JPS5874903A - Confluence circuit for fluid pressure driver - Google Patents

Abstract

PURPOSE:To reduce the size and cost of a fluid pressure driver, by composing a confluence circuit of a check valve, a pilot valve, etc. CONSTITUTION:In a check valve 55, a poppet 59 is put in contact with a valve seat 60 by a spring 58 in a spring chamber 57 to disconnect a primary port 61 and a secondary port 62 from each other. The poppet 59 is stepped at the tip so that the pressure at the primary port 61 and that at the secondary port 62 are both applied to the poppet. The primary port 61 is connected to the pumping line 2 of a pump 1 through a passage 63. The secondary port 62 is connected to the pumping line 13 of a pump 12 through a passage 64. The spring chamber 57 is connected to a pilot valve 56 through a passage 65. The secondary port of a shuttle valve 67 for selecting the higher pressure side of pilot chambers 43, 44 of a changeover valve 4 is connected to a pilot chamber 66 at one end of the pilot valve 56. The secondary port of another shuttle valve 69 for selecting the higher pressure side of pilot chambers 33, 34 of another changeover valve 15 is connected to a pilot chamber 68 at the other end of the pilot valve 56.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a merging circuit for a fluid pressure drive device in which actuators are connected to two or more pumps through respective switching valves.

For example, a hydraulic excavator as shown in FIG. 1 is equipped with this type of merging circuit. This one consists of a switching valve (4) connected to the pump line (2) of the variable displacement pump (1), a switching valve (4) connected to the arm actuation cylinder (3), and a switching valve (4) connected to the left travel hydraulic motor (5). 6), A switching valve (8) connected to a swing hydraulic motor (7) and a boom merging switching valve (9) are connected in parallel, and a variable displacement pump (1) and a fixed displacement type are connected to the prime mover 0υ. The pump line of the variable displacement pump α2 that is driven simultaneously with the pump OI (13 is the switching valve 0511 to which the cylinder DI for boom operation is connected; the switching valve αη to which the hydraulic motor QQ for right travel is connected; the cylinder for packet operation (11 The switching valves H connected to the arm merging switching valves (4) and (6) are connected in parallel.
)t (8) is the corresponding pilot operated valve Qυ,
@, (c) also allows switching valves (15), 07),
(11 is the corresponding pilot operated valve c24J,
(c) With @, the pilot pressure from the pump α1 is guided to the pilot chamber of the switching valve for switching. On the other hand, the actuator boat of the boom merging switching valve (9) is connected to the switching valve a! by the flow path @# (c). 19 and cylinder α4, connect to OI, and connect the pilot chamber Gυ#03 of the boom merging switching valve (9) to the pilot chamber (to) of the switching valve Q9, )t
In addition, the actuator boat of the arm merging switching valve ■ is connected to the flow path C (I , (
40, and the pilot chamber (4υ, (4) of the arm merging switching valve ■ and the pilot chamber of the switching valve (4)
43, (44) are connected through the passage (4) (c) to form a confluence circuit. In addition, each pilot pressure from each pilot operating valve is connected to the pump (1) via a check valve.
) or (regulator (52) that controls the amount of tilting of (13)
or (to). Now, if the operating lever (47) of the pilot operating valve Qυ is operated, for example, to the right from the neutral position, the pressure reducing valve (4 lobes) will operate and connect the discharge passage θ1 of the pump α1 to the pilot passage (to).
Pump (IQ) The main pilot pressure is in the pilot chamber (4
4 and (4), switching valves (4) and (2) are both switched to position A.

Therefore, the pump line (2), the switching valve (4), the flow path OI
The fluid from the pump (1) flowing through the pump line a~
, the switching valve (2), and the flow path 07), the fluid from the pump Q2 joins the flow path C11f and flows into the cylinder (3).

'Similarly, operate the pilot operating valve (material) to operate, for example, the pressure reducing valve 6υ, and guide the pilot pressure from the pump Ql to the pilot chamber (material) of the switching valve α- and the pilot chamber CI3 of the switching valve (9). , switching valve (t!9t (9)) to position A, the pump line (131, switching valve a
9. The fluid discharged from pump a3 flowing through the flow path (to), the pump line (2), the switching valve (9), and the fluid from pump (1) flowing through the flow path (to) join together at the flow path (to). and flows into cylinder I.

However, the merging circuit includes two merging switching valves (9),
(21) and four flow paths connecting these switching valves to the actuator are required, which has the drawback of increasing the size of the device and increasing cost.

In view of the above points, the present invention aims to reduce the size and cost of the device by creating a compact merging circuit using a check valve, a pilot valve, etc. that are even smaller than the merging switching valve. .

