JPS5813278A - Flow control circuit capable of joining fluid flows automatically - Google Patents

Abstract

PURPOSE:To join the flows of fluid discharged from a plurality of pumps automatically, by by-passing a circuit of pressure control valves from a main fluid passage extended between a pump and a throttle valve, connecting a circuit of other pumps and check valves to said main fluid passage, and providing pressure compensating valves in respective fluid passages branched from the passage extended between said other pumps and the check valves. CONSTITUTION:While the opening of a throttle valve 3 is small, spring pressures DELTAP1, DELTAP2, DELTAP3 of by-pass pressure compensating valves 5, 12, 16 associated respectively with a first to a third fixed displacement pumps 1, 7, 17 hold the following relationship; DELTAP1>DELTAP2>DELTAP3. Therefore, the differential pressure on the opposite sides of the throttle valve 3 is determined only by DELTAP1 and only the pump 1 is coupled operatively with a main fluid passage 4. Subsequently, when the differential pressure on the opposite sides of the valve 3 becomes lower than P2 as its opening is increased, the pump 2 is also set into operation in addition to the pump 1, so that fluid discharged from these two pumps is passed through the main fluid passage 4. Similarly, when the opening of the valve 3 is further increased, the pump 3 is also set into operation together with the pumps 1, 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is particularly suitable for use in vehicles, etc., and is an automatic merging type in which fluid discharged from a plurality of fixed pumps can be merged into an automatic fishing line according to the opening degree of a throttle valve. Regarding a flow rate control circuit.

Conventionally, in a combined flow rate control circuit, as shown in FIG. 1', for example, a check valve 8 is used to transfer the fluid discharged from a first fixed pump 2' to the fluid discharged from a second fixed pump 2'.

□ so that the combined fluid can be supplied to the throttle valve 4°, and according to the opening degree of the throttle valve 4°.
and then operate the switching valve 5° and the second
Unload or onload the fixed pump,
In addition to reducing energy loss, the relief valve 7° discharges excess fluid into the tank while the pressure reduction and expansion pressure compensation valve 8°
It is known that the differential pressure across the throttle valve 4'' is controlled to be constant.

However, this combined flow rate control circuit has the disadvantage that it is not possible to fully automatically turn on or unload the second fixed pump 2, as shown in the figure above. Operate the unload valve 6
The disadvantage is that the control system becomes complicated and expensive because it unloads or loads the signal. Also, the first condition in on-road condition. The load pressure of the second fixed pumps 1', 2' is determined by the relief valve 7 regardless of the secondary pressure of the throttle valve 49.
Since the set pressure is set to , the disadvantage is that the power loss is large.

An object of the present invention is to make the control system inexpensive and simple by automatically unloading or on-loading according to the opening degree of the second fixed pump tray throttle valve, and to make the control system inexpensive and simple. The purpose is to reduce power loss by adjusting the load pressure to a pressure corresponding to the pressure on the secondary side of the throttle valve.

In order to achieve the above object, the present invention provides a main fin between the first stationary pump and the throttle valve.

A pressure control valve is provided in the branched bypass line, and a second fixed pump is connected between the first fixed pump and the throttle valve via a line provided with a first check valve,
A pilot chamber is connected to the bypass line branched from between the second fixed pump and the first check valve on the downstream side of the first check valve, and an error valve is used to prevent backflow, and the bypass type pressure compensation valve is opened. On the other hand, when the opening of the throttle valve is more than one foot, the bypass type pressure compensating valve is automatically operated to adjust the pressure of the throttle valve to the pressure corresponding to the spring pressure. The first check valve is opened so that the differential pressure before and after the check valve can be controlled. The discharge fluids of the second fixed pump are combined, and the fluids discharged from the first fixed pump are combined.
It is characterized in that the combined load pressure of the second fixed pump is controlled to a pressure that corresponds to the secondary pressure of the throttle valve, thereby saving energy.

Hereinafter, the present invention will be explained in detail with reference to the illustrated embodiments.

