the torque detector include those shown in FIGS. 1 and 2. In FIG. 1, 1 is an input shaft connected to the output end of the steering shaft, and 2 is an output shaft connected to the steering gear box.

One end of the output shaft 2 is hollow, and the input shaft 1 is inserted and fitted in the hollow part. Further, the input shaft 1 is hollow so that the torsion bar 3 is
Is inserted into the inside of the output shaft 2. The input shaft 1 and the output shaft 2 have a pin 4a and a pin 4b, respectively.
Is connected to the torsion bar 3 by. Also, 5
Is an iron core, which is arranged around the fitting portion between the input shaft 1 and the output shaft 2, and is arranged in the circumferential direction as shown in FIGS. 1 and 2.
Four long holes 6a, 6b, 6c, 6 at positions separated by 0 °
and the pins 7a and 7c projecting to the outer periphery of the output shaft 2 are engaged with the long holes 6a and 6c, respectively.
Pins 7b and 7d protruding to the outer periphery of the input shaft 1 are engaged with 6d, respectively. Here, the long holes 6b and 6d are formed in a direction inclined by a required angle with respect to the axial direction, and the long holes 6a and 6c are formed in the axial direction. Also, input shaft 1
The periphery of the fitting portion between the output shaft 2 and the output shaft 2 is covered by the detector housing 7, and the input shaft 1 and the output shaft 2 are rotatably supported by bearings 8a and 8b provided on the inner wall of the detector housing 7. There is. Further, the bearing 8b is the output shaft 2
The detector housing 7 is fixed in the axial direction by being sandwiched by the ring 9 fitted to the outer periphery of the output shaft 2. On the other hand, a differential transformer 10 is fixed to the inner wall of the detector housing 7 around the iron core 5.

When the output shaft 2 is fixed and torque is applied to the input shaft 1 in the torque detector having the above-described structure, the torsion bar 3 is twisted and a rotation angle difference is generated between the input shaft 1 and the output shaft 2. At the same time, the pins 7b, 7 protruding from the input shaft 1
d is guided by the long holes 6b and 6d of the iron core 5, respectively, and the iron core 5 is displaced in the axial direction. With the axial displacement of the iron core 5, the output voltage of the differential transformer 10 changes, and the torque applied to the input shaft 1 is detected as an electric signal.

In the torque detector, during the assembling process, the iron core 5 with the torsion bar 3 coupled only to the output shaft 2 is used.
However, mechanical neutral adjustment is performed between the input shaft 1, the output shaft 2 and the iron core 5 so that the neutral position is in the movement range associated with the rotation angle difference between the input shaft 1 and the output shaft 2. Further, electrical neutral adjustment is performed so that the position of the iron core 5 with respect to the differential transformer 10 comes to a neutral position in a linear range where the output voltage of the differential transformer 10 linearly changes with respect to the axial displacement of the iron core 5. Must be broken. If the electrical neutral adjustment is not performed reliably, the output voltage characteristics with respect to the input torque of the torque detector will vary from one torque detector to another, and it will not be possible to ensure a predetermined performance.

In the electrical neutral adjustment, after the mechanical neutral adjustment is performed with the torque detector and the torsion bar 3 coupled only to the output shaft 2, the output shaft 2 is fixed and the iron core 5 is fixed to the input shaft 1.
Along with the axial movement from one end of the movable range to the other end, the output voltage of the differential transformer 10 at this time is measured by a voltage meter or the like, and from the measurement result, the output voltage is relative to the axial displacement of the iron core. Can be performed by determining a linear range that linearly changes, obtaining the neutral position of the range, and positioning the iron core 5 at the neutral position. However, when the electrical neutral adjustment work as described above is performed manually or visually, it is difficult to determine the linear range and the like, and it is inaccurate and erroneous adjustment is likely to occur. Furthermore, it takes a lot of time to adjust each torque detector, resulting in poor work efficiency.

(Problems to be Solved) The present invention eliminates such inconvenience, and
An object of the present invention is to provide a highly accurate and efficient electrical neutral adjusting device.

