JPH0678761B2 - Cylinder cushion device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cushion device that cushions a shock of a piston of a cylinder when the piston reaches a stroke end.

(Prior Art) In the conventional device shown in FIG. 3, the inside of the cylinder S is divided into a rod side chamber 2 and a bottom side chamber 3 by a piston 1.

The rod-side chamber 2 directly communicates with the supply / discharge port 4, while the bottom-side chamber 3 communicates with the supply / discharge port 6 via the cylindrical hole 5.

Further, a cylinder 7 is projected from the side surface of the piston 1 facing the bottom chamber 3 so that the cylinder 7 enters the cylindrical hole 5 at the stroke end portion of the piston 1.

Occasionally, when the column 7 enters the cylindrical hole 5, the flow passage area of the cylindrical hole 5 is substantially reduced, so that resistance is imparted to the fluid flowing from the bottom chamber 3 to the supply / discharge port, and The desired cushioning effect is exerted by this resistance.

(Problems to be Solved by the Present Invention) In the conventional device as described above, the cylinder 7 has the cylindrical hole 5
The length of the stroke in which the stroke length exerts the cushion function is determined, but the total length of the cylinder S must be increased by the stroke of the cylinder 7.

However, there has been a problem that the longer the overall length of the cylinder, the more difficult it is to reduce the weight of the cylinder and the larger the mounting volume thereof.

Further, in this conventional device, the inner diameter of the cylindrical hole 5 and the column 7
Since the effectiveness of the cushion is determined by the annular gap that is the difference between the outer diameter of the cylinder and the outer diameter of the cylinder, there is a problem that the effect of the cushion cannot be adjusted by adjusting the deceleration rate of the piston in the cylinder once assembled. .

Further, since the deceleration rate changes in proportion to the cube of the 1/2 value of the annular clearance, the deceleration rate varies due to a slight difference between the annular clearances. For this reason, the dimensions of the cylindrical hole 5 and the column 7 must be controlled in units of .mu.m, which makes the processing difficult.

A first object of the invention is to provide a cushioning device that does not require the cylinder to have a long overall length.

A second object is to provide a device capable of arbitrarily adjusting the deceleration rate of the cylinder.

Further, a third object is to provide a device that does not require a conventional cylindrical hole or column that requires strict dimensional control.

(Means for Solving Problems) In order to achieve the above object, the present invention provides one or a plurality of detectors for detecting an operating state of the cylinder such as a supply pressure and a supply flow rate, and an output of the detector. When a signal is input, a main controller that outputs a predetermined electric signal according to the signal, a counter balance valve that performs a control operation according to the electric signal from the main controller, and a piston of the cylinder The moving direction detector that detects whether the piston is moving in the direction, the position detector that detects that the piston has reached the vicinity of the stroke end, and the signal from these moving direction detectors and the signal from the position detector When inputting at the same time, it is equipped with an auxiliary controller that outputs a predetermined signal and transmits the output signal to the main controller, and when the signal is transmitted from the auxiliary controller to the main controller, the piston of the cylinder The signal for decelerating the moving speed is output from the main controller.

(Operation of the present invention) Since the present invention is configured as described above, the counter balance valve functions according to the operating state of the cylinder, and when the counter load acts, the movement of the cylinder according to that state is also performed. Control the speed.

Further, when the piston of the cylinder reaches the vicinity of the stroke end, the position detector detects it and causes the counterbalance valve to function to reduce the moving speed of the piston.

(Effect of the present invention) Since the counterbalance valve is made to function and the cushioning effect is exerted as described above, it is not necessary to provide the cylinder with a special function.

Therefore, it is not necessary to increase the overall length of the cylinder, which contributes to weight reduction and the mounting capacity can be reduced.

Further, since the counter balance valve is used, it is not necessary to have the processing accuracy of the cylindrical hole or the column unlike the conventional case.

Further, since the cushion effect is exerted from the piston position detected by the position detector, the stroke for exerting the cushion effect can be adjusted and the effectiveness of the cushion can be adjusted by adjusting the detected position arbitrarily. .

(Embodiment of the present invention) In the embodiment shown in FIGS. 1 and 2, the rod side chamber 10 of the cylinder S for raising and lowering the load W is connected to the switching valve V via the passage 11, while the bottom side chamber 12 is provided. The passage 13 is connected, and the operate check valve 14 and the counter balance valve C are connected to the passage 13.