Embodiments of the present invention will be described below with reference to the drawings. In Figure 2, the pump line (2) of the variable displacement pump (1)
is a switching valve (4) connected to an arm actuation cylinder (3).
), a switching valve connected to a left-hand hydraulic motor (not shown) (
6), a switching valve (8) connected to a swing hydraulic motor (not shown) is connected in parallel, and a variable displacement pump (1) and a constant displacement pump Ql are driven by a prime mover aυ. Pump line 0 of pump a3 has a switching valve (15+) connected to cylinder I for boom operation, and a hydraulic motor for right travel (
The switching valve surface connected to the switching valve (not shown) and the switching valve 4 connected to the packet actuation cylinder (not shown) are connected in parallel, and the switching valve (4) is controlled by the pilot operated valve Qυ, The pilot operated valve is designed to guide the pilot pressure from pump 01 into the pilot chamber of the switching valve for switching, and the switching valves (6), (8), α
η, (II is also pilot operated and switched by a pilot operated valve (not shown) having the same configuration as valve C19.In addition, the pilot pressure at that time is controlled via a check valve at the same time as switching the switching valve. The switching valve is connected to regulator a2 or eel of pump +0 or a on the switching side to control the amount of pump tilting.

The above configuration is the same as the conventional device shown in FIG.

By the way, the merging circuit of this embodiment uses a check valve (to) and a pilot valve (to) which are much smaller than the merging switching valves shown in FIG. 15 check valves are
Due to the spring gloss of the spring chamber 67), the value of 15) is lowered to the valve seat.
69 has a stepped tip so that both the pressure of the primary port 11) and the secondary port 13 are applied. I have to. The primary boat 11) is connected to the pump line (2) of the pump (1) by a channel I3, and the secondary boat 13 is connected to the pump line 0 of the pump (13) by a channel I3.
The spring chamber 6η is connected to the flow path 151 to the pilot valve K. This pilot valve has a pilot chamber (43,
(Shuttle valve 1 to select the high pressure side of 441) is connected to the pilot chamber branch at the other end of the switching valve 051 (pilot chamber (to), shuttle valve to select the high pressure side of (foundation) In the switching position, the pump line on the switching side is connected to the flow path by applying pressure to the secondary boat (4), and in the neutral position, the pump line (2) is connected to the flow path.

The high pressure side of 03 is selected by shuttle valve σ and connected to flow path 65)K.

FIG. 3 shows another embodiment of the invention.

In this embodiment, the configuration other than the merging circuit is the same as the embodiment shown in FIG. 2, so parts corresponding to those shown in FIG. 2 are designated by the same reference numerals, and redundant explanation will be omitted.

In place of the merging switching valve shown in Fig. 1, the merging circuit shown in Fig. 3 includes two check valves aυ, which are much smaller than the merging switching valve shown in Fig. 1.
σ and two 2-position 3-boat pilot valves ff3. υ
→ is used. The primary port (c) of the check valve ffυ is connected to the pump line 03 of the variable displacement pump a3 through the flow path ffQ, and the secondary port ffη is connected to the pump line (2) of the variable displacement pump (1) through the flow path ffl. , the spring chamber σ
The wound is connected to the pilot valve 0 through the flow path ■. This pilot valve is a pilot chamber (c) of a switching valve (4),
(44) f) The spring chamber 6 is switched by the pilot pressure on the high pressure side selected by the shuttle valve 6η! J
is connected to the pump line (2) of the pump (1), and when there is no pilot pressure, the spring chamber ffl is connected to the primary boat σ. Primary boat with check valve a @0
is the flow path @3. The secondary boat (c) is connected to the pump line (2) of ff1l (connected to the pump line (2) of 11),
σe connects the pump az pump line (13),
The spring chamber inlet is connected to the pilot valve ff4) by a flow path. This pilot valve switches the spring chamber (c) to the pump line (131) of the pump Q5 by switching with the pilot pressure on the high pressure side selected by the shuttle valve 1 among the pilot chamber (to) of the switching valve 051. This connects the spring chamber @9 to the primary baud (81) when there is no pilot pressure.

Next, the operation of the confluence circuit according to this embodiment will be explained.