[Means for Solving the Problems] The present invention provides an input shaft connected to a steering shaft, an output shaft connected to a steering gear box,
The torsion bar, which is an elastic body connecting the both shafts, is engaged with the input shaft and the output shaft, and is displaced in the axial direction according to the relative rotation angle difference between the both shafts. Mechanically restricted, in a state where the torsion bar is connected to either of the shafts, an iron core axially movable with respect to one of the shafts and the other shaft; An electrical neutral adjustment device for a torque detector, which is arranged fixedly and has a differential transformer whose output voltage changes according to axial displacement of the iron core, wherein the device has a torsion bar, A shaft fixing means for fixing the one shaft in a state of being coupled to either the input shaft or the output shaft, an iron core moving means for moving the iron core in the axial direction by a pulse motor together with the other shaft, and the iron core moving means. Device for controlling the axial movement of the iron core through the means And a linear range detecting means for detecting the linear range in which the output voltage of the differential transformer linearly changes with respect to the axial displacement of the iron core, by the output potential difference per unit moving amount of the iron core. A first movement control means for axially moving the iron core from one end to the other end of the range including the linear range, and a linear range detection means for detecting the linear range in the moving process to detect the iron core in the linear range. Measuring means for measuring the movement amount D by the number of pulses of the pulse motor, calculation means for obtaining the movement amount D / 2 corresponding to the electric neutral position from the movement amount D, and displacement by D / 2 from one end of the linear range. Second movement control means for moving the iron core to the position.

(Operation of the Means) In the electric neutrality adjusting device, first, in a state where the torsion bar of the torque detector is connected to either the input shaft or the output shaft, the movable shaft is connected to the iron core moving means together with the iron core. Is fixed so that it cannot rotate, and the other shaft is fixed by the shaft fixing means.

Next, the pulse motor is rotationally driven by the first movement control means, and the iron core moves in the axial direction from one end to the other end of the range including the linear range. At this time, the linear range is detected by the linear range detecting means, the moving amount D of the iron core in the linear range is measured by the measuring means, and D / 2 is calculated by the calculating means. Next, the second movement control means moves the iron core to a position displaced by D / 2 from one end of the linear range, and the electrical neutral adjustment of the torque detector is performed.

(Embodiment) FIG. 3 shows a configuration in an embodiment of the electrical neutral adjustment of the present invention. The torque detector with electrical neutral adjustment in the device is shown in FIGS. 1 and 2. In FIG. 3, reference numeral 11 denotes a plate to which the torque detector 12 is fixed while the torsion bar 3 is connected only to the output shaft 2. The plate 11 is a slide table 15 which is movable in the axial direction of the torque detector 12 along a rail 14 on a base 13.
It is installed upright. Reference numeral 16 is a jig that is connected to the input shaft 1 of the torque detector 12 to fix the shaft 1 so as not to rotate. The jig 16 is the rail 1 on the slide table 15.
7 is installed upright on a slide table 18 which is movable in the axial direction of the input shaft 1. The slide table 18 is
Pulse motor 19 fixed to slide table 15
Drive shaft (not shown) is connected via a gear (not shown). On the other hand, on the output shaft 2 side of the torque detector 12, a jig 20 which is a shaft fixing means is erected on the base 13, and the slide table 15 is moved toward the jig 20 to The output shaft 2 is connected and the shaft 2 is fixed.

The slide table 18 is united together with the input shaft 1 and the iron core 5 toward the output shaft 2 side and the input shaft 1 side by the rotational drive of the pulse motor 19 at predetermined rotational angles of clockwise or counterclockwise, respectively. Moving. The rotational drive of the pulse motor 19 is controlled by a signal from a control device 21 electrically connected to the pulse motor 19 and the torque detector 12. Each pulse CW and CCW generated at a predetermined rotation angle when the pulse motor 19 is driven to rotate clockwise or counterclockwise is input to the control device 21 via a photocoupler (not shown). The output voltage of the differential transformer 10 of the torque detector 12 is input.

The control device 21 has a linear range detection means, a first movement control means, a measurement means, a calculation means, and a second movement control means, and the iron core 5 is controlled by controlling the rotational drive of the pulse motor 19 by the means. Controls the axial movement of the. Each of the above means will be described with reference to FIG. FIG. 4 shows changes in the output voltage V of the differential transformer 10 with respect to the axial displacement of the iron core 5 in the present embodiment. As can be seen from FIG. 4, the input shaft 1 side and the output shaft 2 side each have a range in which the output voltage V reaches the maximum V _MAX and the minimum V _MIN and is saturated. There is a linear range in which the voltage V changes linearly.

