JP2009041711A - Control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device wherein the size of the whole device is not increased and also its cost is not increased. <P>SOLUTION: In a first circuit system 6, a switching valve 5 having a reproduction function for reproducing a returning fluid from an actuator 14 to a supply side is provided, a throttle 29 for reproduction is provided for passages 9, 50 which are used as a returning side when the switching valve is switched to a reproduction position so that the returning fuid is reproduced with pressure equivalent to a pressure loss of the fluid passing through the throttle 29 for reproduction. A center open passage 24 for introducing a supply fluid of a second pump P2 when switching valves 16-21 provided in a second circuit system 23 keep holding their neutral positions is provided and a neutral cut valve 28 for opening and closing the center open passage 24 is provided at its most-downstream position. The neutral cut valve 28 is constituted of a spool valve, and the throttle 29 for reproduction is also provided for the neutral cut valve 28. The throttle 29 for reproduction is a variable throttle for varying an opening according to a switching quantity of the neutral cut valve 28. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device optimal for a construction machine having, for example, an arm cylinder and having a function of regenerating the return fluid of the arm cylinder to the supply side.

For example, some construction machines equipped with an arm cylinder have a so-called regeneration function that returns the return fluid of the arm cylinder to the supply side. In order to perform this regeneration function, a regeneration restrictor is provided in the return side passage during regeneration, and the return fluid is supplied to the supply side with a pressure corresponding to the pressure loss when the return fluid passes through the restrictor. I try to play it.
As such a control device having a reproduction function, a device described in Patent Document 1 is conventionally known.

  In the above-described conventional apparatus, the aperture indicated by reference numeral 52 in FIG. That is, the switching valve that controls the arm cylinder is slidably incorporated with the spool in the valve body, and the return fluid from the arm cylinder is regenerated to the supply side in accordance with the relative position of the spool. . A passage for regenerating the return fluid to the supply side is formed in the valve body, and the regeneration throttle (reference numeral 52 in the publication) is formed in the passage.

As described above, apart from forming the regeneration throttle in the valve body of the switching valve as in the device described in Patent Document 1, for example, the regeneration throttle controls a specific actuator that requires regeneration. It is also conceivable to provide an external switch valve. FIG. 6 and FIG. 7 show examples in which the switching valve is externally attached.
FIG. 6 shows a hydraulic control circuit for a power shovel that is a construction machine, and includes a first pump P1 and a second pump P2. Then, the traveling switch valve 1, the standby switching valve 2, the turning switching valve 3, the boom II switching valve 4 and the arm I switching valve 5 are sequentially connected to the first pump P1 from the upstream side thereof. These switching valves 1 to 5 constitute a first circuit system 6. When each of these switching valves 1 to 5 is in the neutral position as shown in the drawing, the center open passage 7 is opened, and the fluid discharged from the first pump P1 is guided to the tank T via the tank passage 11. I am doing so. In addition, the code | symbol 8 is a parallel channel | path and connects each switching valve 1-5 in parallel with respect to the 1st pump P1.

When the switching valve 5 for the arm I located on the most downstream side is switched to the regeneration position on the left side of the drawing, the regeneration is made external to the switching valve 5 for the arm I in the return passage 9. The diaphragm means 10 is connected. The regeneration throttle means 10 communicates with the tank T via the tank passage 11, and when a fluid flows from the return passage 9 to the tank T via the regeneration throttle means 10, the pressure corresponding to the pressure loss is supplied to the return passage 9. Is generated.
The fluid holding the pressure in this way is supplied to the supply side passage 13 via the check valve 12 and supplied to the piston side chamber 14 a of the arm cylinder 14. That is, the return fluid from the rod side chamber 14 b of the arm cylinder 14 is regenerated to the piston side chamber 14 a of the arm cylinder 14 via the return passage 9.

