JPH0926043A - Electro-hydraulic stepping cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize opposition in regard to a large stroke and high speed response due to flow quantity change at an electric electro-hydraulic stepping cylinder. SOLUTION: The feed end discharge of pressure oil is changed over by driving rotatingly the inner rotor 12 of e rotary control valve 50 by means of a pulse motor 1, and by this, the straight line movement of the piston 4 of a differential cylinder 3 is carried out, and at the same time the feedback of the straight line movement of the piston 4 to the outer rotor 11 of the rotary control valve 50 is conducted. The rotary control valve 50 is fitted to the end of the differential cylinder 3, and reformation following capacity change is facilitated. The load of the pulse motor 1 is made to be the inertia load of the inner rotor 12 alone, and even if a large stroke is realized, high speed response is made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrohydraulic stepping cylinder using a three-way switching type rotary control valve used for hydraulic digital control.

[0002]

2. Description of the Related Art A conventional electrohydraulic stepping cylinder is shown in FIG. In the stepping cylinder of this example, the ball screw 2 is rotated by the pulse motor 1, and thereby the head of the piston 4 of the differential cylinder 3 (hereinafter referred to as the piston head).
The spool 5 installed in the 4a is slid along the axial direction of the ball screw 2, and the opening / closing direction of the pressure oil control port P and the pressure oil discharge port D provided on the piston head 4a is switched so that the piston 4 moves in the moving direction of the spool 5. The control is performed so as to follow. In FIG. 10, 4b is a rod of the piston 4 (hereinafter referred to as piston rod), A1 is a chamber on the left side of the piston head 4a, A2 is a chamber on the right side thereof, Ps is a supply pressure of pressure oil, Pout is a discharge pressure thereof, Pl Is the internal pressure of the right chamber A2.

That is, FIG. 1 in which the pulse motor 1 is rotated clockwise
In the state of 0 (A), the pressure oil in the chamber A2 on the right side is discharged from the pressure oil discharge port D to reduce the pressure, and the piston 4 moves to the right side in the figure. Further, in the state shown in FIG. 10B in which the pulse motor 1 is rotated counterclockwise, pressure oil is supplied from the pressure oil control port P to the right chamber A2 to increase the pressure, and the piston 4 moves to the left side in the drawing. For example, the spool 5 attached to the ball screw 2 is 10μ with one electric pulse given to the pulse motor 1.
When the reduction ratio and the lead angle of the ball screw 2 are set so that the pulse motor 1 moves by m and one pulse is applied to the pulse motor 1 to rotate the pulse motor 1 by a predetermined angle, the rotation of the ball screw 2 advances the spool 5 by 10 μm. The pressure in the chambers A1 and A2 on both sides of the piston head 4a is unbalanced and the piston 4 is driven. When the spool 5 and the ports P and D of the piston head 4a reach a position where they coincide with each other,
The pressures in the chambers A1 and A2 on both sides are balanced, and the piston 4 stops. In other words, the piston 4 will always follow the spool 5 attached to the ball screw 2,
The position of the piston 4 is statically guaranteed in proportion to the number of input pulses, and dynamically the piston 4 follows the spool 5 with a velocity deviation proportional to the frequency of the input pulse applied from the pulse motor 1.

[0004]

However, in the above-mentioned conventional electrohydraulic stepping cylinder, it is difficult to increase the moving speed of the piston 4 to enable high-speed response. That is, as is well known, in a hydraulic cylinder, V = Q / A is established between the speed V, the flow rate Q of pressure oil, and the area A of the cylinder.
Has to be increased, and in order to increase the flow rate Q, the area A of the cylinder has to be increased, and eventually the possible moving speed value is limited.

Further, in the conventional stepping cylinder, the load of the pulse motor 1 is the ball screw 2, and the entire ball screw 2 is rotationally driven by the pulse motor 1. Therefore, high speed response and large stroke are achieved. To achieve this, a pulse motor with a fairly large output was needed.

The present invention has been made in view of the above conventional problems, and it is possible to realize a high speed response by changing the flow rate, and a high speed response and a large stroke without using a large output pulse motor. An object is to provide an electro-hydraulic stepping cylinder.

