JP2541671B2 - Rotary positioning device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary positioning device that automatically positions a torsion bar of a power steering and a valve shaft in a rotational direction.

(Prior Art) FIGS. 6 (A) and 6 (B) are views showing an example of the power steering, in which the pinion 11 is provided in the front housing 10a.
Is rotatably mounted, and the pinion 11 meshes with a rack 12 connected to wheels (not shown). A hollow valve body 13 is housed in a rear housing 10b that is integral with the front housing 10a and constitutes the housing 10. The valve body 13 is connected to the pinion 11 by a pin 14.

A tip end portion of a torsion bar 15 is press-fitted and fixed to a rear end portion of the pinion 11, and a valve shaft 16 is incorporated between the torsion bar 15 and the valve body 13. The valve shaft 16 has its rear end fixed to the rear end of the torsion bar 15 by a pin 17. The torsion bar 15 is connected to a steering wheel 18 as shown in FIG. 6 (A),
By the steering rotation of the wheel 18, the torsion bar 15
Since the rack 12 slides in the axial direction via the pinion 11, the wheels are steered.

In order to assist the steering force applied to the steering wheel 18, the pressure oil discharge portion 21 of the hydraulic pump 20 driven by the engine is provided in the inflow port 2 formed in the rear housing 10b.
Connected to two. As shown in FIG. 6 (A), the inflow port 22 communicates with an annular groove 23 formed in the valve body 13, and the annular groove 23 has three inflow ports formed in the valve body 13. Through the side communication hole 24 and the three outflow side communication holes 25 formed in the valve shaft 16,
It communicates with the oil chamber 26 in the valve shaft 16. An outlet port 27 is formed in the rear housing 10b, and the oil chamber 26
The pressure oil inside is the other communication hole 28 formed in the valve shaft 16.
And returns to the tank 29 via the outflow port 27.

As shown in FIG. 6 (B), the outflow side communication hole 25 is continuous with the secondary valve port groove 32, and the secondary valve port groove 32 is 120 ° with respect to the axial center. The phases are out of phase, and the primary valve port 31 is formed on the valve shaft 16 by shifting the phase by 60 ° with respect to these secondary valve port grooves 32. Six spool portions 33 are formed between the valve port grooves 31, 32 in the circumferential direction. In the valve body 13, right cutting land portions 34a and left cutting land portions 34b are alternately formed in the circumferential direction. The right cutting land portion 34a is connected to the right port 37a of the power cylinder 37 by the oil passage 35, and the left cutting land portion 34b is connected.
Is connected to the left port 37b of the power cylinder 37 by an oil passage 36. A piston 38 integrated with the rack 12 is provided in the power cylinder 37. In FIG. 6 (B), reference numeral 39 indicates a tire connected to the rack 12.

FIG. 6 (B) shows the relative positions in the rotational direction of the valve shaft 16 and the valve body 13 when the vehicle is set to the straight running state. At this time, the circumferential end portions of the respective spool portions 33 are shown. The pressure oil from the pump 20 returns to the tank 29 through the throttle portion 40 formed by the land portion 34a, 34b and the land portion 34a, 34b, the pressure oil does not become congested inside, the power cylinder 37 is operated. do not do.

Then, for example, the steering wheel (handle)
Assuming that the steering wheel 18 is rotated to the left, the rotation causes the tonton bar 15 to rotate to the left to move the rack 12 axially via the pinion 11 as well as to rotate the torsion bar 15
The valve shaft 16
It rotates relative to 13 to the left. As a result, pressure oil is congested in the valve, and the left port 37
As a result, the steering force is assisted by the power cylinder 37.

(Problems to be Solved by the Invention) To assemble such a power steering, when the steering wheel 18 is set to the neutral position, the valve shaft 16 is shown with respect to the valve body 13 in FIG. 6 (B). It is necessary to set these positional relationships so as to obtain such a predetermined neutral position.

For this purpose, the valve shaft 16
The positional relationship between the valve body 13 and the valve body 13 is set to a predetermined neutral position.
The displacement angle with respect to the neutral position was obtained from the relationship between the torque required for the rotation of the pump and the hydraulic pressure at the discharge portion of the pump 20. However, when obtaining this angle, conventionally, the estimated value was used as the spring constant of the torsion bar 15, so if the spring constant actually differs for each torsion bar 15, the neutral position is set accurately. However, the process of readjustment and the like later becomes unavoidable, and the power steering could not be assembled efficiently.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to enable the valve shaft to be automatically corrected to a neutral position with high accuracy.