In addition, when the fluid is regenerated in the piston side chamber 14a of the arm cylinder 14 as described above, the load is acting on the arm cylinder 14 in the direction of the arrow 15 while the rod of the arm cylinder 14 is extended. When performing excavation work, the load direction is reversed. At this time, the check valve 12 is closed by the load pressure so that the pressure fluid from the first pump P1 does not escape to the return passage 9 side.
When the arm I switching valve 5 is switched to the right in the drawing, the supply fluid from the first pump P1 is supplied to the rod side chamber 14b of the arm cylinder 14 via the supply passage 13 and the piston side chamber. The entire amount of the return fluid 14a is returned to the tank T.

  On the other hand, from the upstream side of the second pump P2, the straight travel switching valve 16, the travel switching valve 17, the bucket switching valve 18, the boom I switching valve 19, the arm II switching valve 20, and the standby switching are provided. The valves 21 are sequentially connected, and a neutral cut valve 22 is connected to the most downstream side. These switching valves 16-21 constitute the second circuit system 23. When each switching valve 16-21 is in the neutral position as shown, its center open passage 24 is opened and the second pump P2 is opened. The fluid discharged from the tank is guided to the tank T. In addition, the code | symbol 25 is a parallel channel | path, and connects each switching valve 16-21 to the 2nd pump P2 in parallel.

A branch passage 26 is connected to the center open passage 24 between the neutral cut valve 22 located on the most downstream side and the standby switching valve 21 located immediately upstream thereof, so that the neutral cut valve 22 has a cut position. When held, the pressure fluid supplied from the second pump P2 to the center open passage 24 is supplied to another circuit system (not shown) via the branch passage 26.
Japanese Patent No. 3388799

  Since the regeneration throttle is formed in the valve body of the switching valve that controls a specific actuator that requires regeneration, there is a problem that the processing cost of the regeneration throttle is increased. The reason is as follows. is there. In the valve body of the switching valve that controls the actuator, various passages are formed and devices such as a relief valve are incorporated, so the position where the regeneration throttle can be formed is limited, and the position is also very narrow. The fact is that it has to be a difficult place. In order to form the regeneration diaphragm in such an extremely narrow portion, there is a problem that the processing cost is inevitably increased.

As a means for solving the above problem, if the regeneration throttle means is externally attached to the regeneration switching valve as in the apparatus of FIG. 6, the regeneration throttle must be formed in a narrow area. Is solved. However, in this case, another problem arises in that the entire apparatus is enlarged by the amount of the reproduction aperture.
Moreover, in the case of the current power shovel in which the regeneration throttle means is externally attached to the regeneration switching valve, as shown in FIG. 7, a useless space 27 is formed on the first circuit system 6 side. There was also a problem.
FIG. 7 is a side view of the valve block as viewed from the spool hole side, and the portions denoted by reference numerals as switching valves, regeneration throttle means or neutral cut valves indicate the end surfaces of the spool holes.
An object of the present invention is to provide a control device that does not increase the size of the entire device and does not increase the cost.

  The present invention includes a first circuit system connected to the first pump and provided with a plurality of switching valves, and a second circuit system connected to the second pump and provided with a plurality of switching valves, and at least a first circuit system. The circuit system is provided with a specific switching valve having a regeneration function for regenerating the return fluid from the specific actuator to the supply side of the specific actuator, and when the specific switching valve is switched to the regeneration position, In the second circuit system, a regeneration throttle is provided in the return side passage or a passage communicating therewith, and the return fluid is regenerated with the pressure corresponding to the pressure loss when the fluid passes through the regeneration throttle. The switching valve provided in the center valve has a center open passage for guiding the supply fluid of the second pump to the tank when they are in the neutral position. Downstream, it is to assume control device provided with a neutral cut valve for opening and closing the center opening passage.

The first invention is based on the above control device, and the neutral cut valve is constituted by a spool valve, and the neutralization cut valve is provided with the regeneration throttle, and the regeneration throttle is the neutral cut valve. It is characterized by comprising a variable throttle that makes the opening degree variable according to the switching amount of the valve.
According to a second aspect of the present invention, when the spool of the neutral cut valve is in a neutral position, the center open passage is maintained in an open state, and the regeneration throttle is maintained in a throttle state or a closed state. Is switched from the neutral position to either one, the center open passage is closed while the regeneration throttle is maintained in the throttle state or closed state, and the center valve is switched from the neutral position to the other. It is characterized in that the opening of the regeneration throttle is gradually increased in accordance with the opening of the spool valve while the open passage is kept open.