[0007]

In order to achieve the above object, an electrohydraulic stepping cylinder according to the present invention changes the valve body position of a three-way control valve by rotational driving by a pulse motor to supply and discharge pressure oil. Is an electro-hydraulic stepping cylinder for controlling the reciprocating drive and operation of the piston rod of the differential cylinder by controlling
A casing having a hollow-cylindrical inner diameter and a pressure oil control port, a pressure oil inlet / outlet port, and a tank port located adjacent to each other, a pressure oil control port annular groove, a pressure oil inlet / outlet port annular groove, and Corresponding to a hollow cylindrical outer rotor that has an annular groove for a tank port at an outer peripheral surface position corresponding to each port of the casing and is slidably fitted into the casing, and the oil passage for pressure oil and the oil passage for tank. Switching annular groove provided at a position, a control annular groove provided at a position corresponding to the pressure oil inlet / outlet port annular groove, a connecting groove for connecting the switching annular groove and the control annular groove, and the connection A cylindrical inner having the same shape as the opening of the oil passage opening, and having the connecting oil passage opening and a land portion that divides the switching annular groove at an intermediate position between them, which is slidably fitted into the outer rotor. Rotor and body A three-way switching rotary control valve coaxially provided with shafts projecting outward from both rotors, wherein the three-way switching rotary control valve is attached to an end of the differential cylinder, and the piston rod Of the rotor shaft and one of the rotor shafts are connected to each other, and the other of the rotor shafts is connected to the pulse motor. The one shaft is rotated to control the supply and discharge of pressure oil to reciprocally drive the piston rod, and the one shaft connected to the feed screw by the rotation of the feed screw accompanying the reciprocal movement of the piston rod. And a configuration in which the rotor having the shaft is rotated.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a sectional view (A) showing an embodiment of an electrohydraulic stepping cylinder according to the present invention, and an assembled sectional view of a three-way switching type rotary control valve used in this embodiment, FIG.
Is a plan view of the present embodiment, FIG. 3 is a hydraulic circuit diagram thereof, and FIG. 4 is an exploded perspective view showing an outer rotor and an inner rotor that constitute a rotary control valve. It should be noted that in the following description, the elements common to the conventional ones will be described with the same reference numerals.

The stepping cylinder of this embodiment is mainly composed of
It consists of a pulse motor 1, a three-way switching type rotary control valve 50 and a differential cylinder 3, and the pulse motor 1 drives the rotary control valve 10 to switch between pressure oil supply and discharge, whereby the piston of the differential cylinder 3 is changed. 4 is moved linearly and the linear movement of the piston 4 is changed by the rotary control valve 5
The drive is controlled so as to feed back to 0.

First, the structure of the rotary control valve 50 will be described. The rotary control valve 50 is configured by rotatably fitting an outer rotor 11 in a casing 10 and rotatably fitting an inner rotor 12 in the outer rotor 11. The rotor 12 includes support shafts 13 and 14, respectively.
Support shaft 13 bolted to one end of the outer rotor 11
In this case, the cover 15a bolted to the casing 10 is penetrated to mechanically connect and fix the end portion of the ball screw 2,
The pulse motor 1 is connected to the support shaft 14 of the inner rotor 12 that projects outward from the cover 15b, and both shafts 13, 1
4 are supported by bearings 16 and 16 provided inside the covers 15a and 15b.

As shown in FIG. 1, the casing 10 also serves as a cylinder cover of the differential cylinder 3, has a hollow cylindrical portion 17 therein, and forms a pressure oil control port P, a tank port T and a control port C. is there. Pressure oil control port P
Is communicated with the chamber A1 of the differential cylinder 3 through an external pipe 51 arranged on the outer periphery of the differential cylinder 3, and the control port C is communicated with the chamber A2.

The outer rotor 11 is fitted to the inner peripheral surface of the hollow cylindrical portion 17 of the casing 10 with the outer peripheral surface in sliding contact with the outer peripheral surface.
Three annular grooves 20, 21, 22 are provided at positions corresponding to the ports P, T, C of the casing 10. Of these annular grooves 20, 21, 22 a pair of connecting oil passage openings 23, 23 penetrating into the hollow cylindrical portion 17 are formed in the pressure oil inlet / outlet port annular groove 21 so as to face each other in the radial direction. There is.
The pressure oil control port annular groove 20 and the tank port annular groove 22 are respectively provided with four pressure oil oil passage openings 24 and four tank oil passage openings 25. These oil passage openings 24 and 25 also penetrate into the hollow cylindrical portion 17. FIG. 6 is a development view of the inner surface of the outer rotor 11 showing these arrangements.

Further, the inner rotor 12 has a switching annular groove 26 provided at a position corresponding to the connecting oil passage ports 23, 23.
And the control annular grooves 27 and 28 which are provided at positions corresponding to the pressure oil control port annular groove 20 and the tank port annular groove 22 sandwiching this, and the switching annular groove 26 has a land surface. Are divided into four by four partition wall pins 29, which form a portion, and control groove portions 26a, 26 which are the divided portions.
b, 26c and 26d are alternately connected to the control annular grooves 27 and 28 by connecting grooves 30 and 31, respectively. FIG. 7 is a developed view of the outer surface of the inner rotor 12 showing these arrangements.