In Fig. 2, 1 is the first fixed pump, 2 and 8 are the decompression expansion pressure compensation valves and throttle valves that are sequentially provided from the upstream side on the main line 4 connected to the first fixed pump 1, and 5 is the first fixed pump 1. A first bivanu pressure compensation valve as an example of a pressure control valve provided in a bypass line 6 branched from the main line 4 between the decompression expansion pressure compensation valve 2, 7 a second fixed pump,
Reference numeral 8 designates a first check valve provided in the line 11 connecting the second fixed pump 7 and the main line 4 upstream of the decompression and expansion pressure compensation valve 2, and reference numeral 12 designates the second fixed pump 7 and the first check valve 8. As soon as the bypass line 9 branched from between
A bypass type pressure compensation valve, 18 is an eighth fixed pump, and 14 is a second valve provided in a line 15 connecting the eighth fixed pump 18 and the main line 4 upstream of the decompression expansion pressure compensation valve 2.
The check valve 16 is a third bypass type pressure compensating valve branched from between the eighth solid pump 18 and the second check valve 14 and provided in the ninth pipeline 17, which is connected to the first and second check valves.
Each spring chamber 2 of the 8th pie-vanu type pressure compensation valve 5, 12.16
5, 26, and 27 are connected to the downstream side of the throttle valve 8, respectively, and the first pie valve type pressure compensation valve 5 converts the differential pressure between the upstream side of the pressure reduction type pressure compensation and the downstream side of the throttle valve 8 into the spring chamber 25. spring 81
．． The second bypass bus type pressure compensating valve 12 converts the above differential pressure into the spring pressure ΔP of the spring 82 of the spring chamber 26.
2, the eighth bypass type pressure compensating valve 16 can control the differential pressure to the spring pressure of the spring 88 of the spring chamber 27, ΔP8.

Each of the above spring pressures △Pt, △P2. The relationship of △P8 is (△P
〉△P2>△P8). For example, △P1=1
04I/d, △P2==8 immediately/d, △P8=64'/d
Set to . The spring pressure ΔPo of the spring 86 of the spring chamber 85 of the decompression expansion pressure compensation valve 2 is set smaller than the spring pressure ΔP8 of the eighth bypass type pressure compensation valve 16. For example, ΔPo=8Po is connected to the line 11 downstream of the first check valve 8 via the pilot line 22, and the pilot chamber 28 of the eighth bypass type pressure compensation valve 16 is connected to the pilot line 22.
4, the second check valve 14 is also connected to the downstream line 1.
Connect to 5.

The automatic merging type flow control circuit configured as described above operates as follows.

It is now assumed that the opening degree of the throttle valve 8 is set to a constant value less than or equal to the opening degree x2 in FIG.

At this moment, the first pressure compensator 5 discharges the surplus fluid from the bypass line 6, and the differential pressure between the upstream side of the decompression expansion pressure compensating valve 2 and the downstream side of the throttle valve 8 becomes the spring pressure △P1. The second bypass type pressure compensating valve 12 discharges the excess fluid from between the second fixed pump 7 and the first check valve 8 to the tank through the bypass line 9, thereby reducing the differential pressure to the spring pressure ΔP2. The eighth bypass type pressure compensation valve 13 transfers excess fluid to the eighth fixed pump 18 and the second check.
,)□ It is attempted to control the differential pressure to the spring pressure ΔP8 by discharging it to the tank from between the valve 14 and the bypass through the in 17. At point 2, the opening degree of throttle valve 8 is small and 8P
Since 0〉△P2〉△P8, the required flow rate for the throttle valve 8 is only the discharge flow rate of the first fixed pump l, and therefore the first bypass type pressure compensating valve 5 is able to maintain the above differential pressure △P1. Control, the ninth 1st. The second check valves 8 and 14 are respectively closed when the pressure difference across them is k. Note that the decompression expansion pressure compensation valve 2 controls the differential pressure before and after the throttle valve 8 to the spring pressure ΔPo.

On the other hand, at this time, the pressure on the upstream side of the decompression expansion pressure compensation valve 2 and the pressure on the downstream side of the throttle valve 8 are transmitted to the pilot chamber 21 and the spring chamber 26 of the second bypass type pressure compensation valve 12, respectively. It is being Therefore, the pressure difference between the pilot chamber 21 and the spring chamber 26 becomes ΔP0, which is greater than the spring pressure ΔP, and the second bypass type pressure compensation valve 12 is completely opened and stands still. Therefore, the second fixed pump 7 is in an unloaded state. 1! Similarly, the eighth bypass type pressure compensation valve 16 (D, ; As a result, the pressure difference between the pilot chamber 28 and the spring chamber 27 becomes ΔP0, which is larger than the spring pressure ΔP.Therefore, the third bypass type pressure compensation valve 16 is completely opened. Then, the eighth stationary pump 18 comes to an unloaded state.