According to the first aspect, since the regeneration throttle is provided along with the neutral cut valve, the processing cost can be reduced as compared with the case where the regeneration throttle is formed on the specific switching valve as in the prior art. This is because the neutral cut valve only needs to turn on and off the center open passage, so the configuration is simpler than the switching valve for controlling the actuator, and there is sufficient space for forming the regeneration throttle. .
Further, since the regeneration throttle is configured with a variable throttle, when the return fluid is not regenerated, the return fluid can be quickly discharged by increasing the opening of the regeneration throttle. Therefore, when the return fluid is not regenerated, the pressure loss in the return passage caused by the regeneration throttle can be reduced, and the regeneration throttle does not hinder the operation of the actuator.

  According to the second invention, since the opening control of the center open passage and the regeneration throttle is performed according to the switching direction of the neutral cut valve, a completely different function of neutral cut and regeneration can be achieved with a single spool valve. Moreover, it can be realized with a simple structure.

The embodiment shown in FIGS. 1 to 5 shows a hydraulic control circuit for a power shovel that is a construction machine, and the difference from the conventional one is the connection position of the neutral cut valve 28 and its structure. Others are the same as in the prior art shown in FIG. Therefore, the same constituent elements as those in the prior art will be described using the same reference numerals as those in FIG.
The hydraulic control circuit for the power shovel shown in FIG. 1 includes a first pump P1 and a second pump P2. Then, the traveling switch valve 1, the standby switching valve 2, the turning switching valve 3, the boom II switching valve 4 and the arm I switching valve 5 are sequentially connected to the first pump P1 from the upstream side thereof. These switching valves 1 to 5 constitute a first circuit system 6. When each of these switching valves 1 to 5 is in the neutral position as shown in the drawing, the center open passage 7 is opened, and the fluid discharged from the first pump P1 is guided to the tank T via the tank passage 11. I am doing so. In addition, the code | symbol 8 is a parallel channel | path and connects each switching valve 1-5 in parallel with respect to the 1st pump P1.
The arm I switching valve 5 constitutes a specific switching valve having the regeneration function of the present invention.

A neutral cut valve 28 is connected via a regeneration passage 50 to the return passage 9 when the arm I switching valve 5 located on the most downstream side is switched to the regeneration position on the left side of the drawing. ing. The neutral cut valve 28 is provided with a regeneration throttle 29. When the neutral cut valve 28 is in the neutral position, the regeneration throttle 29 maintains the regeneration passage 50 in the throttle state. The neutral cut valve 28 maintains the center open passage 24 in the open state at the neutral position.
On the other hand, when the neutral cut valve 28 is switched to the regeneration position, which is the left side of the drawing, the center open passage 24 is closed while the opening of the regeneration throttle 29 is kept constant, and the neutral cut valve 28 is moved to the right side of the drawing. When switched, the opening of the regeneration throttle 29 is gradually increased while the center open passage 24 is kept open.

As described above, when the return passage 9 and the tank passage 11 are communicated with each other via the regeneration restrictor 29, when fluid flows from the return passage 9 to the tank T via the regeneration restrictor 29, A pressure corresponding to the pressure loss is generated.
The fluid holding the pressure in this way is supplied to the supply side passage 13 via the check valve 12 and supplied to the piston side chamber 14 a of the arm cylinder 14. That is, the return fluid from the rod side chamber 14 b of the arm cylinder 14 is regenerated to the piston side chamber 14 a of the arm cylinder 14 via the return passage 9.