In Fig. 2, when the pilot operating valve Qυ, (2) is in the neutral state shown, the discharge pressure of the high pressure side pump (1) * (2) of the shuttle valve σ is applied to the spring chamber 6η of the six check valves. [Since this pressure and the force of pushing the poppet due to the spring (to) are larger than the push-up force of the poppet due to the discharge pressure of the pump (1) and (121) acting on the tip of the poppet 69, the poppet 15I is in contact with the valve seat -.Now, if the operating lever (47) of the pilot operating valve (21) is operated, for example, to the right from the neutral position shown in the figure, the pressure reducing valve (c) will operate and the discharge passage of the pump (II) will be operated. (to) is connected to the pilot passage -, so the pilot pressure is between the pilot chamber θa of the switching valve (4) and the shuttle valve I.
The switching valve (4) and the pilot valve (to) are both at position A.
The spring chamber 6 of the check valve 65) is switched to ? ) is affected by the discharge pressure of the pump (1). At the same time, the pilot pressure is applied to pump (1) and (J2) via the check valve.
) to the regulator "63. (to), which increases the amount of tilting of the pump. Therefore, the check valve-01 primary port 6υ and the spring chamber No. 6 are at the same pressure. On the other hand, the secondary port I3
Since the pressure of pump a3 is guided to , the secondary baud)
13 pressure is spring chamber 6? ), i.e., the pressure of the pump (1
) and the force of the spring (to), the poppet 6 wound opens and the fluid from pump az flows into the secondary po) 13
The primary boat enters the pump line (2) via the flow path, merges with the fluid from the pump (1), and enters the switching valve (4).
) flows to Siciling (3). At this time, the backflow from the poppet (5gl is pressed against the valve seat and the primary boat I]) to the secondary boat I21 is In other words, in this case, the five check valves act as normal check valves.If the operating lever (4?) of the pilot operating valve (20) is returned to the neutral position, the pilot chamber (44? ) 96119 disappears, the switching valve (4) and the pilot valve (to) return to the neutral position by the internal spring, and the cylinder (3) stops operating.Meanwhile, Since the pressure of either the pump line (2) or (13), which is higher, is guided by the shuttle valve (7) to the spring chamber 61 of the check valve 69, the poppet 6 is closed and the primary boat 6υ and the secondary Bo) Cut off communication with 13.

Next, pilot operated valve c! When the operation lever of the pump is operated, for example, to the right from the neutral position shown in the figure, the pressure reducing valve 6υ is activated, and the discharge passage (41) of the pump OI is connected to the pilot passage (c).
Since the pilot pressure is connected to the pilot chamber of the pilot valve 09 and the pilot chamber of the pilot valve trowel via the shuttle valve 4, the pilot pressure acts on the pilot chamber of the pilot valve α9 and the pilot valve (5).
e are both switched to position B, and the discharge pressure of the pump (12+) acts on the spring chamber 67) of the check valve 551. At the same time, this pilot pressure is applied to the pump 02) and the regulator (1) via the check valve. 631. (The spring chamber 67 of the check valve 651) and the secondary bow) I2 become the same pressure, while the primary bow) If) has the same pressure as the discharge of the pump (1). Since the pressure is guided, the pressure at the primary port is the spring chamber 6η.
, that is, the sum of the pressure of pump 02 and the force of spring 6υ, 151 opens and the fluid from pump (1) flows from the primary boat τ) 11) to the secondary boat and the flow path. The fluid then enters the pump line Q31, joins the fluid from the pump a, and flows through the switching valve (IJ) to the cylinder a4.

At this time, if the pressure of the primary boat 6υ is lower than the pressure of the secondary boat 12, the backflow from the poppet (5I is pressed against the valve seat ■ and the secondary boat) 11 to the primary boat υ does not occur. do not have.

Next, the operation of the merging circuit shown in FIG. 6 will be explained. In the figure, in the illustrated state where the operating lever (4η, (87)) of the pilot operated valve Qυ, C) 4) is in the neutral position; the spring chamber σ of the check valve ffυ is in the pump (+
The discharge pressure of pump (1) is guided to the spring chamber (c) of check valve a3. Therefore, the push-up side pressure (primary port pressure) of the check valve συ, 621 and the push-side pressure (spring chamber pressure) are not the same pressure, and the poppet a3. Both a:l are in contact with the spring -, (9υ valve seat 614), and I51, and the valve is closed. Now, when the operating lever (4η) is operated, for example, to the right from the neutral position shown in the figure, the pressure reducing valve (48) is activated and connects the discharge passage (41) of the pump OI to the pilot passage (to), so the pilot pressure is changed to the switching valve (4). The switching valve (4) and the pilot valve σj are switched to position B, and the check valve σj is switched to the position B. The discharge pressure of the pump (1) acts on the spring chamber ffl of aυ.At the same time, this pilot pressure is led to the pump (11) and the regulators 52 and 63 of a through the check valve, and controls the amount of pump displacement. (921 is opened, and fluid from the pump (1) flows from the primary boat Cl5 through the secondary port σD1 channel ff into the pump line (2), and the fluid from the pump (1) flows into the pump line (2) through the secondary port
) and passes through the switching valve (4) into the cylinder (
3). At this time, the pressure of the primary boat σ9 is 2
If the pressure is lower than the pressure of the secondary boat ση, the poppet (93 is closed) prevents the backflow from the secondary boat ση to the primary boat (Cl5). On the other hand, the check valve σ is the pilot valve ff4
is in the position shown, the pressure in the primary boat @D and the spring chamber - is the same, and the poppet (93 is in contact with the valve seat (E) by the spring aυ.Here, the operating lever +47) is moved to the neutral position. When the pilot pressure is returned, the pilot pressure disappears and the switching valve (4) returns to the neutral position, the cylinder (3) stops operating, and the pilot valves ff and 11 switch to position A, causing the spring chamber σ damage to the pump 03. Since the discharge pressure is guided, the spring chamber ffl and the primary bow) ff! The pressure becomes the same, and the boppet (93) comes into contact with the valve seat due to the spring wire.