Therefore, when the opening degree of the throttle valve 8 is less than or equal to x2 in FIG. In addition to unloading the eighth fixed pump 7゜18, the load pressure of the first fixed pump l is reduced to the throttle valve 8.
Since the pressure is controlled to be higher than the secondary pressure by the spring pressure P according to the secondary pressure, this automatic merging type flow control circuit maintains the fixed pump load pressure regardless of the secondary pressure of the throttle valve. The power loss is lower than that of a combined flow rate control circuit that provides the set pressure for the relief valve.

Next, the opening degree of the throttle valve 8 is determined as shown in FIG. IX2) will also be increased. In this case, with the Q discharged fluid only from the first fixed den l, the differential pressure between the upstream side of the pressure compensating valve 2 and the downstream side of the throttle valve 8 can be reduced even if the bypass type pressure compensating valve 5 is completely closed. , 5ΔP1'. As the opening degree of the throttle valve 8 is further increased, the differential pressure decreases accordingly, and when the opening degree of the throttle valve 8 reaches S in FIG. 8, the differential pressure becomes ΔP2. Generally, the opening degree X2÷S or i, which is slightly 52, is considered to be larger.

Suppose that the transition region from when the opening degree changes from X to S has passed and it has become slightly larger than 52.

In this case, the discharge flow rate from the first fixed pump l alone will be insufficient, and the differential pressure between the upstream side of the decompression expansion pressure compensation valve 2 and the downstream side of the throttle valve 8 will become smaller than △P2.
At this time, the second bypass type pressure compensating valve 12 opens and closes so that the differential pressure becomes the spring pressure ΔP2, so the second fixed pump 7 is automatically on-loaded and the discharged fluid is transferred to the first check valve. 8 to join the fluid from the first stationary pump l. This combined fluid passes through the decompression and expansion pressure compensation valve 2 and is supplied to the throttle valve 8. The above-mentioned pressure reduction and expansion pressure compensation valve 2
The differential pressure before and after the throttle valve 8 is the spring pressure △P.

The force d controlled to
．． The second fixed pump 1.7 is on-loaded, and the differential pressure between the upstream side of the decompression expansion pressure compensation valve 2 and the downstream side of the throttle valve 8 is controlled to spring pressure △P2 by the second bypass type pressure compensation valve 12. I will win. Therefore, since the load pressure of the first and second fixed pumps 1.7 is (secondary pressure + ΔP2), this combined flow rate control circuit is more energy efficient than the conventional combined type circuit. Moreover, at this time, the first bypass type pressure compensation valve 3 is closed because its spring pressure ΔP is larger than the differential pressure ΔP2. Further, the eighth bypass type pressure compensation valve 16 is open and stationary because its spring pressure ΔP8 is smaller than the differential pressure ΔP2. Therefore, the eighth stationary pump 18 is in an unloaded state.

Next, the opening degree of the throttle valve 8 is further increased to
Make it larger than 3.

Then, the first. Since the flow rate from only the second fixed pump 1.7 is insufficient for the throttle compensation, the differential pressure between the upstream side of the decompression expansion pressure compensation valve 2 and the downstream side of the throttle valve 8 is △
It becomes lower than P2. Then, as the opening degree of the throttle valve 3 is further increased, the above-mentioned differential pressure decreases accordingly, and when the opening degree of the throttle valve 3 reaches 88 in FIG.
It becomes 8.

Even in the transient region where this opening degree is from x8 to S8, the first
．． The second fixed pumps 1 and 7 are in the on-load state, and the eighth
The stationary pump 13 is in an unloaded state.

Next, the opening degree of the throttle valve 8 is made larger than 88 in FIG.

Then, the pressure difference between the upstream side of the decompression expansion pressure compensation valve 2 and the downstream side of the throttle valve 8 tends to become smaller than △P8.
The eighth bypass type pressure compensation valve 16 converts the above differential pressure into spring pressure △P
8, the eighth fixed pump 18
is automatically on-loaded, and its discharge fluid passes through the second check valve 14 to the first check valve 14. It joins the discharge fluid from the second [i1 constant pump 1.7. So, at this time, the first. Second. Eighth fixed pump 1. '7.18, all of them are in the on-load state, and the eighth bypass type pressure compensation valve 16 controls the differential pressure between the upstream side of the pressure reduction expansion pressure compensation valve 2 and the downstream side of the throttle valve 8 to △P8. In the evening, the pressure reduction turgor force compensation valve 2 is the throttle valve 3
The differential pressure before and after is controlled by △P and K. Also, the second.
The third bypass valve 5.12 is both closed.

In this way, this automatic merging type flow control circuit has the throttle valve 8
In response to an increase in the opening degree of the first. Second. Third fixed pump 1
．． 7.11 will be automatically loaded one after another.