(Means for Solving the Problem) The present invention for achieving the above-described object is to provide a rotation means for twisting and rotating only a valve shaft or a torsion bar integrally with the valve shaft, and torque detection for measuring torque of twisting rotation. Means and an angle detection means for detecting a torsional rotation angle of torsional rotation, wherein the valve shaft and the torsion bar are a rotary positioning device of a power steering for positioning the valve shaft at a neutral position in a rotational direction with respect to the torsion bar. From the torque measured and the detected rotation angle when twisting and rotating in the left and right directions, K = (TA-TB)
/ ([Theta] A- [theta] B) The spring constant calculation means for calculating the spring constant of the torsion bar, and the spring constant calculation means calculates the spring constant of the torsion bar, and then the valve shaft and the torsion bar. And
Calculated by the spring constant calculating means and the value of the torque measured when the oil pressure in the hydraulic passage for driving provided in the valve shaft becomes the predetermined reference pressure by twisting and rotating in the left and right directions as one unit again. From the above-mentioned spring constant of the torsion bar, Δθ = (T1-T2) · (1/2)
・ Having a deviation angle calculation means for calculating a deviation angle between the torsion bar and the valve shaft with respect to the neutral position represented by (1 / K), and using the valve shaft for the calculated deviation angle It is a rotary positioning device that rotates the torsion bar and adjusts it to the neutral position.

(Operation) In the present invention, first, the torsion bar incorporated in the power steering is torsionally rotated to the left and right, the respective rotation angles and the rotation torque required to rotate to that angle are obtained, and these are calculated. The actual spring constant of the torsion bar is automatically calculated from the value. After that, the torsion bar is twisted and rotated again to the left and right to obtain the rotational torque value when the hydraulic pressure in the hydraulic passage becomes the reference pressure,
The deviation angle between the torsion bar and the valve shaft with respect to the neutral position is calculated using these torque values and the already-measured actual values of the spring constants. Then, the valve shaft is rotated by the displacement angle to rotationally position the valve shaft at the neutral position.

(Embodiment) FIG. 1 is a view showing an embodiment of the rotary positioning device of the present invention, in which the valve shaft 16 and the valve body 13 of the power steering shown in FIGS. 6 (A) and 6 (B) are predetermined. The present invention has been embodied for rotationally positioning to a neutral position.

In FIG. 1, only a part of the above-described power steering such as a torsion bar is shown, and the other parts are omitted. This power steering is preassembled as shown in FIG. 6 except that the pin 17, that is, the pin for fastening the torsion bar 15 and the valve shaft 16 is not fixed. The part is fixed to a base (not shown) by a fastener 45.

Above the fastener 45, a chuck 46 is rotatably attached to a fixed base 48 via a universal joint 47. In order to rotate the chuck 46, a servo motor 50 is attached to the mount 48, and the chuck 46 is rotated by the motor 50 via the speed reducer 51. The chuck 46 includes a torsion bar chuck 46a for fastening the end of the torsion bar 15 and a valve shaft 1.
It has a valve shaft chuck 46b for fastening the ends of 6, and these are integrated. The chuck 46
As shown in FIG. 1, two electromagnetic brakes 52a and 52b, that is, first and second electromagnetic brakes, are incorporated in this. First electromagnetic brake 52
a is for locking both chucks 46a, 46b to each other and mechanically connecting them. Further, the second electromagnetic brake 52b is for locking only the torsion bar chuck 46b to the fixed bar member 49 integrated with the fixed base 48 to prevent the torsion bar 15 from rotating. Sometimes the other chuck 46a
Is ready for rotation by the motor 50.

Further, as shown in FIG. 1, an encoder 53 is attached to the servo motor 50 in order to detect the rotation angle of the servo motor 50, and in order to detect the protrusion pressure from the hydraulic pump 20, the hydraulic pump 20 Pressure sensor on the protruding end of
54 is provided with a universal joint 47 and a chuck 46.
A torque tensor 55 for detecting a rotational torque required for torsional rotation is provided on a shaft portion connecting the and.

