JPH01188704A - Hydraulic servo cylinder - Google Patents

Abstract

PURPOSE:To construct the whole servo cylinder in a small size by feedbacking the moving volume of a piston to the valve body of a valve device via a screw shaft for feedback. CONSTITUTION:A nut 8 for feedback is provided at a piston 3, a screw shaft 9 is screw-engaged with the nut 8 and one end of the screw shaft 9 is connected to the shaft portion 39 of the driving poppet 16 of a valve device 6. Accordingly, the moving volume of the piston 3 is mechanically feedbacked to the valve body of the valve device so that the valve body of the valve device 6 is displaced temporarily and later it is usually returned to an original position. Accordingly, it is unnecessary to project the valve body long to cover the maximum moving area of the piston so that the whole servo cylinder 1 can be constructed is a small size.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fluid pressure servo cylinder that can be positioned arbitrarily.

[Prior Art] Conventionally, a hydraulic servo cylinder shown in FIG. 3 has been known as this type of position controllable fluid pressure cylinder (Japanese Utility Model Publication No. 81-38801).

This hydraulic servo cylinder includes a cylindrical actuating piston 63 integrally connected to one end of a piston rod 62 that protrudes from a cylinder 61 and serves as an output shaft, and this actuating piston 63.
It is equipped with a spool 64 provided inside the spool 64 and a feed screw 65 as an input transmission means for moving the spool 64 in the axial direction.The feed screw 65 is rotated by an input means such as an electric pulse motor or a DC servo motor. , by moving the spool 64, the relative position between the 1-actuating piston 63 and the spool 64 changes from the constant pressure chamber 67 to the variable pressure chamber 68.
The channel 69 for circulating pressure oil to the variable pressure chamber 68 and the channel 70 for circulating return oil from the variable pressure chamber 68 to the outside are opened and closed.
By changing the pressure of
It is configured to move following the movement of. In addition, 71 is a supply port for supplying pressure oil from a supply pressure oil source to the constant pressure chamber 67 in order to maintain the constant pressure chamber 67 at a predetermined pressure at all times;
Reference numeral 72 denotes a fluid discharge groove formed in the outer circumferential wall of the actuating piston 63 in a range larger than its stroke size.

According to this hydraulic servo cylinder, when the spool 64 is moved to make the pressure on the variable pressure chamber 68 side low, the pressure on the variable pressure chamber 68 side is lowered.
Return oil from the working piston 63 via the spool 64
The oil is guided to the fluid discharge groove 72 on the outer periphery of the working piston 63 through a flow path 70 inside, and is directly discharged to the outside through the discharge lower 4 on the side wall of the cylinder 61, so that the oil returns to the piston rod 62 and circulates. There is no need to form a flow path, and there is an advantage that the response speed of the actuating piston 63 can be improved by the amount of the flow path.

[Problems to be Solved by the Invention] However, the above servo cylinder has a constant pressure chamber 67 and a variable pressure chamber 6.
8 and the actuating piston 6 which receives pressure from each
For example, spool 6
4 moves to the left, the flow path 69 is opened, pressure oil flows from the constant pressure chamber 67 to the variable pressure chamber 68, the pressure in the variable pressure chamber 68 increases, and the actuating piston 63 expands from the constant pressure chamber 67 side to the effective area. When the large variable pressure chamber 68 receives a large pressure and moves to the left, blocking the flow path 69, the flow of pressure oil into the variable pressure chamber 68 is stopped. In other words, the operating principle of the servo cylinder is such that one side of the actuating piston 63 is always used as a constant pressure chamber 67, and only the other side is used as a variable pressure chamber 68, and the servo cylinder operates based on the differential pressure therebetween. Therefore,
Only a portion of the pressure of the pressure source is used for operating the servo cylinder, and as a result, a relatively high pressure source is required, which is disadvantageous in terms of responsiveness.

Further, the piston 62 and the feed screw 65 need to relatively protrude and move in and out by a length corresponding to the maximum movement range of the piston 62, and a valve chamber of a corresponding length is formed inside the piston 62, and the feed screw 65 It is necessary to make the feed screw 65 long so that it can be moved in and out of the piston 62.

