JPS6267307A - Cushioning device for cylinder - Google Patents

Abstract

PURPOSE:To enable a shock to be absorbed easily through reducing the piston travel speed in the neighborhood of the end of piston stroke by detecting the arrival of the piston of a cylinder in the vicinity of its stroke end, and then, controlling a counter-balance valve which supplies and discharges pressure oil to and from the cylinder. CONSTITUTION:When a piston PS reaches its stroke end neighboring position E, a lowering signal from No.1 switch 44 in a travel direction detector G and a lowering signal from No.1 switch 46 in a position detector K are simultaneously entered into an AND circuit 50, and then, No.1 switching device 48 is changed over so that a desired pressure signal is entered into the main control unit D. Thereby, through the agency of a first order lag circuit 41 and an amplifier 42, the exciting current from a solenoid 23 is reduced in such a manner that an actual pressure signal agrees with the desired pressure signal. As the result of this, the opening of a counterbalance valve C in a control element becomes smaller, and also, the travel speed of the piston PS becomes lower, and accordingly, a cushioning effect can be produced therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cushion device that cushions the impact when a piston of a cylinder reaches its stroke end.

(Prior Art): In the conventional device shown in Fig. J44, the inside of the cylinder S is divided by the piston 1 into a rod side chamber 2 and a bottom side chamber 3.

The rod side chamber 2 is in direct communication with the supply/discharge boat 4, while the bottom side chamber 3 is in communication with the supply/discharge boat 6 via the cylindrical hole 5.

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

Now, when the cylinder 7 enters the cylindrical hole 5, the flow path area of the cylindrical hole 5 is substantially reduced, so resistance is imparted to the fluid flowing out from the bottom side chamber 3 to the supply/discharge boat. This resistance provides the desired cushioning effect.

(Problems to be Solved by the Present Invention) In the conventional device as described above, one cylinder 7 has a cylindrical hole 5.
The length of the stroke within the cylinder S determines the length of the process for exerting the cushioning function, but the total length of the cylinder S must be increased by the stroke of the cylinder 7.

However, as the total length of the cylinder increases, it becomes more difficult to reduce the weight of the cylinder, and the installation volume increases.

Furthermore, in this conventional device, the inner diameter of the cylindrical hole 5 and the cylinder 7 are
The effectiveness of the cushion is determined by the annular gap, which is the difference between the outer diameter of the cylinder and the outer diameter of the cylinder. there were.

Furthermore, since the deceleration rate changes in proportion to the cube of the value of 1/2 of the annular gap, the deceleration rate differs depending on a slight difference in the annular gap. For this reason, the dimensions of the cylindrical hole 5 and the cylinder 7 must be precisely controlled in gm units, which poses the problem of making machining that much more difficult.

A first object of the present invention is to provide a cushion device that does not require increasing the overall length of the cylinder.

A second object is to provide a device that can arbitrarily adjust the deceleration rate of the cylinder.

Furthermore, the purpose of :53 is to provide a device that eliminates the need for conventional cylindrical holes and cylinders that require strict dimensional control.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides one or more detectors for detecting the operating status of the cylinder, such as supply pressure and supply flow rate, and an output of this detector. A main controller that outputs a predetermined electric signal in response to the input signal, a counterbalance valve that performs a control operation in response to no signal from the main controller, and a piston of the cylinder. A moving direction detector that detects in which direction the piston is moving, a position detector that detects when the piston has reached the vicinity of the stroke end, and signals from these moving direction detectors and signals from the position detector. and an auxiliary controller that outputs a predetermined signal and transmits the output signal to the main controller when the auxiliary controller and the main controller input the piston of the cylinder. A signal for decelerating the moving speed of the main controller is output from the main controller.

(Operation of the present invention) Since the present invention is configured as described above, the counterbalance valve functions according to the operating condition of the cylinder, and even when a counter load acts, the cylinder moves according to the condition. Control speed.

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

(Effects of the Present Invention) Since the counterbalance valve is made to function as described above to exhibit the Kunjon effect, there is no need to provide a special mechanism to the cylinder.

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

Furthermore, since a counterbalance valve is used, there is no requirement for machining accuracy for cylindrical holes or cylinders, unlike in the past.

