JPS59194086A - Two stage pump - Google Patents

Abstract

PURPOSE:To prevent oil leakage by forming a plurality of plunger holes in the cylinder block of a high pressure pump then coupling a delivery valve to said plunger hole while forming a circular path communicating with the delivery port. CONSTITUTION:A plurality of plunger holes 15 are formed in the cylinder block of a high pressure pump then a suction valve 17 and a delivery valve 18 are coupled respectively to the tip and side of said plunger hole 15 while a circular path 19 communicating with the delivery valve 17 is formed in said cylinder block 14 and coupled to the delivery path 21. Since no piping is required for the delivery path or the high pressure path of the high pressure pump, leakage of piping can be prevented completely.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-stage pump including a high-pressure pump and a low-pressure pump.

(Conventional Two-Stage Pump) A general circuit diagram of this type of pump is shown in FIG.

In FIG. 8, a high pressure pump H and a low pressure pump L are connected and a motor M is driven to operate both pumps.

The high-pressure pump H communicates with a directional control valve 3 via a high-pressure passage 2 provided with a check valve 1 . Also,
The low pressure pump L is connected to a low pressure passage 5 provided with a check valve 4;
．． 4, it merges with the high pressure passage.

In the low pressure passage 5 connected to the low pressure pump L in this way, a low pressure relief valve 6 and an unload valve 7 are connected upstream of the check valve 4.

In FIG. 8, reference numeral 8 denotes a high pressure relief valve, which communicates with the high pressure passage 2 on the downstream side of the check valve 1.

In the circuit configuration as described above, the high pressure passage is
It was connected with a joint etc. However, the piping assembly requires skill and cannot be easily assembled by unskilled persons. In addition, because of the use of joints, oil sometimes leaked from the joints.

Moreover, when repairing, it is necessary to disassemble the piping joint first. If this disassembly is repeated many times, the sealing performance of the joint becomes extremely poor, resulting in increased oil leakage.

(Objective of the Present Invention) An object of the present invention is to provide a two-stage pump that does not use a joint in a high-pressure passage, simplifies assembly, and prevents oil leakage.

(Embodiment of the present invention) As shown in FIG. 1, a high-pressure pump H and a low-pressure pump L are installed in a tank 9, and a motor M and a directional control valve C are installed on the outer upper surface of the tank 9. and.

In the high-pressure pump H, the drive shaft 11 supported by the bearing of the casing 10 is directly connected to the swash plate 12, and the connecting shaft 13 provided on the swash plate 12 is supported by the cylinder block 14. There is. A plurality of plunger holes 15 are formed in the cylinder block 14, and a plunger 16 is slidably inserted into the plunger holes 15.

A suction valve 17 is provided at the tip of the plunger hole 15.
and a discharge valve I8 is connected to the side.

Each of the suction valves 17 is connected to a first annular passage 19 formed outside the periphery of the connecting shaft 13, and is configured to suck oil from the first annular passage.

Further, each of the discharge valves 18 has a plunger hole 15.
connected to a second annular passage 20 formed outwardly of the
High pressure oil is discharged into the annular passage 20.

The second annular passage 20 has its cylindrical portion connected to the discharge passage 21.
In addition, as shown in FIG. 4, a high pressure relief valve 22 is connected at other locations.

Note that the discharge valve 18 functions as a check valve in FIG. 7, and the second annular passage 20 and the discharge passage 21 constitute a high pressure passage a in FIG. 7.

As shown in FIG. 5, an unload valve 23 is connected to the first annular passage 19, and the configuration of the unload valve 23 is as follows.

That is, the unload valve 23 has a poppet 24,
Plunger! 6, a pilot piston 26, and a plug 27.

The plug 27 is provided to close the hole into which the pilot piston 26 is slidably inserted. When the pressure inside the second annular passage 20 exceeds the set pressure, the pilot piston 26 moves the poppet 2 under the action of the pressure.
Press 4 to perform the function of forcibly opening the poppet 24.

When the poppet 24 opens due to pressure in the second annular passage 20, the oil in the first annular passage 19 passes through the flow hole 28 formed in the poppet 24, pushes the valve 25 open, and flows into the tank 9. return.

Note that when the poppet 24 opens, the valve 25 opens the first valve 25.
This is to prevent the inside of the annular passage 18 from reaching tank pressure and to improve the suction performance of the plunger 16.