The present invention has been made in view of the above problems.

By using both the empty chambers on both sides of the operating piston as variable pressure chambers, even if the fluid pressure source has a relatively low pressure, such as air pressure, the pressure of the pressure source can be used to the maximum to operate efficiently. It is an object of the present invention to provide a fluid pressure servo cylinder that can be used in a compact manner.

[Means for Solving the Problems] The present invention provides a piston having a piston rod provided in a cylinder and serving as an output shaft at one end, a first variable pressure chamber partitioned by the piston, and a second variable pressure chamber formed in the cylinder. It has a variable pressure chamber, a pilot screw shaft rotated by an electric motor, and a valve body that is sent in the axial direction by the rotation of the pilot screw shaft, and the axial displacement of the valve body creates the first and second variable pressure chambers. a valve device that connects one of the chambers to a fluid pressure outlet and the other to a fluid pressure supply port; the valve device is coupled to be movable in an axial direction with respect to a valve body of the valve device, and is threadedly engaged with the piston; When the piston moves due to a pressure difference between the first variable pressure chamber and the second variable pressure chamber due to the valve action of the valve device, the valve body of the valve device is rotated according to the amount of movement of the piston and returns to its original position. A feedback screw shaft is provided to constitute a fluid pressure servo cylinder.

[Action 1: When the pilot screw shaft is rotated by the electric motor,
The valve body of the valve device is moved axially to the left or right. Due to this axial displacement of the valve body, one of the first variable pressure chamber and the second variable pressure chamber is connected to the fluid pressure outlet, and the other is connected to the fluid pressure supply port.
A pressure difference occurs between the first variable pressure chamber and the second variable pressure chamber, the piston within the cylinder moves to the left or right, and the piston rod, which is the output shaft, moves in and out.

As the piston moves, a feedback screw shaft that is threadedly engaged with the piston is rotated in accordance with the amount of movement of the piston. This rotation of the feedback screw shaft is transmitted to the valve body of the valve device, which is connected to the feedback screw shaft so that it can be displaced in the axial direction, and the valve body of the valve device is first rotated in the direction in which the pilot screw shaft rotates. Rotate it. Therefore, when the difference in the relative rotation angle between the pilot screw shaft and the feedback screw shaft disappears and the valve body of the valve device returns to its original position and closes the flow path to the first variable pressure chamber and the second variable pressure chamber, the piston is turned off. Stop.

Therefore, if an electric motor such as a pulse motor is used as the input transmission means to move the valve body, the position of the piston rod, which is the output shaft, can be controlled in accordance with the rotation angle of the valve body. Moreover, since the valve body of the valve device is always returned to its original position by the feedback screw shaft, the valve body of the valve device only needs to have the minimum axial length necessary for its valve action, and the maximum movement range of the piston. There is no need for a long protrusion to cover the servo cylinder, so a small servo cylinder can be constructed.

[Example] The present invention will be described below based on illustrated embodiments.

In FIG. 1, 1 is a cylinder, 2 is a piston rod as an output shaft, and 3 is a piston that is slidably positioned within the cylinder 1 and partitions the inside of the cylinder 1 into left and right variable pressure chambers 4.5. The piston rod 2 is integrally formed with one side end of the piston 3 and protrudes from one end of the cylinder 1. Reference numeral 6 denotes a valve device that performs mechanical displacement according to the amount of rotation of the electric motor 7, and controls the variable pressure chambers 4.5 to reduce the pressure in one side and increase the pressure in the other. The piston 3 is connected to this valve device 6
By controlling the pressure in the variable pressure chamber 4.5 by the valve action, the electric motor 7 moves in either the left or right direction in the axial direction according to the amount of rotation of the electric motor 7 and comes to rest. 8 is a piston 3 that is displaced in this axial direction.
A feedback nut 9 carried by the cylinder 1 is a threaded shaft that is threadedly engaged with the nut 8, and is rotatably supported by a bearing 11 in a support plate 10 provided at the rear end of the cylinder 1. This screw shaft 9 is rotated by the amount of movement of the piston 3 as the nut 8 moves, and functions to feed back this to the mechanical displacement of the valve device 6.