As shown in FIG. 8, the diameter W of the partition pin 29 is
1 is larger than the width W2 of the switching annular groove 26 and equal to the opening diameter of the connecting oil passage port 23 of the outer rotor 11. Therefore, the switching annular groove 26 and the connecting oil passage port 23
Between the outer rotor 11 and the inner rotor 12
Due to the relative rotation angle difference between and, an opening portion X having an area proportional to the angle difference is generated as shown in FIG. The partition pin 29 is made of, for example, a round bar material and has an annular groove 26 for switching.
And the top surface is cylindrically polished along the surface of the inner rotor 12, but other means may be used.

Further, the piston 4 of the differential cylinder 3 is provided with a cavity 52 extending from the piston head 4a to the middle of the piston rod 4b, and the piston head 4a portion of the cavity 52 is screwed into the ball screw 2 and fed. A nut 53 forming a screw means is fixed. Of course, the ball screw 2
It is not connected to the piston head 4a or the piston rod 4b except for screwing with the nut 53.

The operation of the electrohydraulic stepping cylinder configured as above will be described. First, the outer rotor 11
The inner peripheral surface side of the connecting oil passage port 23 is closed by the partition pin 29 of the inner rotor 12, and pressure oil from a hydraulic pressure source (not shown) is supplied to the pressure oil control port P and one chamber A1 of the differential cylinder 3. In this state, the inner rotor 12 is rotated by the pulse motor 1 by an angle corresponding to a predetermined number of pulses. Then, the connecting oil passage port 23 of the outer rotor 11 and the partition wall pin 29 of the inner rotor 12 are displaced from each other, and the connecting oil passage port 23 with respect to the control groove portions 26a, 26c of the inner rotor 12 as shown in FIG. Open.

The pressure oil supplied from the pressure oil control port P is the pressure oil control port annular groove 2 of the outer rotor 11.
0, through the pressure oil passage 24, into the control annular groove 27 of the inner rotor 12, and through the connecting groove 30 to the control groove portion 2
6a, 26c, from the connecting oil passage port 23 into the pressure oil inlet / outlet port annular groove 21 of the outer rotor 11, and supplied from the control port C to the other chamber A2 of the differential cylinder 3, whereby the differential The piston 4 of the cylinder 3 is driven so as to move leftward in the figure.

When the nut 53 moves along with the movement of the piston 4, the ball screw 2 screwed on the nut 53 rotates,
The linear motion of the piston 4 is converted into the rotary motion of the ball screw 2, and the outer rotor 11 mechanically connected to the ball screw 2 also rotates. That is, feedback according to the amount of movement of the piston 4 is applied to the outer rotor 11 via the support shaft 13, and the outer rotor 11 is
Follow the rotation of 2.

On the other hand, when the connecting oil passage opening 23 opens to the control groove portions 26b and 26d of the inner rotor 12 when the inner rotor 12 is rotated, the control groove portions 26a and 26c are connected to the connecting oil passage opening 23. Since it is blocked against, the pressure oil control port P and the control port C are cut off, and the control port C and the tank port T are in communication. That is, the other chamber A2 of the differential cylinder 3
The pressure oil returned from the pressure oil return port A is the pressure oil inlet / outlet port annular groove 21, the connection oil passage port 23, and the control groove portion 26.
b, 26d, the control annular groove 28, the tank oil passage opening 25, the tank port annular groove 22, and the tank port T through the connecting groove 31, and the fuel is discharged to the tank 54. Then, the pressure in the other chamber A2 of the differential cylinder 3 decreases, so that the piston 4 moves to the right in FIG. 3 due to the internal pressure of the one chamber A1. As a result, feedback is applied to the outer rotor 11 as before, and the outer rotor 11 follows the rotation of the inner rotor.

In such pressure oil supply and discharge operations, the rotational drive amount of the inner rotor 12 by the pulse motor 1 and the operation amount of the hydraulic actuator can be made to have a substantially linear relationship. That is, when the inner rotor 12 is rotated by one pulse, the connecting oil passage port 23 opens in the switching annular groove 26 in proportion to the rotation angle of the inner rotor 12, but the area of the opening X is the inner rotor. It can be easily formed so as to be linearly changed in accordance with the rotation amount of the outer rotor 12, and the outer rotor 11 follows the rotation of the inner rotor 12 and the partition pin 2
9 moves in a direction in which the opening portion X is closed with a predetermined delay to stop the supply and discharge of the pressure oil, the differential cylinder 3
Is driven to rotate by the pulse motor 1 by one pulse. In other words, the piston 4 is reciprocally driven by the relative angular difference between the outer rotor 11 and the inner rotor 12, and the outer rotor 11 is pressed by the rotation of the feed screw means including the ball screw 2 and the nut 53 so that the angular difference becomes zero. It is configured to distribute oil. Of course, contrary to the above description, the outer rotor 11
The same result can be obtained by setting the drive side to the drive side and the inner rotor 12 to the driven side.