In addition, when the fluid is regenerated in the piston side chamber 14a of the arm cylinder 14 as described above, the load is acting on the arm cylinder 14 in the direction of the arrow 15 while the rod of the arm cylinder 14 is extended. When performing excavation work, the load direction is reversed. For this reason, the pressure in the piston side chamber 14a rises. At this time, the check valve 12 is closed by the load pressure so that the pressure fluid from the first pump P1 does not escape to the return passage 9 side.
When the arm I switching valve 5 is switched to the right in the drawing, the supply fluid from the first pump P1 is supplied to the rod side chamber 14b of the arm cylinder 14 via the supply passage 13 and the piston side chamber. The entire amount of the return fluid 14a is returned to the tank T.

On the other hand, from the upstream side of the second pump P2, the traveling straight travel switching valve 16, the traveling switching valve 17, the bucket switching valve 18, the boom I switching valve 19, the arm II switching valve 20, and the standby switching. The valves 21 are sequentially connected, and the second circuit system 23 is configured by these switching valves 16 to 21. In addition, the center open passage 24 on the downstream side of the standby switching valve 21 communicates with the above-described neutral cut valve 28 and is also connected to the branch passage 26.
When each of the switching valves 16 to 21 is in the neutral position as shown in the figure, the center open passage 24 is opened to guide the discharge fluid from the second pump P2 to the tank T. In addition, the code | symbol 25 is a parallel channel | path, and connects each switching valve 16-21 to the 2nd pump P2 in parallel.
Further, as described above, the neutral cut valve 28 communicates the center open passage 24 with the tank T via the tank passage 11 when the neutral cut valve 28 is at the neutral position or the right position in the drawing. When switched to the left position in the drawing, the communication between the center open passage 24 and the tank passage 11 is cut off, and the pressure fluid supplied from the second pump P2 to the center open passage 24 is illustrated via the branch passage 26. Not to supply to other circuit systems.

  FIG. 2 specifically shows the arm I switching valve 5 as the regeneration switching valve and the neutral cut valve 28 connected to the switching valve 5. As shown in FIG. 2, the arm I switching valve 5 has a spool 31 incorporated in its valve body 30 in a slidable manner and the center 31 of the first circuit system 6 is opened when the spool 31 is kept in the neutral position shown in the figure. The passage 7 is kept open. When the pilot pressure is guided to the left pilot chamber 32 and the spool 31 is moved in the right direction in the drawing, the arm I switching valve 5 is switched to the regeneration position. That is, while the center open passage 7 is closed, the pressure fluid led from the first pump P1 to the parallel passage 8 is led to the supply side passage 13, and one annular formed on the spool 31 from the supply side passage 13. The gas is supplied to the piston side chamber 14 a of the arm cylinder 14 via the groove 33 and one actuator port 34.

  At this time, the return fluid from the rod side chamber 14 b of the arm I switching valve 5 is guided to the return passage 9 via the other actuator port 35 and the other annular groove 47. In the figure, reference numeral 12 denotes a check valve provided in the valve main body 30 and permits only the flow from the return passage 9 side to the supply passage 13.

On the other hand, the neutral cut valve 28 connected to the arm I switching valve 5 has a spool hole 37 formed in the valve body 36, and a spool 38 is slidably incorporated in the spool hole 37 and both ends of the spool 38 are slidably mounted. In the pilot rooms 39 and 40. In the figure, reference numeral 41 denotes a centering spring provided in the pilot chamber 40.
The valve body 36 has an inflow passage 42 communicating with the center open passage 24 of the second circuit system 23 and a flow passage 43 communicating with the return passage 9 of the arm I switching valve 5. ing. A relay annular recess 44 communicating with the tank T is formed between the inflow path 42 and the flow path 43.

  Further, the spool 38 is formed with a first annular groove 45 and a second annular recess 46, and when the spool 38 is in the neutral position shown in the figure, the inflow passage 42 and the relay annular recess via the first annular groove 45. 44 is communicated to guide the fluid flowing from the inflow path 42 to the tank T. Further, the land 48 of the spool 38 is formed with a notch 49 that constitutes the regeneration throttle 29, and when the spool 38 is in the neutral position shown in the drawing, the flow passage 43 and the relay annular recess 44 are formed through the notch 49. And the fluid flowing in from the flow passage 43 is guided to the tank T. The notch 49 has a large aperture area in the vicinity of the opening on the second annular recess 46 side.