The operation check valve 14 normally allows only the flow from the counterbalance valve C to the bottom side chamber 12 and blocks the reverse flow, but the pressure on the passage 11 side acts on the operation check valve 14. The valve is sometimes opened to allow reverse flow.

Further, the counterbalance valve C has first to fourth ports 16 to 19 formed in its main body 15.

The first port 16 is connected to the switching valve V via a passage 20, the second port 17 is connected to the passage 13, and the third port 18 is connected to the tank T. Further, the fourth port 19 is connected to the pilot pump PP.

A valve hole 21 is formed in the main body 15 and the valve hole 21 is formed.
One end of 21 is closed by a closing member 22, and the other end is provided with a proportional solenoid 23 that controls the stroke amount of a push rod 23a according to the exciting current.

Then, in the valve hole 21, the control spool CV is installed, and the pilot spool PV is attached to the control spool CV.
The interior is freely movable. The control spool CV has a spring between the spring receiver 24 provided on the closing member 22 side.
25 is interposed, and normally by the action of this spring 25, it is brought into contact with the end surface of the spacer 26 provided adjacent to the proportional solenoid 23.

Further, the pilot spool PV has a spring 27 interposed between the pilot spool PV and the tip surface of the rod portion 24a of the spring receiver 24, and normally the pilot spool PV comes into contact with the step portion 26a formed on the inner diameter of the spacer 26. I am trying.

Then, the tip of the pilot spool PV, that is,
The push rod 23a of the proportional solenoid 23 acts on the end opposite to the spring 27, and the specific configurations of these spools PV and CV are as follows.

That is, the control spool CV forms a first annular recess 28 corresponding to the first port 16, and
A control unit 29 is formed which is tapered toward the annular recess 28 side. Then, when the control spool CV moves against the spring 25, the control unit 29 functions according to the moving position to control the opening degree when the first port 16 and the second port 17 are in communication. ing.

In addition to the first annular recess 28, a second annular recess 30 and a third annular recess 31 are formed, and an annular passage 32 opened to the pilot chamber 39 on the spacer 26 side is formed.

The second annular recess 30 always communicates with the third port 18 regardless of the movement position of the control spool CV, and through the hole 33 formed at the bottom of the annular recess 30, the hollow part of the control spool CV. I have a relationship with 34.

Also, the third annular recess 31 always communicates with the fourth port 19 regardless of the position of movement of the control spool CV, but the hole 35 formed at the bottom of the annular recess 31 has a hole 35 formed therein for moving the pilot spool PV. It opens and closes according to the position. That is, when both spools CV and PS are in the normal position shown, the hole 35 is blocked by the pilot spool PV, but when the pilot spool PV moves against the spring 27, the hole 35 and the pilot spool PV are formed. The annular groove 36 is communicated.

Further, the annular passage 32 is a hole formed in the control spool CV.
The annular groove 36 is in continuous communication with the via 37.

A communication hole 38 is formed in the pilot spool PV, but when only the control spool CV moves against the spring 25 from the state where the spools CV and PS are in the positional relationship shown in the drawing, the communication hole 38 is formed. 38 is open to the pilot room 39 side.

Then, when the proportional solenoid 23 is excited, the push rod 23a makes a stroke according to the exciting current, and the pilot spool
Move PV against spring 27.

When the pilot spool PV moves in this way, the third annular recess 31 and the annular groove 36 communicate with each other, so that the pressure oil from the pilot pump PP flows from the fourth port 19 to the third annular recess 31 to the hole.
It flows into the pilot chamber 39 via 35 → annular groove 36 → hole 37 → annular passage 32, and its pressure acts on the end surface of the control spool CV.

When this pilot pressure acts, the control spool CV moves against the spring 25 and stops at a position where the hole 35 of the control spool CV is blocked by the pilot spool PV. In this way, the opening degrees of the first port 16 and the second port 17 are determined according to the position where the control spool CV is stopped, which is eventually proportional to the exciting current of the proportional solenoid 23.