In the present specification, all are described as a "pulse motor", but in this term, the rotation speed is controlled by receiving a pulse signal, and the rotation can be stopped at a rotation angle proportional to the number of input pulses. Includes all drive means.

[0022]

Since the electrohydraulic stepping cylinder according to the present invention is as described above, the valve distributing portion can be arranged at the end of the differential cylinder, and the large capacity and the small capacity can be easily recombined. In addition, the load of the pulse motor can be the inertial load of only the inner rotor, which is a rotating body. Therefore, even if the stroke of the differential cylinder increases, the load of the pulse motor does not increase. There is a great effect that a high speed response becomes possible.

[Brief description of drawings]

FIG. 1 is a sectional view (A) showing an embodiment of an electrohydraulic stepping cylinder according to the present invention, and an assembled sectional view (B) of a three-way switching type rotary control valve used in this embodiment.

2 is a plan view of the electro-hydraulic stepping cylinder of the embodiment of FIG.

FIG. 3 is a hydraulic circuit diagram of the same.

FIG. 4 is an exploded perspective view showing an outer rotor and an inner rotor that form a rotary control valve.

FIG. 5 is an operation explanatory diagram of the present embodiment.

FIG. 6 is a development view of a side wall surface of the outer rotor.

FIG. 7 is a development view of a side wall surface of the inner rotor.

FIG. 8 is a plan view showing a dimensional relationship between the switching annular groove and the partition pin.

FIG. 9 is a plan view showing an opening control state of an oil passage opening by a partition pin.

FIG. 10 is a sectional view showing the structure and operation of a conventional electrohydraulic stepping cylinder.

[Explanation of symbols]

 1 Pulse Motor 2 Ball Screw 3 Differential Cylinder 4 Piston 4a Piston Head 4b Piston Rod 10 Casing 11 Outer Rotor 12 Inner Rotor 13, 14 Support Shaft 17 Hollow Cylindrical Portion of Casing 20 Annular Groove for Pressure Oil Control Port 21 Pressure Oil Transfer Annular groove for port 22 Annular groove for tank port 23 Oil passage opening for connection 24 Oil passage opening for pressure oil 25 Oil passage opening for tank 26 Annular groove for switching 27, 28 Annular groove for control 29 Partition pin 30, 31 Connecting groove 50 Rotary control valve 51 External piping 52 Void in piston 53 Nuts A1, A2 Piston rod chamber P Pressure oil control port Ps Pressure oil supply pressure and chamber A1 internal pressure Pl Chamber A2 internal pressure T Tank port C Control port

Claims (1)

[Claims] 1. An electro-hydraulic stepping cylinder for controlling the supply and discharge of pressure oil by reciprocating and operating the piston rod of a differential cylinder by varying the valve position of a three-way control valve by rotationally driving a pulse motor. Wherein the three-way control valve is a hollow cylinder, has a lumen, and is adjacent to a casing having a pressure oil control port, a pressure oil inlet / outlet port, and a tank port, and an annular groove for the pressure oil control port. A hollow cylindrical outer rotor that has a pressure oil inlet / outlet port annular groove and a tank port annular groove at an outer peripheral surface position corresponding to each port of the casing, and is slidably fitted into the casing; Switching annular groove provided at a position corresponding to the oil passage opening for the tank and the oil passage opening for tank, a control annular groove provided at a position corresponding to the annular groove for the pressure oil inlet / outlet port, and the switching annular groove The outer shape having the same shape as the connecting groove for connecting the control annular groove and the opening shape of the connecting oil passage opening, and having the land portion for dividing the connecting oil passage opening and the switching annular groove at an intermediate position therebetween. A cylindrical inner rotor slidably fitted in the rotor, and the two rotors are coaxially provided with shafts respectively projecting outward.
A directional switching type rotary control valve, wherein the three-way switching type rotary control valve is attached to an end portion of the differential cylinder, and feed screw means for converting reciprocating motion of the piston rod into rotary motion and a shaft of the rotor. One of them is connected, the other of the rotor shafts is connected to the pulse motor, and the one shaft is rotated in response to the rotation of the other shaft to control the supply and discharge of the pressure oil to The piston rod is reciprocally driven, and the one shaft connected to the feed screw and the rotor having the shaft are rotated by the rotation of the feed screw accompanying the reciprocating movement of the piston rod. Electric hydraulic stepping cylinder.