In FIG. 2, 12 is a cylindrical body for configuring the valve device 6, one end of which is closed by an end plate 14 leaving a connection chamber 13, and the other end is closed by an end plate 15, and the cylinder l are coaxially connected to the screw shaft 9 via the support plate lO. The valve device 6 includes this cylindrical body 12, a driving poppet 16 fitted into the cylindrical body 12 so as to be slidable in the axial direction, and donut-shaped driven poppets 17 and 18 disposed on both sides of the driving poppet 16. and has. A step as a stopper 19.20 is formed on the inner wall of the cylinder 12 at a position apart in the axial direction, and the drive poppet 16 is moved to the stopper 19.2.
0, and the driven poppet 17.18 is arranged so as to be slidable in the range in which it abuts against this stop 19.20.

The outer periphery of both ends of the drive poppet 16 is formed as a small diameter portion to form a passage 21, 22 between it and the inner periphery of the cylindrical body 12,
The outer periphery of the driven poppet 17, 18 on the drive poppet 16 side is also formed as a small diameter portion to form a passage 23, 24 between it and the inner periphery of the cylindrical body 12. Stopper 19.2 above
0 is positioned as a valve seat for the driven poppet 17, 18, and is in a relationship capable of closing the 1 passage 23, 24. The driven poppet 17 is moved toward each other by a compression spring 25 disposed between the end plate 14 of the cylinder body 12, and the driven poppet 18 by a compression spring 26 disposed between the end plate 15 of the cylinder body 12. is energized by driven poppet) 17
．． 18 is usually.

Due to the action of elastic compression springs 25, 28, they remain stationary against the drive poppet 16 and the stopper 19, 20, respectively.

Thus, driven poppet) 17.18 and stopper 19.2
0, a first poppet valve 51 and a second poppet valve 52 are configured, which are opened by displacement of the driven poppet 17, 18 accompanied by the driving poppet 16, and
Between the driven poppet 17.18 and the drive poppet 16, the drive poppet 16 is displaced and the driven poppet 17.
The third poppet valve 53 is opened by moving away from 18.
and a fourth poppet valve 54.

Inside and outside of the cylindrical body 12, there is provided a discharge flow path that communicates one of the variable pressure chamber 4 and the variable pressure chamber 5 with the fluid outlet 30 via one of the first poppet valve 51 and the second poppet valve 52; A supply passage is formed that communicates the other of the variable pressure chambers 4 and 5 with the fluid supply port 34 via one of the poppet valves 53 and the fourth poppet valve 54.

To be more specific, a passage 27 that communicates the variable pressure chamber 5 of the cylinder 1 with the connection chamber 13 of the cylindrical body 12 is provided in the support plate IO at the rear end of the cylinder 3, and a passage 27 is provided inside the end plate 14 and the cylindrical body 12. An axial passage 28 that communicates this connection chamber 13 with an outer circumferential passage 21 of the drive poppet 16 and an outer circumferential passage 22 of the drive poppet 16.
A radial flow path 31 is provided for communicating the radial flow path 31 with the variable pressure chamber 4 of the cylinder 1, and an external pipe 32 is further provided for connecting the radial flow path 31 to the variable pressure chamber 4 of the cylinder 1. These are shared as part of the discharge flow path and the supply flow path.

The discharge flow path is connected to the common flow path, that is, the passage 27 and the axial flow path 28 or the radial flow path 31 and the pipe 32, and the cylinder body 12.
A radial passage 33.34 is provided radially within the driven poppet 17.18 and constantly communicates the outer circumferential passage 23.24 of the driven poppet 17.18 with the outside.