The connecting shaft 13 of the high-pressure pump H as described above is directly connected to a drive shaft 29 of a low-pressure pump L consisting of a gear pump.

Therefore, when the high pressure pump H operates, this low pressure pump L also operates. And this low pressure pump L
When activated, the strainer 3 provided in the tank 9
The oil in the tank 9 is sucked in from the pipe 3.
1. Discharges pressure oil.

The pressure oil discharged into this pipe 31 is transferred to the first annular passage 18.
is supplied to a passage 32 communicating with the
2 and the check valve t, it joins the discharge passage 2].

Therefore, the passage 32 constitutes a low pressure passage in the circuit shown in FIG. 7.

One end of a joint 34 fitted with a seal member 33 at both ends is attached to the outlet of the discharge passage 21 where oil from the high pressure passage a and the low pressure passage merge (see Figs. 1 and 6). ). In this way, one end of the joint 34 is attached to the outlet of the discharge passage, and the other end of the joint 34 is attached to one end of the communication passage 36 formed in the connection block 35.

Furthermore, one end of a joint 37 similar to the joint 34 is attached to the other end of the communication passage 36, and the other end of this joint 37 is attached to the inlet side of the directional control valve C (see Fig. 1). and the sixth
(see figure).

Now, when the motor M is driven, the drive shafts 11 and 29
rotates, and both pumps H and L operate.

At this time, the pressure oil discharged from the low pressure pump L flows into the directional switching valve C via the pipe 31 → passage 32 → check valve t → discharge passage 21.

The pressure oil that has flowed into the passage 32 also flows into the first annular passage 19, and the pressure oil that has flowed into the first annular passage 19 is sucked into the high-pressure pump H.

The high pressure oil sucked into the high pressure pump H flows into the discharge passage 21 via the discharge valve 18 and the second annular passage 20,
It joins the oil discharged from the low pressure pump L.

In the above configuration, since the help parts for connecting to the high pressure line are integrated into the cylinder bucket I4, the overall size can be made more compact. in this way,
In the high pressure line, piping is not required, and since the valve bases are consolidated as described above, leakage due to piping can be completely prevented.

(Configuration of the present invention) The configuration of the present invention includes a silling block of a high-pressure pump.
A plurality of plunger holes are formed, a discharge valve is connected to each of the plunger holes, and an annular passage communicating with all these discharge valves is formed, and the annular passage is connected to a discharge valve.
The feature is that a connection block is provided between the discharge passage and the directional control valve while communicating with the discharge passage, and the connection block and the discharge passage, and the connection block and the directional control valve are connected by joints. has.

Therefore, the high pressure passage a which is the discharge passage of the high pressure pump H
This eliminates the need for any piping.

(Effects of the present invention) This invention eliminates the need for any piping as described above.
Even non-experts can easily assemble and maintain it.

Further, problems such as leakage from the piping section are also solved.

[Brief explanation of the drawing]

Drawings 1 to 7 show embodiments of this invention.
Figure 2 is a side view of the assembled state, Figure 2 is a cross-sectional view of the high-pressure pump in a connected state with the low-pressure pump, Figure 3 is a side view from the low-pressure pump side, Figure 4 is a cross-sectional view of the high-pressure relief valve, and Figure 5 is a cross-sectional view of the high-pressure relief valve.
6 is a sectional view of an unloading valve, FIG. 6 is a sectional view of an equal pressure passage, FIG. 7 is a circuit diagram, and FIG. 8 is a conventional circuit diagram. H@...high pressure pump, L...O low pressure pump, 14...
Cylinder, 15... Plunger hole, 16ΦΦ・Plunger, 18... Discharge valve, 20... Annular passage, 21...
・Discharge passage, 35 ・φ connection pro-nk, 37 ・・
Coupling, C... Directional switching valve. Representative patent attorney Nobuyuki Shima Kenji Murakami M Figure 1 Figure 2 Figure 1 Figure 5

Claims (1)

[Claims] A plurality of plunger holes are formed in the cylinder block of the high-pressure pump, and a discharge valve is connected to each of the plunger holes, and an annular passage communicating with all these discharge valves is formed. A connection block is provided between the discharge passage and the directional control valve, and the connection block and the discharge passage, and the connection block and the directional control valve are connected by joints. pump.