Conversely, if the opening degree of the throttle valve 8 is decreased, as can be easily seen, the 8th degree second degree. First fixed pump 1B, 7.1
are automatically unloaded in sequence. Area A1 in Figure 8
causes the first stationary pump 1 to be on-loaded, and the area A2 is
゜The second solid foot pump 1.7i is on-loaded, and the first solid foot pump is loaded into the area. Second. 8th stationary pump 1, 7.18t-onload.

In the above embodiment, the throttle valve 3 is
Since the differential pressure before and after the throttle valve 8 is always controlled to be constant, the output flow rate of the throttle valve 8 becomes a curve approximately proportional to the opening degree of the throttle valve 8, as shown by a curve Q in FIG. However, if the decompression expansion pressure compensation valve 2 is removed, the above-mentioned transient region clearly appears as shown by curve B in FIG. 3, and a section where the output flow rate of the throttle valve 3 does not increase occurs.

In the above embodiment, a thread consisting of the eighth fixed pump 7, the eighth pipe-type pressure compensation valve 16, and the second check valve 14 is added, but this may be omitted. A plurality of threads including eight or more valves and check valves may be provided. Further, as shown in FIG. 4, the pressure control valve 5 may be the first bypass type pressure compensating valve 5 of FIG. Incidentally, an unloading pilot valve 40 for fully automatically unloading the second fixed pump 7 during overload pressure control is shown in FIG. That is, in FIG. 4, the second fixed pump is automatically loaded and unloaded in both flow rate control and pressure control. Above, that is,
A circuit including a first fixed pump, a bypass path, a pressure control valve, a throttle valve, a second fixed pump, a bypass type pressure compensation valve for the second fixed pump, and a first check valve, and connecting them as described above, All fall within the scope of the present invention. In this invention, the concept of the throttle valve includes a throttle switching valve with a load pressure detection boat.

As is clear from the above description, according to the present invention, a pressure control valve is provided in the bypass line branched from between the first fixed pump and the throttle valve, and the second fixed pump is connected to the first fixed pump.
2 are connected between the first fixed pump and the throttle valve via a line provided with a check valve, and a pilot chamber is connected to a bypass line branched from between the second fixed pump and the first check valve. The first check valve is connected to the downstream side of the first check valve to control the differential pressure across the throttle valve to a constant value. The second stationary pump can be automatically unloaded and loaded, so the control system can be made simple and inexpensive, and the first fixed pump can be automatically unloaded and loaded. 2nd fixed ``°''-do shaped chopsticks □
,! The 0 so 0 confluence load pressure becomes a pressure corresponding to the secondary side pressure of the throttle valve due to the body movement of the bi-vacuum type pressure compensation valve, and power loss can be reduced.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional merging type flow control circuit, Fig. 2 is a circuit diagram of an automatic merging type flow control circuit according to an embodiment of the present invention, and Fig. 8 is a circuit diagram of a throttle valve shown in Fig. 2. A graph showing the relationship between the opening degree and the output flow rate, FIG. 4, is another example. l...first fixed pump, 8...throttle valve, 5...
・First bypass type pressure compensation valve, 7... Second fixed pump, 8... First check valve, 12... Second bypass type pressure compensation valve. Patent applicant: Daikin Industries, Ltd. Representative: Patent attorney: Aobai Ao and two others 1.:::. II2■

Claims (2)

[Claims] (1) A pressure control valve (5) is provided in a bypass line branched from the main line between the first fixed pump (1) and the throttle valve (8), and a second fixed pump 7''(7)'fr
: Connected between the first fixed pump (1) and the throttle valve (8) via a line with a first check valve (8) interposed therein; The bypass line branched from between (8) and the pilot room (21
) A bypass type pressure compensation valve (2) is provided which is connected to the downstream side of all the first check valves (8) and can control the differential pressure across the throttle valve (3) at a constant level. Automatic merging type flow control circuit. (2) A third fixed pump (to) is connected between the first fixed pump (1) and the throttle valve (8) via a line in which a second check valve α4 is interposed; fixed pump a
The pilot chamber (28) is connected to the bypass line branched from between the throttle valve (3) and the second check valve α◆ on the downstream side of the second check valve α◆ to maintain a constant differential pressure across the throttle valve (3). An eighth bypass type pressure compensation valve α which can be controlled is provided, and the spring pressure of the spring chamber of the eighth bypass type pressure compensation valve α is controlled by a second bypass type pressure compensation valve α.
A patented flow control circuit characterized in that the spring pressure is set lower than the spring pressure of the spring chamber of the bypass type pressure compensation valve (2).