Furthermore, since the cushioning effect is exerted from the piston position detected by the position detector, by arbitrarily adjusting the detection position, the stroke that exerts the cushioning effect can be adjusted, and the effectiveness of the cushion can also be adjusted. .

(Embodiment of the present invention) In the embodiment shown in FIGS. 1 to 3, the rod side chamber 10 of the cylinder S for raising and lowering the load W is connected to the switching valve V
On the other hand, a passage 13 is connected to the bottom side chamber 12, and an operating check valve 14 is connected to this passage 13.
and counterbalance valve C are connected.

The operated check valve 14 normally only allows flow from the counterbalance valve C to the bottom side chamber 12 and blocks the reverse flow, but the pressure on the 5 passage 11 side acts on the operated 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 boat 16 is connected to the switching valve V via a passage 20, and the second port 1? is connected to the passage 13, and the third bow 18 is connected to the tank T. Furthermore, the fourth port 18 is connected to a pilot pump PP.

A valve hole 21 is formed in the main body 15, one end of which is closed with a closing member 22, and a proportional solenoid 23 is provided at the other end to control the stroke amount of the bushing rod 23a according to the exciting current. It is set up.

A control spool CV is housed in the valve hole 21, and a pilot spool Pv is movably housed in the control spool CV. A spring 25 is interposed between the control spool Cv and a spring receiver 24 provided on the closing member 22 side, and normally, due to the action of this spring 25, the end face of a spacer 26 provided adjacent to the proportional solenoid 23 is I am in contact with it.

Furthermore, the pilot spool Pv has a spring receiver 24
A spring 27 is interposed between the pilot spool PV and the tip end surface of the rod portion 24a, so that the pilot spool PV normally comes into contact with a stepped portion 26a formed on the inner diameter of the spacer 26.

A proportional solenoid 2 is placed at the tip of the pilot spool Pv, that is, at the end opposite to the spring 27.
The specific configurations of these two spools Pv and Cv are as follows.

That is, the control spool Cv is the first port)1.
A control portion 29 that forms a first annular recess 28 corresponding to B and tapers toward the first annular four portion 28 side.
is formed. When the control spool Cv moves against the spring 25, the control section 29 functions according to the movement position to control the opening degree when the first port 18 and the second port 17 communicate with each other. ing.

In addition to the first annular recess 28, a second annular recess 30
, while forming the third annular recess 31, the spacer 2B
An annular passage 32 is formed that is open to a pilot chamber 39 on the side.

The second annular recess 30 always communicates with the third port 18 regardless of the movement position of the control spool Cv, and via the hole 33 formed at the bottom of the fourth annular portion 30,
It communicates with the hollow portion 34 of the control spool Cv.

Further, the third annular portion 31 always communicates with the fourth boat +9 regardless of the movement position of the control spool Cv, but the hole 35 formed at the bottom of this annular recess 31 allows the movement of the pilot spool Pv. It opens and closes depending on the position. That is, when both spools cv and ps are in the normal position shown, the hole 35 is blocked by the pylon spool Pv, but when the pilot spool Pv moves against the spring 27, this hole 35 and the pilot spool Pv are closed. It communicates with the formed annular groove 36.

Furthermore, the annular passage 32 is always in communication with the annular groove 36 via a hole 37 formed in the control spool Cv.

The pyro/) spool Pv has a communication hole 38.
However, when only the control spool Cv moves against the spring 25 from a state where both spools CV and PS are in the positional relationship shown, the communication hole 38 opens to the pilot chamber 39 side. ing.

When the proportional solenoid 23 is excited, the bushing rod 23a strokes in accordance with the exciting current, and the pilot spool Pv is moved against the spring 27 in accordance with the stroke amount.

When the pilot spool Pv moves in this way, the third
Since the E5-shaped recess 31 and the annular groove 36 communicate with each other, the pressure oil from the pilot pump PP flows through the fourth port 19 → the third annular recess 31 → the hole 35 → the annular groove 36 → the hole 37 → the annular passage 3.
2 into the pilot chamber 39, and its pressure acts on the end face 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 degree of the first boat 16 and the second port 17 is determined depending on the position where the control spool Cv is stopped, which is ultimately proportional to the excitation current of the proportional slide/id 23.