In addition, when the operating lever @η of the pilot operating valve (24) is operated from the neutral position shown in the figure, for example, to the left, the pressure reducing valve (t)
is activated and the discharge passage O1 of pump a1 is connected to the pilot passage (
Since the pilot pressure is connected to the pilot chamber (not shown) of the switching valve O5 and the pilot chamber (not shown) of the pilot valve σ through the shuttle valve is switched to position B, check valve f
The discharge pressure of pump 0δ acts on the spring type can f3. At the same time, this pilot pressure is introduced to the pump αa and the regulator (53, 62) of (1) via the check valve to increase the pump displacement amount. In this case, the pump (1
) The poppet pushing force due to the pressure of the primary boat @D communicating with the spring 0υ is greater than the force pushing the poppet due to the pressure of the spring type can, that is, the discharge pressure of the pump a, the poppet (
93 opens, and fluid from the pump (1) flows from the primary port to the secondary boat, through the flow path, fff9-, into the pump line (3), and merges with the fluid from pump a3. It flows to cylinder I through switching valve QS.

At this time, if the pressure in the primary boat @D is lower than the pressure in the secondary boat (c), the poppet 6) 3 closes to prevent backflow from the secondary boat can to the primary boat (c). On the other hand, in the check valve ffυ, since the pilot valve ff3 is in the illustrated position, the primary port 4 and the spring chamber ffl are at the same pressure, and the spring chamber is in contact with the valve seat. When the operating lever is returned to the neutral position, the pilot pressure disappears, the switching valve (15) returns to the neutral position, and the cylinder I stops operating.

On the other hand, the pilot valve ff4) switches to position A and guides the discharge pressure of the pump (1) to the spring chamber (to), so the primary boat @D and the spring type can have the same pressure, and the poppet (to) aD] comes into contact with the valve seat (E).

As explained above, in the present invention, one pump has one
A confluence circuit is constructed using a small check valve that connects the secondary port to the other pump, and a pilot valve that selectively guides the discharge pressure of both pumps to the spring chamber of this check valve. The two large merging switching valves and the four flow paths connecting the two merging switching valves to the actuator are no longer required, making the device more compact and reducing costs. It has the effect of

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram of a conventional device, and FIGS. 2 and 3 are hydraulic circuit diagrams each showing an embodiment of the present invention. 1.12... Variable displacement pump, 3... Arm actuation cylinder, 4, 6.8, 15, 17.19... Switching valve, 10... Fixed displacement pump, 14... Boom actuation cylinder, 21.24... Pilot operation valve, 48
, 51.96...Pressure reducing valve, 52.53...Regulator, 55- 71-72...Check valve, 56,
73,74...Pilot valve, 57°79.85...
・Spring chamber, 61, 75, 81...1st bow), 62,
77.83...Secondary boat, 67.69,70...
Shuttle valve. Patent applicant: Kawasaki Heavy Industries, Ltd. - Company style Tamaki: 1 Patent attorney: Ta 1) Shizuku (

Claims (2)

[Claims] 1. In a fluid pressure drive system in which an actuator is connected to two pumps through switching valves, at least one check valve is connected to the primary port to one pump, and the secondary port to the other pump. , is installed in the middle of the flow path that connects the discharge lines of the two pumps, detects the merging signal, automatically connects the spring chamber of the check valve with the secondary port, and detects the merging signal. A merging circuit for a fluid pressure drive device, characterized in that a pilot valve is provided that communicates the spring chamber of the check valve with the primary boat when the check valve is not in operation. 2. In a fluid pressure drive system in which an actuator is connected to two pumps through switching valves, one check valve connects the primary boat to one pump, the secondary port to the other pump, and the two pumps. a 3-position pilot valve that is interposed in the middle of a flow path connecting the discharge lines of the two pumps and connects the pump discharge lines that automatically merge upon detection of a merge signal to the spring chamber of the check valve; and a shuttle valve that detects the higher pressure of the two pumps when the pilot valve is in the neutral position and guides this pressure to the spring chamber of the check valve. confluence circuit.