FIG. 2 is a diagram showing a control circuit for controlling the operation of these components, the encoder 53 and the torque sensor.
The output signals from 55 and pressure sensor 54 are AD converter 56
Then, the analog signal is converted into a digital signal and input to the microcomputer CPU57. A control signal is sent from the CPU 57 to the chucks 46a and 46b and the first and second electromagnetic brakes 52a and 52b, respectively, and the servomotor 50 is connected to the CPU 57.

Next, a procedure for adjusting the torsion bar 15 and the valve shaft 16 to the neutral position using the above-mentioned device will be described with reference to the flowchart shown in FIG.

First, the power steering, which is a work, is positioned at the position of the fastener 45 by the transport device (not shown), and when it is determined in step 60 that the work has been fastened, the chuck 46a for the torsion bar and the valve in step 61. The chucks 46b for the shaft are actuated and fastened by these chucks, and the chucks 46a and 46b are brought into a connected state by the first electromagnetic brake 52a. Then, in step 62, the hydraulic pump 20 is driven. Then, in step 63, the spring constant K of the torsion bar 15 is calculated.

The spring constant K (Kg · cm / deg) is obtained by obtaining TA, TB, θA, θB and calculating the value of (TA−TB) / (θA−θB). In other words, when the torsion bar 15 and the valve shaft 16 are integrally fastened by the chucks 46 and 47 and they are rotated in the left-right direction, the rotation angle θA is obtained by the encoder 53 when rotated in the right direction, The torque sensor 55 determines the torque value TA at that time. Similarly, TB and θB when rotated to the left are obtained. In Figure 4, the torsion bar 1
5 is a characteristic diagram showing the relationship between the torque T required to twist 5 and the measured pressure P of the pressure sensor 54 at each torque, and the measured values of the pressure sensor 54 when rotated to TA and TB at the respective angles. Is assumed to be PA and PB in FIG. 4 (A). As shown in FIG. 4 (A), the torsion angle of the torsion bar has a constant relationship with its torque value.

From the above measurements, the actual spring constant of the installed power steering torsion bar 15 is stepped.
Calculated as 63.

When it is determined that the calculation has ended, next, in step 64, the angle deviation amount Δθ (deg) is calculated. To calculate this, the torsion bar 15 and the valve shaft 16 are rotated to the right by the motor 50 to obtain the torque value T1 when the pressure sensor 54 detects a predetermined reference pressure value P0, and the left direction is calculated. The torque T2 at the time when this reference pressure value P0 is reached is obtained by rotating to. And (T1 + T2)
The deviation angle Δθ (deg) is calculated by obtaining the value of (1/2) · (1 / K).

The value of the deviation angle amount Δθ (deg) is stored in a storage medium such as the CPU 57, and then step 65 is executed. In this step, the first electromagnetic brake 52a is released and the second electromagnetic brake 52a is released.
The electromagnetic brake 52b is set to the activated state. As a result, the torsion bar 15 is locked to the fixed base 49, and only the valve shaft 16 is set in a rotatable state. Next, the servo motor 50 is rotated, and only the valve shaft 16 is rotationally driven in step 66. This rotation angle is set to the angle of Δθ already measured.

Further, step 67 is executed to execute the first electromagnetic brake 52.
a is activated, and the second electromagnetic brake 52b is released. This allows the torsion bar 15 and valve shaft
16 and 16 can rotate together.

In this state, as shown in FIG. 4 (B), the hydraulic pump
The torque value when the discharge pressure from 20 becomes the reference value P0,
By driving the motor 50, the value T1 when the torsion bar 15 and the valve shaft 16 are rotated to the right and the value T2 when they are rotated to the left are respectively detected (step 6).
8). Next, at step 69, these torque values T1 and T2 are added, and the value is divided by 2 to calculate the torque deviation amount ΔT. Then, in step 70, it is determined whether or not the absolute value of the deviation amount ΔT is smaller than the absolute value of the torque value T0 at the neutral position.

Here, as shown in FIG. 4 (B), if the torque value is equal to or less than the predetermined torque value, the neutral position setting operation ends, and the pin position is set.
Although the driving operation of 17 is performed, if the torque value is equal to or less than the predetermined torque value, the process returns to step 63 again and the above-described processing is executed again.