In the movement control of the iron core 5 by each of the above means, first, the pulse motor 19 is rotationally driven counterclockwise by the first movement control means, and from the position where the output voltage V is saturated on the input shaft 1 side to the output shaft 2 side. When the iron core 5 reaches a position where the output voltage V is minimized and reaches a saturation position by moving the iron core 5 by a unit amount toward, the output voltage difference ΔV _M per unit moving amount at that time is calculated. As will be described later, the linear range detecting means detects that the iron core 5 has reached the outside of the linear range, and the movement of the iron core 5 to the output shaft 2 side is stopped.

The linear range detecting means is set in advance in the linear range, and the output voltage difference ΔV _i (i = 1, 2, ..., M) per unit moving amount that is sequentially measured when the iron core 5 is moved by the unit amount. The voltage difference ΔV is compared, and ΔV _i <
When ΔV, it is detected that the iron core 5 has reached outside the linear range. On the other hand, in the moving process of the iron core 5 by the first movement control means, while the output voltage difference ΔV _i is ΔV _i ≧ ΔV, the iron core 5 is positioned within the linear range by the linear range detecting means. Is detected and the number of pulses of the pulse motor 19 is counted by the measuring means,
Number of pulses C corresponding to the moving amount D of the iron core 5 in the linear range
_D is measured. Further, by calculation means, C _N = C _D / 2
Is calculated and the number of pulses corresponding to the electrical neutral position is obtained. In this embodiment, the moving amount of the iron core 5 and the pulse number are 1
The number of pulses is used instead of the actual movement amount to correspond to the pair 1. When the pulse number C _N is obtained, the second
The pulse motor 19 is rotated clockwise by the movement control means, and the iron core 5 is moved by the pulse number C _N toward the input shaft 1 side from the final movement position by the first movement control means, so that the electrical neutrality is achieved. The iron core 5 is located at the position.

The circuit configuration of the control device 21 having the above means is shown in FIG. In the present embodiment, the circuit of the measuring means is included in the circuit of the computing means, and the circuit of the linear range detecting means is the same as the circuit of the first movement control means.

In FIG. 5, 22 is a circuit corresponding to the first movement control means and the linear range detecting means, 23 is a circuit corresponding to the measuring means, 24 is a circuit corresponding to the calculating means, and 25 is a second movement control. It is a circuit corresponding to the means. Further, the respective pulses CW and CCW when the pulse motor 19 is driven to rotate clockwise and counterclockwise are input to the circuits 25 and 24 via the photocouplers, respectively. Further, the output voltage V _i of the differential transformer 10 is input to the circuit 22.

The operation of the electrical neutrality adjusting device configured as described above will be described with reference to FIGS. 5 and 6.

First, in the linear range of the output voltage of the differential transformer 10, the output voltage difference ΔV per unit movement amount of the iron core 5 is set, and the count number of the pulse number is cleared. Next, as the first operation, the pulse motor 19 is driven counterclockwise, the iron core 5 is moved, and the output potential difference ΔV _i = | V _i −V _{i + 1} | per unit movement amount is measured for each unit movement. ,
When ΔV _i ≧ ΔV, counting of the number of pulses of the pulse CCW is started. The counting and the counterclockwise rotation driving of the pulse motor 19 are performed until ΔV _i <ΔV, and C _N = C _D / 2 is calculated from the counted total number of pulses D _D. In the first operation, the pulse number 19 is rotationally driven in the counterclockwise direction, and at the same time, the output voltage V _i of the differential transformer 10 before the iron core 5 makes a unit movement is changed by the signal of the timing controller in the circuit 22. A / D via buffer and sampling hold
It is converted, held in the first latch, and held in the second latch via the multiplexer. Then the output voltage V _{i + 1} after the iron core 5 has a unit movement is output to the subtracter via a multiplexer to the same manner as V _1, V _i the subtracter is held in the V _{i + 1} and the second latch And a difference ΔV _i is calculated and the calculation result is output to the first comparator. The above circuit operation is performed every time the iron core 5 is moved by the unit movement amount,
In the first comparator, Δ set as the reference data
V is compared with ΔV _i, and the counter signal is output when ΔV _i ≧ ΔV is first established, and the motor inversion drive signal is output when ΔV _i <ΔV is established thereafter. On the other hand, in the circuit 24, the first driver is driven by the line driver by the counter drive signal, and the pulse of which the pulse CCW passed through the photocoupler is doubled in frequency by the frequency divider is counted by the first counter. The count number is output to the second comparator. The count is
This is performed until the first comparator of the circuit 22 outputs the motor inversion signal. Since the first counter counts the pulse number of pulses obtained by doubling the cycle of the pulse CCW, the final output thereof is the pulse number C _N corresponding to the electrical neutral position.
= _CO / 2.