On the other hand, the supply flow path includes a groove 36 provided on the central peripheral surface of the drive poppet 16 and a radial flow path 35 provided inside the cylinder 12 that communicates the groove 36 of the drive poppet 16 with the fluid supply port 34. and an axial passage 37., which is connected at one end to the groove 36 of the drive poppet 16 and provided axially inside the drive poppet 16, and whose other end is open to be opened and closed by the driven poppet 17.18. It consists of 38. Drive poppet 1
The groove 36 of 6 is formed to have an axial length and width larger than the maximum stroke length of the drive poppet 16 limited by the stopper 19.20, so that even if the drive poppet 16 moves within the cylinder body 12, the drive The groove 36 of the poppet 16 and the radial flow path 35 are configured to always communicate with each other.

1st. The second poppet valves 51,52 each function here as a discharge control valve connecting the variable pressure chamber 4.5 with the fluid outlet 30, and the third. The fourth poppet valves 53, 54 each function as a supply control valve connecting the variable pressure chamber 4.5 to the fluid supply port 34. That is, when the driven poppet (17.18) is pushed away from the stopper (19.20) by the driving poppet (16), the first poppet (17.18) is pushed away from the stopper (19.20). The second poppet valve 51.52 opens, variable pressure chamber 4.5 - channel 27.28 or pipe 32 and radial channel 31 - channel 21.22 - poppet valve 51.52
A discharge flow path consisting of - passage 23.24 - flow path 29.33 - fluid outlet 30 is formed, and the variable pressure chambers 4, 5 are connected to the fluid outlet 30. Also, when the drive poppet 16 separates from the driven poppet 17.18, the third. The fourth poppet valve 53,54 opens, fluid supply port 34 - radial flow path 3
5-Groove 36-Axial flow path 37.38-Poppet valve 53.
54 - channel 21.22 - channel 28.27 or the supply channel consisting of radial channel 31 and pipe 32 - variable pressure chamber 4.5 is omitted, and variable pressure chamber 4.5 is connected to fluid supply port 34. Ru.

Shaft portions 39 and 41 are integrally formed on both sides of the drive poppet 16, and one of the shaft portions 39 is attached to the rear end of the threaded shaft 9 for feedback by means of a joint 40, so that the shaft portion 39 cannot be relatively rotated and is movable in the axial direction. is connected to. Also, the other shaft portion 4
1 is formed with a nut 42, which is threadedly engaged with a pilot threaded shaft 43 which is supported rotatably but immovably in the axial direction by a bearing 44 in the end plate 15 of the cylinder body 12. This pilot screw shaft 43 is connected to the coupling 18
It is connected to the output shaft 45 of the electric motor 7 via. Therefore, the electric motor 7 causes the pilot screw shaft 43 to
by being rotated.

The drive poppet 16 is moved to either the left or right by the action of the pilot nut 42 which is threadedly engaged with this.

That is, the rotation angle of the electric motor 7 is converted into the axial movement amount of the drive poppet 16, and the accompanying valve action of the valve device 6 causes the piston 3 and the piston rod 2 to move in the axial direction due to the action of fluid pressure. do.

Next, the operation of the servo cylinder with the above configuration will be explained. It is assumed here that the fluid supply port 34 is connected to an air pressure source (not shown).

First, a case in which the piston rod 2 moves backward in the right direction in the figure will be described.

When the electric motor 7 rotates the pilot screw shaft 43 counterclockwise (in the direction of arrow a) with respect to the pilot nut 42 of the drive poppet 16, the drive poppet 16 moves to the left, which is the direction away from the pilot screw shaft 43. Move in the direction of the arrow. The driven poppet 17 is a compression spring 25
The driven poppet 17 is pushed to the left against the stopper 1.
3, the first poppet valve 51 opens, whereby the variable pressure chamber 5 - passage 27.28 - passage 21 - poppet valve 5
A discharge passage consisting of 1-passage 23-flow passage 29-fluid outlet 30 is formed, and the variable pressure chamber 5 is connected to the fluid outlet 30 to be depressurized. On the other hand, regarding the variable pressure chamber 4, since the driven poppet 18 is restricted from moving to the left by the stopper 20, the driving poppet 16 moves away from the driven poppet 18, the fourth poppet valve 54 opens, and the fluid supply port 34
- radial passage 35 - groove 36 - axial passage 38 - poppet valve 54 - passage 22 - radial passage 31 - external piping 32
- A supply channel consisting of a variable pressure chamber 4 is formed, and the variable pressure chamber 4 is connected to the fluid supply port 34 to increase the pressure.