As described above, in the present invention, whether or not the torsion bar 15 and the valve shaft 16 are in the neutral position is detected after detecting the spring constant of the tone bar 15 in each power steering. ing.

On the other hand, conventionally, as described above, the spring constant of each torsion bar 15 is a predetermined value set in advance.
The deviation was adjusted assuming K0. Fifth
The figure is a diagram showing a conventional method of adjusting the deviation amount, the torque value when the pressure sensor 54 reaches the reference pressure P0 is obtained for the right rotation T1 and the left rotation T2, and the torque deviation amount ΔT is obtained from these values. Then, the reciprocal of the spring constant K0 is added to this to calculate the angle deviation amount Δθ. Therefore, even if the valve shaft is displaced by the calculated shift amount, if the spring constants of the torsion bars 15 in the respective power steerings vary, the corrected neutral position will vary. For example, as shown in FIG. 5 (B), it may not be possible to accurately adjust the neutral position after the correction. On the other hand, in the present invention, since the spring constant of each torsion bar is automatically calculated, it is possible to set the neutral position with high accuracy. The present invention is not limited to the power steering of the illustrated type as long as it is a type of power steering having a torsion bar, and can be applied to various types.

(Effects of the Invention) As described above, according to the present invention, the torsion bar when the torsion bar incorporated in the power steering is twisted and rotated in both the left and right directions, and the rotational torque required for this are automatically determined. The actual spring constant of the torsion bar is calculated, and then the rotational torque value when it becomes the reference pressure is detected when it is twisted again in both left and right directions. From this, it is determined how much the valve shaft deviates from the neutral position, and the amount of deviation is corrected.
Therefore, even if the actual spring constant of the built-in torsion bar varies with respect to the set value, it is possible to position the valve shaft in the neutral position with high accuracy, which makes it suitable for various types of power steering. Can be applied.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a rotary positioning device of the present invention,
FIG. 2 is a block diagram showing a control circuit of the present invention, FIG. 3 is a flow chart showing an operating procedure of the present invention, and FIG. 4 (A).
(B) is a graph showing a torque characteristic curve when each deviation is adjusted, FIGS. 5 (A) and (B) are graphs showing a torque characteristic curve in a conventional deviation adjustment method, and FIG. 6 (A) is a power steering. Sectional view showing an example of No. 6,
FIG. 6B is a sectional view taken along the line BB in FIG. 10 …… Housing, 11 …… Pinion, 12 …… Rack, 13
...... Valve body, 15 ...... Torsion bar, 16 ...... Valve shaft, 20 ...... Hydraulic pump, 46a ...... Torsion bar chuck, 46b ...... Valve shaft chuck, 50
...... Servo motor, 52a …… First electromagnetic brake, 52b…
… Electric 2 electromagnetic brake, 53 …… Encoder, 54 …… Pressure sensor, 55 …… Torque sensor, 57 …… CPU (spring constant calculation means, deviation angle calculation means).

Claims (1)

(57) [Claims] Claim: What is claimed is: 1. A valve shaft alone, or a rotation means for twisting and rotating the valve shaft and the torsion bar as one body.
Rotational positioning device for power steering having torque detection means for measuring torque of torsional rotation and angle detection means for detecting torsional rotation angle of torsional rotation, and for positioning the valve shaft at a neutral position in a rotational direction with respect to the torsion bar. In the above, from the torque (TA, TB) measured when the valve shaft and the torsion bar are integrally twisted and rotated in both left and right directions and the detected rotation angle (θA, θB), K = (TA- After calculating the spring constant (K) of the torsion bar by the spring constant calculating means for calculating the spring constant (K) of the torsion bar represented by TB) / (θA−θB) , The valve shaft and the torsion bar are re-integrated, and are twisted and rotated in both left and right directions so that the valve shaft is The torque values (T1, T2) measured when the hydraulic pressure in the driven hydraulic passage reaches a predetermined reference pressure, and the spring constant (T1) of the torsion bar calculated by the spring constant calculating means ( K) and deviation angle calculation for calculating the deviation angle (Δθ) between the torsion bar and the valve shaft with respect to the neutral position represented by Δθ = (T1 + T2) · (1/2) · (1 / K) And a means for calculating the deviation angle (Δ
A rotary positioning device that adjusts to the neutral position by rotating the torsion bar by θ).