That is, the control spool CV is the pilot spool PV.
When the control spool CV catches up with the pilot spool PV and the two spools CV and PS maintain the relative relationship shown in the drawing, the control spool CV stops, so that the control spool CV moves. The amount is proportional to the amount of movement of the pilot spool PV. The movement amount of the pilot spool PV is proportional to the stroke of the push rod 23a as described above.
Since the stroke of 3a is proportional to the exciting current of the proportional solenoid 23, the movement amount of the control spool CV is proportional to the exciting current of the proportional solenoid 23.

Now, when the switching valve V is switched from the neutral position in the drawing to the left position, and the exciting current of the proportional solenoid 23 is maximized to maximize the opening degree in the control unit 29, the first port 16 and the second port 17 will be described. In the meantime, it will be in a free flow state.

Therefore, the oil discharged from the pump P is passed from the passage 20 to the first port.
16-> first annular recess 28-> fully open control unit 29-> second port
17 → Bottom side chamber 12 via operate check valve 14
And the oil in the rod-side chamber 10 returns to the tank via the passage 11, the load W increases.

When the switching valve V is switched to the right position in the drawing, the pump P
The pressure oil from is supplied to the rod side chamber 10, and the supplied pressure acts on the operating check valve 14 to open it.

At the same time, by exciting the proportional solenoid 23 to determine the opening of the controller 29, depending on the opening,
Since the return oil from the bottom chamber 12 returns to the tank T, the load W drops.

The descending speed of the load W is determined according to the opening degree of the control unit 29, and the opening degree is controlled by the exciting current of the proportional solenoid 23.

When the proportional solenoid 23 is de-energized from the above state, the pilot spool PV moves to the right in the drawing by the action of the spring 27, so that the communication hole 38 and the pilot chamber 39 communicate with each other. Therefore, the pilot chamber 39 communicates with the tank T via the hole 33 → the second annular recess 30 → the third port 18.

Since the pilot chamber 39 communicates with the tank T, the control spool CV is acted by the spring 25 so that the pilot spool PV
Following this, it moves to the right in the drawing and returns to the position shown.

The main controller D shown in FIG. 1 controls the exciting current for determining the opening degree of the control unit 29 as described above.

The main controller D has a computing unit 40 and a primary delay circuit 41 as main elements, transmits a signal from the primary delay circuit 41 to the proportional solenoid 23 via an amplifier 42, and an exciting current corresponding to the signal. Is being obtained.

Then, a pressure detector 43 is connected to the passage 11, and the pressure signal P ₁ detected by the pressure detector 43 is input to the calculation unit 40, and in the calculation unit 40, the pressure signal P ₁ and The difference from the target pressure signal P _cr is calculated, and the calculation result is input to the first-order delay circuit 41.

The primary delay circuit 41 multiplies the difference by α, which is a coefficient of the moving speed, to obtain the moving speed y. That is, = α
_Find (P ₁ −P _cr ).

Then, by further integrating this, the control spool CV
Is calculated, and this valve displacement signal is input to the proportional solenoid 23 as an exciting current via the amplifier 42. That is, the exciting current is controlled so that the pressure P ₁ becomes stable at the target pressure P _cr .

As described above, the target pressure signal P _cr and the pressure signal P _cr in the passage 11 are set.
While controlling obtains the difference between _1, the target pressure signal, P
_{Although it is possible} to select _cr0 to _Pcr3 and determine the target pressure signal according to the operating state of the cylinder S, the target pressure signal is selected by the auxiliary controller H,
A moving direction detector G and a position detector K.

The moving direction detector G comprises a first switch 44 and a second switch 45 connected to the operation lever of the switching valve V. Then, when the switching valve V is switched to the right position in the drawing and the piston PS is being moved in the direction of the stroke end E of the bottom side chamber, the first switch 44 is closed and the down signal is output. Further, when the switching valve V is switched to the left side position and the piston PS is being moved in the direction of the stroke end F on the rod side, the second switch 45 is closed and the rising signal is output.

The position detector K also includes a first switch 46 and a second switch 47.
When the piston PS is in the vicinity of the sloak end of the bottom chamber, that is, at the specific point E ', the first switch 46 closes and outputs a signal. When the piston PS is at the specific point F'on the rod side, The second switch 47 closes and outputs a signal.

Further, the auxiliary controller H is mainly composed of the first to third switching devices 48 to 50, and the terminal 51 of the first switching device 48 is always connected to the arithmetic unit 40.