Therefore, the pressure difference between the pressure change chamber 4 and the pressure change chamber 5, that is, the pressure difference between the pressure change chamber 4 and the pressure change chamber 5,
Based on a large pressure difference approximately equal to the pressure applied to the piston 3, the piston 3 moves to the right (in the direction of arrow C) to a position proportional to the amount of rotation of the electric motor 7.

On the other hand, as the piston 3 moves backward, the feedback nut 8 also moves to the right (in the direction of arrow C), and the threaded shaft 9 that is threadedly engaged with the feedback nut 8 moves clockwise (in the direction of the arrow C) with respect to the drive poppet 16. d direction). This rotation is transmitted to the drive poppet 16 via the joint 40, and the drive poppet 16 similarly rotates clockwise (in the direction of arrow e) with respect to the pilot screw shaft 43. This driving poppet) 1
6 is the same direction as the direction in which the pilot screw shaft 43 first rotates, so the drive poppet 16 is rotated by the screw action so that the pilot screw shaft 43 is in the right direction (arrow f
direction).

In this way, the drive poppet 16, which initially moved away from the pilot screw shaft 43, is again moved toward the pilot screw shaft 43 and returns to the Iq position. Therefore, the first poppet valve 51 and the fourth poppet valve 54 are closed, and at that point, the exhaust of the variable pressure chamber 5 and the inflow of air pressure into the pneumatic chamber 4 are stopped, and the piston 3 is at the position after the movement. Stop.

Next, a case where the piston rod 2 protrudes to the left will be described.

When the pilot screw shaft 43 is reversed by the electric motor 7 and the drive poppet 16 is moved to the right in the figure (in the direction of arrow f), the driven poppet 18 is pushed to the right against the compression spring 26, and the driven poppet 18 is pushed to the right against the compression spring 26. is the second one away from the stopper 20.
The poppet valve 52 opens, and the variable pressure chamber 4 - external piping 32 - radial flow path 3! - Passage 22 - Second poppet valve 52 - Passage 2
A discharge passage consisting of 4-radial flow passage 33-fluid discharge port 30 is formed, and the variable pressure chamber 4 is communicated with the fluid discharge port 30 to be depressurized. On the other hand, between the voltage transformation chamber 5 and the driven poppet 1,
7 is restricted from moving to the right by the stopper 13, the driving poppet 16 moves away from the driven poppet 17, and the third poppet valve 53 opens, opening the fluid supply port 34-radial flow path 35-groove 36. A supply flow path consisting of - axial flow path 37 - third poppet valve 53 - passage 23 - flow path 28.27 - variable pressure chamber 5 is formed, and variable pressure chamber 5 is communicated with fluid supply port 34 to increase pressure. .

Therefore, the piston 3 moves to the left based on the pressure difference between the variable pressure chamber 4 and the variable pressure chamber 5, the feedback screw shaft 9 is rotated, and the drive poppet 16 eliminates the relative rotation difference with respect to the pilot screw shaft 43. direction (rotated and driven poppet) 1
6 moves to the left (in the direction of the arrow) and returns to its original position. As a result, the second poppet valve 52 and the third poppet valve 53 are closed, the exhaust of the variable pressure chamber 4 and the inflow of air pressure into the pneumatic chamber 5 are stopped, and the piston 3 is stopped at the position after the movement.

As described above, by using both the left and right chambers partitioned by the piston 3 in the cylinder 1 as variable pressure chambers, the electric motor 7 moves the drive poppet 16 against the force of the compression springs 25 and 26. With this, all the fluid pressure supplied from the fluid supply port 34 is effectively used, and the electric motor 7
Arbitrary positioning of the piston rod 2 according to the amount of rotation can be efficiently performed.