On the other hand, when pilot pressure is introduced into the pilot chamber 39 and the spool 38 is moved in the right direction in the figure, the inflow path 42 and the first annular groove 45 are different from each other, and the communication between the inflow path 42 and the relay annular recess 44 is established. Blocked. Therefore, the center open passage 24 of the second circuit system 23 is closed, and the fluid guided to the center open passage 24 is supplied to the branch passage 26.
At this time, the flow passage 43 and the relay annular recess 44 communicate with each other via a notch 49 (regeneration throttle 29), and the communication opening degree between the flow passage 43 and the relay annular recess 44 is maintained constant. Yes. That is, the communication opening degree between the flow passage 43 and the relay annular recess 44 is kept constant within a range in which the spool 38 can move in the right direction in the drawing from the neutral position. The function of the playback diaphragm 29 is as described above.

On the other hand, when pilot pressure is introduced into the pilot chamber 40 and the spool 38 is moved in the left direction in the figure, the throttle area of the notch 49 increases, and the communication opening degree between the flow passage 43 and the relay annular recess 44 is increased. Becomes larger. When the spool 38 is further moved leftward in the figure, the second annular recess 46 gradually faces the relay annular recess 44, and the communication opening degree between the flow passage 43 and the relay annular recess 44 is further increased. That is, the communication opening degree between the return passage 9 and the tank T is increased in accordance with the switching amount at which the spool 38 switches from the neutral position to the left in the figure.
At this time, the inflow path 42 and the relay annular recess 44 communicate with each other via the first annular groove 45, and the communication opening degree between the inflow path 42 and the relay annular recess 44 is maintained constant. In other words, within a range in which the spool 38 can move to the left in the figure from the neutral position, the communication opening degree between the inflow passage 42 and the relay annular recess 44 is kept constant.

The relationship between the switching amount of the spool 38, the neutral cut area (the opening area between the inflow passage 42 and the relay annular recess 44) and the regeneration throttle area (the opening area between the flow passage 43 and the relay annular recess 44) is shown in FIG. As shown in
As is clear from this figure, in the neutral position of the spool 38, the center open passage 24 communicates with the tank, and the return passage 9 communicates with the tank in a throttled state. When the spool 38 is switched to one A direction, the center open passage 24 is blocked while the throttle amount between the return passage 9 and the tank is kept constant, and when the spool 38 is switched to the other B direction, the center open While the communication opening degree of the passage 24 is kept constant, the communication opening degree of the return passage 9 and the tank gradually increases.

  In any case, in this embodiment, the regeneration restrictor 29 is originally provided on the neutral cut valve 28 having a simple structure having only the function of communicating the inflow path 42 and the relay annular recess 44 or blocking the communication. Since it is formed, the processing itself is simplified, and the processing cost can be reduced accordingly. In addition, since the neutral cut valve 28 in this case is involved in either the first circuit system 6 or the second circuit system 23, the neutral cut valve 28 may be provided on either circuit system side. The degree of freedom increases. Therefore, as shown in FIG. 4, in the current excavator, the number of valves can be intentionally matched between the first circuit system 6 and the second circuit system 23, and a wasted space 27 as in the conventional case. Can no longer be made. 4 is a side view when viewed from the spool hole side, similarly to FIG.

The neutral cut valve 28 performs switching control by guiding pilot pressure to the pilot chambers 39 and 40. The pilot pressure guided to the pilot chamber 40 is increased by, for example, increasing the pressure in the piston side chamber 14a or the supply side passage 13. It is desirable to raise it accordingly. That is, when the pressure in the piston-side chamber 14a or the supply-side passage 13 becomes high, the opening degree of the regeneration throttle 29 is kept at the maximum for the following reason.
That is, when fluid is regenerated in the piston side chamber 14a of the arm cylinder 14, a load is applied to the arm cylinder 14 in the direction of arrow 15, but excavation work or the like is performed while the rod of the arm cylinder 14 is extended. When doing so, as already explained, the pressure in the piston side chamber 14a increases.