That is, the control spool Cv moves following the pilot spool Pv, and the control spool Cv catches up with the pilot spool Pv.

Since the control spool CV stops when both spools CV and PS maintain the relative relationship shown, the amount of movement of the control spool Cv is proportional to the amount of movement of the pilot spool Pv. And this biloft spool Pv
The amount of movement of the control spool Cv is proportional to the stroke of the bushing rod 23a as described above, but the stroke of this bushing rod 23a is proportional to the excitation current of the proportional solenoid 23. It will be proportional to the current.

Now, if the switching valve V is switched from the neutral position shown in the figure to the left position, and the exciting current of the proportional solenoid 23 is maximized to maximize the opening degree in the control section 29, the first
A state of free flow occurs between the port 16 and the second board 7.

Therefore, the oil discharged from the pump P passes through the first passage 20 → the first port 16 → the first annular recess 28 → the control section 29 in the fully open state → the second port 17 → the operating check valve 14.
While being supplied to the bottom side chamber 12, the rod side chamber 10
Since the oil returns to the tank via the passage 11, the load W increases.

Also, when the switching valve V is switched to the right position in the drawing, the pump P
Pressure oil is supplied to the loft side chamber 10, and the supply pressure acts on the operating check valve 14 to open it.

At the same time, the proportional solenoid 23 is energized,
If the opening degree of the control section 29 is determined, the return oil from the bottom side chamber I2 will flow into the tank T according to the opening degree, so that the load W will decrease.

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

Note that when the proportional solenoid 23 is de-energized from the above state, the pilot spool Pv moves to the right in the drawing due to the action of the spring 27, and the communication hole 38 and the pilot chamber 3
9. Therefore, the pyro chamber 7)
communicates with the tank T via the hole 33 → second annular recess 30 → third port 18.

Since the pilot chamber 39 communicates with the tank T, the control spool Cv moves rightward in the drawing following the pylon spool Pv by the action of the spring 25, and returns to the position shown in the drawing.

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

This main controller has an arithmetic unit 40 and a first-order lag circuit 41 as its main elements, transmits a signal from this -order lag circuit 41 to the proportional solenoid 23 via an amplifier 42, and excites the proportional solenoid 23 according to the signal. It allows current to be obtained.

A pressure detector 43 is connected to the passage 11, and a pressure signal P1 detected by the pressure detector 43 is inputted to the calculation unit 40, and the calculation unit 40 combines the pressure signal P1 and the target pressure. The difference with the signal Per is calculated, and the calculation result is input to the first-order delay circuit 41.

The second-order delay circuit 41 multiplies the difference by α, which is a coefficient of the moving speed, to obtain the moving speed y. That is, si=α
Find (P+-Per).

Then, by further integrating this step, the side control spool C
The displacement of v 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 excitation current is controlled so that the pressure PI is stabilized at the target pressure Per.

As described above, control is performed by determining the difference between the target pressure signal Per and the pressure signal PI of the passage 11. This target pressure signal is set so that Pcrcr - Pcr3 can be selected, and is determined according to the operating status of the cylinder S. , a target pressure signal is determined, and this target pressure signal is selected by the auxiliary controller H1, the movement direction detector G, and the position detector.

The moving direction detector G includes a first switch 44 and a second switch 45 connected to the operating lever of the FjJ exchange valve V. When the switching valve V is switched to the right position in the figure and the piston PS is moved in the direction of the stroke end E of the bottom side chamber, the first switch 44 closes and outputs a descending signal. In addition, the switching valve V is switched to the left position and the piston P
When S is being moved toward the stroke end F on the rod side, the second switch 45 closes and outputs a rising signal.

The position detector also includes a first switch 4B and a second switch 47, and the piston PS is located in the bottom side chamber.
When the PS is near the end of the rod, that is, at a specific point E°, the first switch 4B closes and outputs a signal, and when the PS is at a specific point F° on the rod side, the second switch 47 closes and outputs a signal. Output.

Further, the auxiliary controller H includes the first to third vJ converters 48 to
50 as the main element, :JIjl switch 48
The terminal 51 of is always connected to the arithmetic unit 40.

One contact 52 of the first switch 48 is always connected to the terminal 53 of the second switch 48, and the target pressure signal PcB is always input to the other contact 54.