Furthermore, since the amount of displacement of the drive poppet 16 is returned to zero by the feedback action based on the movement of the piston rod 2, which is the output shaft, the position of the drive poppet 16 is always the same regardless of the movement position of the piston rod 2. It is in. Therefore, since the drive head 16 does not need to have its shaft portion 41 protrude as long as the maximum movement length of the piston rod 2, a small servo cylinder can be constructed as a whole.

In the above embodiment, the working medium of this servo cylinder is air. However, fluids other than air,
For example, a gas such as nitrogen gas.

It goes without saying that a liquid such as oil may be used, but if the working medium is air, a pneumatic line normally installed in a factory can be used as the compression drive source, so a hydraulic cylinder There is no need to provide a special hydraulic power source or piping. Further, even in food machines, pharmaceutical machines, etc. that dislike oil, there is an advantage that there is no need to worry about leakage of the working medium.

[Effects of the Invention] As described above, the present invention uses a valve device to switch the chambers on both sides of the piston in the cylinder as variable pressure chambers, increases the pressure in one variable pressure chamber and reduces the pressure in the other variable pressure chamber, and transfers the pressure from the pressure increasing side. Since the piston is moved toward the reduced pressure side, it can be quickly and stably positioned at any desired position even if a compressible fluid with relatively low pressure, such as air pressure, is used as the working medium.

In addition, the amount of movement of the piston is fed back to the valve body of the valve device by the feedback screw shaft, and when the valve body of the valve device returns to its original position, the flow path to the first variable pressure chamber and the second variable pressure chamber is closed, and the piston stops. Therefore, since the valve body of the valve device is always returned to its original position after being displaced, there is no need for it to protrude for a long time to cover the maximum movement range of the piston, as in the case of the conventional method.Therefore, the entire servo cylinder can be made smaller. Can be configured.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing one embodiment of a hydraulic servo cylinder of the present invention, FIG. 2 is a detailed sectional view thereof, and FIG. 3 is a schematic sectional view of a conventional hydraulic servo cylinder. In the figure, 1 is a cylinder, 2 is a piston rod, 3 is a piston, 4.5 is a variable pressure chamber, 6 is a valve device, 7 is an electric motor, 8
is a feedback nut, 9 is a feedback screw shaft, 12 is a cylinder, 16 is a driving poppet, 17.18 is a driven poppet, 19°20 is a stopper, 21.22 is a passage, 23.24 is a passage, 25.26 is a compression spring, 27.2
8 is a flow path, 29 is a radial flow path, 30 is a fluid outlet, 3
1 is a radial flow path, 32 is a pipe, 33 is a radial flow path,
34 is a fluid supply port, and 35 is a radial flow path. 36 is a groove, 37.38 is an axial flow path, 40 is a joint, 42
is the pilot nut, 43 is the pilot screw shaft, 4
4 represents a bearing, and 46 represents a coupling. Patent Applicant: Ishikawajima-Harima Heavy Industries Co., Ltd. Representative Patent Attorney: Nobuo Kinuya 7; 2: and °stonro..., de. 3; Binuton 4.5: Kitoko 6: 4f split 1L 7: Ki motor 8: Fu 4-t”tS knee = 7N; 4 no Suhe・Nodo 9
: Screw shaft 10: Support plate 11; Hair angle >7°. Figure 3

Claims (1)

[Claims] 1. A piston provided in a cylinder and having a piston rod serving as an output shaft at one end; a first variable pressure chamber and a second variable pressure chamber partitioned by the piston and formed in the cylinder;
It has a pilot screw shaft rotated by an electric motor, and a valve body that is sent in the axial direction by the rotation of the pilot screw shaft, and the axial displacement of the valve body causes one of the first pressure change chamber and the second pressure change chamber to be controlled. a valve device connecting the fluid pressure outlet and the other to the fluid pressure supply port, the valve device being coupled to be movable in an axial direction relative to the valve body of the valve device and being threadedly engaged with the piston; The first variable pressure chamber and the second
A fluid pressure system characterized by being provided with a feedback screw shaft that is rotated according to the amount of movement of the piston and returns the valve body of the valve device to its original position when the piston moves due to a pressure difference in the variable pressure chamber. servo cylinder.