When the pressure in the piston side chamber 14a increases, the check valve 12 is closed, so that the return fluid from the rod side chamber 14b is not regenerated, but returned to the tank T via the return passage 9 → regeneration passage 50 → neutral cut valve 28. To do. At this time, if the opening of the regeneration throttle 29 is small, the return fluid in the rod side chamber 14b is not quickly discharged but becomes a resistance, and the arm cylinder 14 cannot be quickly expanded.
Therefore, if the opening of the regeneration restrictor 29 is increased in accordance with the pressure increase in the piston side chamber 14a on the supply side and the supply side passage 13 when the arm cylinder 14 is extended, the return fluid from the rod side chamber 14b is quickly spilled. It can be discharged and the extension of the arm cylinder 14 is not hindered. Therefore, for example, when a pressure sensor is connected to the supply side passage 13 and the pilot pressure led to the pilot chamber 40 is controlled in accordance with a signal from the pressure sensor, the regeneration throttle 29 is operated by the arm cylinder 14. It can be made unobstructed.

  In the above embodiment, when the neutral cut valve 28 is in the neutral position, the regeneration throttle 29 is maintained in the throttle state. For example, as in another embodiment shown in FIG. The diaphragm 29 may be completely closed. In this way, if the regeneration throttle 29 is completely closed, the entire return fluid can be regenerated. Further, when the regeneration throttle 29 is completely closed, it is only necessary to shorten the notch 49 so that the notch 49 does not face the relay annular recess 44 at the neutral position of the spool 38.

It is a circuit diagram. It is sectional drawing. It is a figure which shows the relationship between the switching amount of a spool, a neutral cut area, and a reproduction | regeneration aperture | diaphragm | restriction area. It is the side view which looked at the valve block from the spool hole side. It is a circuit diagram of other embodiments. It is a conventional circuit diagram. It is the conventional side view which looked at the valve block from the spool hole side.

Explanation of symbols

P1 1st pump P2 2nd pump 1-5 Switching valve 6 1st circuit system 9 Return path 11 Tank path 16-21 Switching valve 23 2nd circuit system 25 Parallel path 26 Branching path 28 Neutral cut valve 29 Reducing throttle 36 Valve Body 37 Spool hole 38 Spool

Claims (2)

  A first circuit system connected to the first pump and provided with a plurality of switching valves; a second circuit system connected to the second pump and provided with a plurality of switching valves; and at least the first circuit system A specific switching valve having a regeneration function for regenerating the return fluid from a specific actuator to the supply side of the specific actuator is provided, and when the specific switching valve is switched to the regeneration position, the return side becomes the return side. A regenerative restrictor is provided in the passage or a passage communicating therewith, and the return fluid is regenerated with the pressure corresponding to the pressure loss when the fluid passes through the regenerative restrictor, while the switching provided in the second circuit system The valves provide a center open passage for guiding the supply fluid of the second pump to the tank when they are in the neutral position, and at the most downstream of this second circuit system, In the control device provided with the neutral cut valve for opening and closing the center open passage, the neutral cut valve is constituted by a spool valve, and the regeneration restrictor is provided in addition to the neutral cut valve. A control device comprising a variable throttle that varies the opening according to the switching amount of the cut valve.   When the spool is in the neutral position, the neutral cut valve maintains the center open passage in the open state and maintains the regeneration throttle in the throttle state or the closed state. When switching to either one, the center open passage is closed while the regeneration throttle is maintained in the throttle state or closed state, and when the spool valve is switched from the neutral position to the other, the center open passage is opened. The control device according to claim 1, wherein the opening of the regeneration throttle is gradually increased in accordance with the opening of the spool valve while maintaining the state.

Images