Then, one contact 52 of the first switching device 48 has a second switching device.
Although the target pressure signal P _cr1 is always input to the contact 54 of the other force, it is normally connected to the terminal 53 of 49, but normally, the terminal 51 and the contact 52
And are trying to connect. However, when signals output from the first switch 44 of the moving direction detector G and the first switch 46 of the position detector K are simultaneously input to the AND circuit 55, the terminal 51 and the other contact 54 are connected. I have to.

Further, the target pressure signal P is applied to one contact 56 of the second switch 49.
_cr0 is always input, but the other contact 57 is the third switch 5
Always connected to terminal 0 of 0. And usually terminal 53
Although the contact 56 is connected to the contact 56, when the output signal from the second switch 45 of the movement direction detector G is input to the second switch 49 via the control circuit 59 when the piston PS is raised, The terminal 53 and the contact 57 are connected.

Furthermore, the target pressure signal is applied to one contact 60 of the third switching device 50.
P _cr2 is always input and the target pressure signal P _cr3 is input to the other contact 61.
Is always input.

The terminal 58 and the contact 60 are normally connected, but the second switch 45 of the movement direction detector G and the second switch 45 of the position detector K are connected.
The signals output from the switch 47 and the AND circuit 62 simultaneously
When input to the terminal 58, the terminal 58 is connected to the other contact 61.

In the above configuration, the minimum value of the pressure signal P ₁ is P ₁ N, and the maximum value of the pressure signal P ₁ when the piston PS moves from the specific point F ′ toward the stroke end F is P ₁ M Then,
P _cr2 <P ₁ N <P _cr0 <P _cr1 and P ₁ M <P _cr3 are set.

Then, when the switching valve V is in the neutral position and the piston PS is stopped, the supply flow rate does not flow in the passage 11, so the pressure signal P ₁ becomes P ₁ = P ₁ N and becomes minimum. . At this time, since each switch of the auxiliary controller H maintains the illustrated state,
P _cr = P _cr0 . Since P ₁ N <P _cr0 is set, (P ₁ −P _cr ) <0, and the proportional solenoid 2
The exciting current of 3 becomes 0. Therefore, the control unit 29 of the counter balance valve C maintains the fully closed state.

Next, switch the switching valve V to the position on the right side of the drawing to move the piston PS
Is moved toward a specific point E'of the bottom side chamber, the down signal of the first switch 44 of the movement direction detector G causes the AND circuit to move.
Enter 55. However, since the down signal from the first switch 46 of the position detector K is not input to the AND circuit 50 until the piston PS reaches the position E ', the auxiliary controller H
The first changeover device 48 maintains the illustrated state, and the target pressure signal P
_cr0 is input to the main controller D.

Therefore, the opening degree of the control unit 29 of the counter balance valve C is adjusted so that the pressure P ₁ in the passage 11 _becomes stable at the target pressure signal P _cr0 .

When the piston PS reaches the position E ', the downward signal of the first switch 44 of the movement direction detector G and the position detector K are detected.
Since the down signal of the first switch 46 of the above is simultaneously input to the AND circuit 55, the first switch 48 is switched to contact the terminal 51 and the contact.
54 and the target pressure signal P _cr1 is input to the main controller D.

However, even if the piston PS reaches the position E ′, the pressure in the passage 11 remains stable at P ₁ = P _cr0 , so the value of (P ₁ −P _cr1 ) output from the calculation unit 40 is (P ₁ −P _cr1 ). _1- P _cr1 ) <0.

Then, by the action of the first-order delay circuit 41 and the amplifier 42, (P ₁
Since the exciting current of the proportional solenoid 23 is decreased until −P _cr ) becomes (P ₁ −P _cr1 ) = 0, that is, P ₁ −P _cr1 , the opening degree of the control unit 29 of the counter balance valve C is further increased. Get smaller.

Thus, if the opening of the control unit 29 becomes smaller, the passage 13
Since the flow rate per unit time passing through is reduced, the moving speed of the piston PS is reduced, and a cushioning effect is exhibited.

Further, when the switching valve V is switched to the left position in the drawing in order to raise the piston PS, the rising signal from the second switch 45 of the movement direction detector G is transmitted via the control circuit 59 to the second switching device.
Since it is input to 49, this second switching device 49 switches and the terminal
53 and contact 57 are connected.