Next, as the second operation, the pulse motor 19 is driven to rotate clockwise by the motor inversion signal, and the number of pulses of the pulse CW is counted.
_When it becomes equal to _N , the rotational drive of the pulse motor 19 is stopped. In the second operation, in the circuit 25,
The pulse CW passed through the photocoupler is counted by the second counter driven by the line driver, and the counted number is output to the second comparator. The second comparator compares the final output _CN of the first counter with the output of the second counter, and outputs a motor stop signal when both are equal.

When the above-mentioned operation is completed, the torque detector 12 is brought into an electrically neutral state, and in this state, the input shaft 1 and the torsion bar 3 are coupled to each other to become an electrically neutrally adjusted torque detector.

In the present embodiment, the electrical neutral adjustment was performed with the torsion bar 3 coupled to the output shaft 2, but the torsion bar can be changed by changing the coupling relationship between the input shaft 1, the output shaft 2 and the torsion bar 3. It is also possible to make an electrical neutral adjustment with the 3 connected to the input shaft 1.

(Effects of the Invention) As is apparent from the above description, the present invention provides that the electrical neutral adjustment work of the torque detector is automated by the pulse motor and the control device, and the movement amount of the iron core depends on the pulse number of the pulse motor. Performing electrical neutral adjustment of the torque detector with high accuracy and in a short time by measuring and measuring the linear range of the output voltage of the differential transformer from the output voltage difference per unit movement of the iron core. It is effective to provide a device capable of

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a torque detector that is electrically neutrally adjusted by the electrical neutrality adjusting device of this embodiment, and FIG. 2 is
1 is a sectional view taken along the line AA of FIG. 1, FIG. 3 is a configuration diagram of an electrical neutrality adjusting device of the present embodiment, and FIG. 4 is a diagram for explaining control means of the control device of FIG. FIG. 5 is a circuit configuration diagram of the control device of FIG. 3, and FIG. 6 is a flow chart for explaining the operation of the electrical neutrality adjusting device of the present embodiment. DESCRIPTION OF SYMBOLS 1 ... Input shaft, 2 ... Output shaft, 3 ... Torsion bar, 5 ... Iron core, 10 ... Differential transformer, 12 ... Torque detector, 16, 18, 19 ... Shaft moving means, 19 ... Pulse motor, 20 ... Shaft Fixing means, 21 ... control device, 22 ... first movement control means, linear range detecting means, 23 ... measuring means, 24 ... computing means, 25 ... second movement control means,

Claims (1)

[Claims] 1. An input shaft connected to a steering shaft, and an output shaft connected to a steering gear box,
The torsion bar, which is an elastic body connecting the both shafts, is engaged with the input shaft and the output shaft, and is displaced in the axial direction according to the relative rotation angle difference between the both shafts. Mechanically restricted, in a state where the torsion bar is connected to either of the shafts, an iron core axially movable with respect to one of the shafts and the other shaft; An electrical neutral adjustment device for a torque detector, which is configured by a differential transformer whose output voltage changes according to axial displacement of the iron core, the torsion bar having an input shaft and an output shaft. In a state of being coupled to any of the above, a shaft fixing means for fixing the one shaft, an iron core moving means for moving the iron core in the axial direction by a pulse motor together with the other shaft, and the iron core moving means, It consists of a control device that controls the movement of the iron core in the axial direction. A linear range detecting means for detecting a linear range in which the output voltage of the differential transformer linearly changes with respect to the axial displacement of the iron core, based on a difference in output voltage per unit moving amount of the iron core; A first movement control means for axially moving the iron core from one end to the other end of the range including the range, and a linear range detection means for detecting a linear range in the moving process, and a moving amount D of the iron core in the linear range. Is measured by the pulse number of the pulse motor, and the moving amount D / 2 corresponding to the electric neutral position is calculated from the moving amount D.
And a second movement control means for moving the iron core to a position displaced by D / 2 from one end of the linear range.