Normally, the terminal 51 and the contact 52 are connected. However, when the signals output from the first switch 44 of the moving direction detector G and the first switch 46 of the position detector KI7 are simultaneously input to the AND circuit 55, the terminal 51 and the other contact 54 are connected. I have to.

Furthermore, the target pressure signal Pcro is always input to one contact 5G of the second vJ switch 49, while the other contact 57 is always connected to the terminal 58 of the third switch 50.

Normally, the terminal 53 and the contact 58 are connected, but when the piston PS rises, the output signal from the second switch 45 of the moving direction detector G is transmitted to the second switch via the control circuit 59. When input to switch 48, terminal 53 and contact 4
8 is connected.

Further, the target pressure signal Pcr2 is always input to one contact 80 of the third switching device 50, and the target pressure signal Pcr3 is always input to the other contact 61.

Normally, the terminal 58 and the contact 60 are connected, but the signals output from the second switch 45 of the moving direction detector G and the second switch 47 of the position detector are simultaneously input to the AND circuit 62. When the terminal 58 and the other contact 81
I am trying to connect it with.

For the above configuration, the lowest value of the pressure signal P1 is P+
N, the piston PS moves from the specific point F'' to the stroke end F.
P+M is the maximum value of the pressure signal P1 when moving toward
Then, Pcr2 <P+N<Pcr.

<Pcrl and P 1 M<P Cr3 .

Therefore, when the switching valve V is in the neutral position and the piston PS is at rest, the supply flow rate does not flow into the passage 11, so the pressure signal P1 becomes P, =PIN, which is the minimum. At this time, each switch of the auxiliary controller H maintains the state shown in the figure, so Pcr=Pcr.

It becomes. Since pIN<Pcro is set, (P+ - Per)<O, and the exciting current of the proportional solenoid 23 becomes O. Therefore, the control section 29 of the counterbalance valve C maintains the fully closed state.

Next, switch the switching valve V to the right position in the drawing, and
When S is moved toward a specific point E° in the bottom side chamber, a falling signal from the first switch 44 of the moving direction detector G is input to the AND circuit 50. However, the piston PS is above I
Until E' is reached, the downward signal from the first switch 46 to the position detector is not applied to the AND circuit 50, so the first switch 48 of the auxiliary controller H maintains the state shown, and the target A pressure signal Pcro is input to the main controller.

Therefore, the counterbalance valve C has a pressure P! in one passage ll! The opening degree of the control section 29 is adjusted so that Pcro is stabilized at the target pressure signal Pcro.

When the piston PS reaches the above-mentioned position E', the descending signal of the first switch 44 of the first movement direction detector G and the descending signal a of the first switch 46 of the position detector are simultaneously input to the AND circuit 50. Therefore, the first switch 48 is switched, the terminal 51 and the contact 54 are connected, and the target pressure signal Pcrl is input to the main controller.

However, even if the piston PS reaches position E', the passage ll
Since the pressure inside remains stable at P1=Pcro, the value of (P+ - Pcrl) output from the calculation section 40 becomes (PH-Pcrl) <O.

Then, due to the action of the -order lag circuit 41 and the amplifier 42,
Proportional solenoid 2 until (Pl - Per) becomes (Pt - Pcn ) = O, that is ]'
Since the excitation TL flow of No. 3 is reduced, the opening degree of the control section 29 of the counterbalance valve C becomes smaller.

In this way, when the opening degree of the control section 29 becomes smaller, the flow rate passing through one passage 13 per unit time decreases, so the moving speed of the piston PS is reduced, and a cushioning effect is exerted.

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

At this time, if the piston PS has not reached the specific point F' of the rod side chamber 10, only the signal from the moving direction detector G is input to the AND circuit 62, so the third switching device 50 maintains the illustrated position. do. Therefore, the pressure signal Pcr2 input to the contact point 60 is input to the calculation unit 40, and the target pressure signal Pcr=Pcr2.

Since the target pressure signal Pcr2 is set to Per2<Pul, the output (PH-Per) of the calculation unit 40 is (
Pl-Pcr)>O. Therefore, the excitation current to the proportional solenoid 23 becomes maximum, and the control section 29 of the counterbalance valve C is fully opened to maintain a free flow state.