At this time, the piston PS moves to the specific point F'of the rod side chamber 10
If not reached, the AND circuit 62 receives only the signal from the moving direction detector G, and the third switch 50 holds the position shown in the figure. Therefore, the pressure signal P _cr2 input to the contact 60 is input to the calculation unit 40, and the target pressure signal P _cr = P _cr2 .

Since the target pressure signal P _cr2 is set to P _cr2 <P ₁ N, the output (P ₁ −P _cr ) of the calculation unit 40 is (P ₁ −P _cr )> 0. Therefore, the exciting current to the proportional solenoid 23 becomes maximum, the control unit 29 of the counter balance valve C is fully opened, and the free flow state is maintained.

When the piston PS continues to rise as described above and reaches the specific point F ', the second switch of the position detector K
Since a signal is also output from 47, the output signal of the moving direction detector G and the output signal of the position detector K are input to the AND circuit 62 at the same time. Therefore, a signal is output from the AND circuit 62, the third switch 50 is _switched by the signal, the terminal 58 and the contact point 61 are connected, and the pressure signal P _cr3 is input to the arithmetic unit 40 and the target thereof. Pressure signal P _cr = P _cr =
It becomes P _cr3 .

Then, when the piston PS rises between the stroke end E on the bottom side and the specific point F ′ toward the specific point F ′, P ₁ ≦ P ₁ M for the pressure signal P ₁ is satisfied. ₁ M always exists. Therefore, by setting the P _cr3 such that P ₁ M <P _cr3 as described above, while the piston PS is raised toward the stroke end F from a specific point F ', is the output of the arithmetic unit 40 (P ₁ -P _cr) is always a _{(P 1 -P cr) <0} . Therefore, the displacement signal y, which is the output of the first-order delay circuit 41, gradually decreases due to the action of the coefficient α and the integrator, and the exciting current of the proportional solenoid 23 also gradually decreases.

Since the exciting current gradually decreases in this way, the opening degree of the control unit 29 of the counterbalance valve C gradually decreases from the fully opened state, and the flow rate of the fluid supplied to the bottom side chamber 12 per unit time gradually decreases. Less. Therefore, in the process in which the piston PS moves from the specific point F ′ toward the stroke end F, the moving speed of the piston PS is decelerated and the cushion effect is exerted.

The target pressure signals P _cr1 and P _cr3 are arbitrarily selected within the above setting range, and the mounting positions of the first switch 46 and the second switch 47 of the position detector are adjusted to determine the specific point E ′. The positions of F and F'can be changed. Therefore, the effectiveness of the cushion, that is, the deceleration rate of the piston PS,
External adjustment of the cushion stroke length is also easy.

Further, instead of the first and second switches 4647, a displacement detector for detecting the displacement of the piston PS may be used, or a displacement detector for detecting the displacement of the operation lever of the switching valve V or the spool may be used. May be.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention.
Figure is a circuit diagram, Figure 2 is a sectional view of a counterbalance valve,
FIG. 3 is a sectional view of a cylinder provided with a conventional cushion device. S ... Cylinder, PS ... Piston, C ... Counterbalance valve, D ... Main controller, H ... Auxiliary controller, 43 ... Pressure detector,
G ... moving direction detector, K ... position detector, 63 ... flow rate detector, 64 ... rotation speed detector, 65 ... pressure detector, 60 ... position detector.

Claims (1)

[Claims] Claim: What is claimed is: 1. A detector for detecting an operating condition of a cylinder such as a supply pressure and a supply flow rate, and a difference between an input signal from an output signal of the detector and a target signal. , A main controller that outputs a predetermined electric signal to make the difference zero, a counter balance valve that performs a control operation according to the electric signal from this main controller, and the piston of the cylinder in any direction A moving direction detector that detects whether the robot is moving, a position detector that detects when the piston has reached the vicinity of the stroke end, and a signal from these moving direction detectors and a signal from the position detector are input at the same time. When a signal is transmitted from the auxiliary controller to the main controller, the movement speed of the piston of the cylinder is controlled by outputting a predetermined signal and transmitting the output signal to the main controller. Signal causes the speed is, the cushion device of a cylinder which is configured to be outputted from the main controller.