When the piston PS continues to rise as described above and reaches the specific point F', a signal is also output from the second switch 47 to the position detector.

The AND circuit 62 detects the direction of movement! The output signal of itG and the output signal of the position detector are input simultaneously. Therefore, a signal is output from the AND circuit B2, the third switch 50 is switched by the signal, the terminal 58 and the contact 61 are connected, and the pressure signal Pcr is output from the calculation unit 40.
3 is input, and the target pressure signal Per is Pcr=Pc
Then, when the piston PS moves up between the bottom side stroke end E and the specific point F' toward the specific point F', PIM such that P1≦PIM is obtained with respect to the pressure signal P1. always exists. Therefore, if Pcr3 is set so that PIM<Per:+ as described above, while the piston PS is rising from the specific point F° toward the stroke end F, the output of the calculation unit 40 is (P+ -Pe
r) is always (P+ −Pcr)×O. Therefore, the displacement signal y, which is the output of the -order delay circuit 41, gradually decreases due to the action of the coefficient α and the integrator 48, and the exciting current of the proportional solenoid 23 also gradually decreases.

As the excitation current gradually decreases in this way, the opening degree of the control section 29 of the counterbalance valve C gradually decreases from the fully open state, and the 1i amount of fluid supplied to the bottom side chamber 12 per unit time gradually decreases. will decrease. Therefore, in the process of the piston PS moving from the specific point F° toward the stroke end F, its moving speed is reduced, and a cushioning effect is produced.

Note that the target pressure signals Pcrl and Pcr3 are arbitrarily selected within the above setting range, and the first
By adjusting the mounting positions of the switch 46 and the second switch 47, the positions of the specific points E° and Fo can be changed. Therefore, the effectiveness of the cushion, that is, the deceleration rate of the other piston PS and the cushion stroke length can be easily externally adjusted.

Also, instead of the 1.2 switch 4847, the piston P
A displacement detector that detects the displacement of the switching valve V may be used, or a displacement detector that detects the displacement of the operating lever of the switching valve V or the spool may be used.

Another embodiment shown in FIG. 3 is a counterbalance valve C
This figure shows a number of signal sources for controlling the opening degree of the control section 29.

That is, a flow rate detector 63 that detects the supply flow rate on the first passage 13 side, a rotation speed detector 64 that detects the discharge flow rate from the rotation speed of the pump P, and a pressure detector 65 that detects the pressure on the passage 14 side. A position detector 66 for detecting the position of the piston PS is provided, and output signals from these detectors are transmitted to the main controller.

The main controller calculates based on one or more of the output signals from each controller as described above, and controls the excitation current to the proportional solenoid 23.

For example, when controlling only with the flow rate detector 83, a target flow rate signal is set and the flow rate in the passage 13 is controlled so as to reach the target flow rate.

[Brief explanation of drawings]

Drawings 1 and 2 show an embodiment of this invention, and the first
The figure is a circuit diagram, Figure 2 is a cross-sectional view of the counterbalance valve,
FIG. 3 is a circuit diagram of another embodiment, and FIG. 4 is a sectional view of a cylinder provided with a conventional cushion device. S...Cylinder, PS...Piston, C...Counter 7 to lance valve, D...Main controller, H...Auxiliary control blade, 43...Pressure detector, G... Movement direction detection base, K...position detector, 63...flow rate detector, 64
...Rotation speed detector, 65...Pressure detector, -80.
...Position detector.

Claims (1)

[Claims] One or more detectors that detect the operating status of the cylinder, such as supply pressure and supply flow rate, and a main controller that receives the output signal of this detector and outputs a predetermined electrical signal in accordance with the signal. a counterbalance valve that performs control operations according to electrical signals from the main controller; a movement direction detector that detects in which direction the piston of the cylinder is moving; When the position detector detects that the position has been reached, and the signal from these moving direction detectors and the signal from the position detector are simultaneously input, a predetermined signal is output and the output signal is sent to the main controller. and an auxiliary controller for transmitting data to the main controller, the cylinder cushion having a configuration in which, when a signal is transmitted from the auxiliary controller to the main controller, a signal for decelerating the moving speed of the piston of the cylinder is output from the main controller. Device.