JPS6332932Y2 - - Google Patents

Description

[Detailed description of the invention] This invention combines a low-pressure pump such as a gear pump and a high-pressure pump in which a plunger inserted into a cylinder is in sliding contact with a swash plate cam so as to perform a pumping operation, using a single driving source such as an engine. The present invention relates to means for following a swash plate cam of a plunger constituting the above-mentioned high-pressure pump unit, particularly for a hydraulic pump unit of a type operated by a high-pressure pump unit.

By the way, conventionally, the means for following the plunger to the swash plate cam has been a means of using a spring to press the plunger against the swash plate cam, but since the swash plate cam rotates at a high speed due to the drive source, If the spring is not made strong, the plunger will not be able to properly follow the swash plate cam, and if the spring is made too strong, the problem will be that too much load will be placed on the drive source, causing a loss of output.

Therefore, this idea attempts to press the plunger against the swash plate cam by using the pump unit's own hydraulic oil without using a spring, but in order to do so, it is difficult to maintain constant hydraulic pressure. The problem is how to make the plunger work.

Therefore, the present invention has been devised to the hydraulic circuit, making it possible to effectively achieve the follow-up sliding contact of the plunger with the swash plate cam using only hydraulic oil, and also eliminate the problem of output loss of the drive source. The purpose is to

First, details of the embodiment will be described with reference to the drawings. 1st
In the figure, reference numeral 1 denotes an oil tank, and into this oil tank 1 is inserted a base 2 fixed to the tank and having a hydraulic pressure generating function section to be described later.

A rotating shaft 3 driven by an engine or motor (not shown) is inserted into the base 2, and a low-pressure pump A consisting of a gear pump and a gear pump are driven together by the rotation of the shaft. High pressure pump B is connected. The high-pressure pump B has multiple pairs of a swash plate cam 4 provided on a rotating shaft 3, a suction plunger 6 inserted into a suction side cylinder 5 provided on a base body 2, and a discharge plunger 8 inserted into a discharge side cylinder 7. The plunger is slidably connected to the plunger. Note that the low pressure pump A and high pressure pump B have well-known configurations.

The suction side of the low-pressure pump A is opened to communicate with the oil tank 1 through the element 9, and the discharge side of the low-pressure pump A is branched into communication with a low-pressure output passage 10 and a high-pressure generation guide passage 11, so that high pressure can be generated. The guide passage 11 communicates with the suction side cylinder 5 via an annular inflow groove 12 provided in the base body and a suction valve 13.

Further, the discharge side cylinder 7 communicates with an annular discharge groove 14 provided concentrically outside the inflow groove 12 via a discharge valve 15, and both grooves 12 and 14 communicate with each other via a communication groove 15'. , and the discharge groove 14 is communicated with a high pressure output passage 16 provided in the base body.
An appropriate load such as a tool is connected to the outlet end of this high pressure output passage 16.

As shown in the side sectional view of FIG. 2, the low pressure output passage 10 joins the high pressure output passage 16 in the middle through a first valve 17 that closes when the internal pressure of the high pressure output passage 16 increases, which will be described later. It is communicated.

The low pressure output passage 10 has one end connected to the oil tank 1 and the other end of the relief passage 18 connected to the second valve 19.
The second valve 19 is normally biased to close so as to cut off the communication between the relief passage 18 and the low pressure output passage 10, and is opened by an increase in the internal pressure of the low pressure output passage 10. It's summery. Also, a valve support member 20 faces the second valve 19, and this valve support member 20 is inserted into a cylinder 21 whose one end is communicated with the high pressure output passage 16. Move the second valve 19
The above-mentioned open state is maintained.

Therefore, the essential structure of the present invention is that the valve is located within the relief passage 18 and behind the second valve 19, and is opened so that the hydraulic pressure generated in the passage 18 escapes to the oil tank while applying resistance. A third valve 22 is provided.

Therefore, the operation of the above-mentioned unit will be described by taking as an example the operation of a crimping tool for electric wires or the like.

The low-pressure pump A and high-pressure pump B are driven together by the drive of the rotating shaft 3, and oil from the low-pressure pump A is branched and supplied to a low-pressure output passage 10 and a high-pressure generation guide passage 11 connected to the discharge side of the low-pressure pump A, respectively. However, since the amount of oil in the low pressure output passage 10 is large, most of the oil is
As shown in Figure A, the first
The valve 17 is pushed open to join the high-pressure output passage 16 and flow into the cylinder of a tool (not shown) connected to the high-pressure output passage 16, and the crimping ram in the cylinder is moved rapidly to the position where crimping of the electric wire starts. When the crimping ram comes into contact with the electric wire and receives resistance, the internal pressure of the high-pressure output passage 16 increases, and as a result, the first valve 17 opens as shown in FIG. 3B.
is closed, and as the first valve 17 is closed, internal pressure is also generated in the low pressure output passage 10, which pushes the second valve 19 open, and at the same time, due to the increase in the internal pressure of the high pressure output passage 16. The valve support member 20 moves to the left in the figure to face the opened second valve 19.
The second valve 19 is kept in an open state by contacting the second valve 19 as shown in FIG.
The hydraulic pressure escapes into the passage 18, but there is a third valve 22 in the passage 18.
Therefore, hydraulic pressure is applied to this relief passage 18 as well, and the third valve 22 opens at the set pressure as shown in FIG. The pressure in the hydraulic circuit is kept constant without fluctuations by releasing it into the tank 1. This means that a constant hydraulic pressure is always applied to the plungers, giving the plungers 6 and 8 a stable follow-up force to the swash plate cam 4.

The wire is crimped with the tool in the state shown in Figure 3 D above, and after crimping is completed, the hydraulic pressure inside the tool is released by operating a relief valve (not shown) in the tool or unit, and the crimping ram is closed with a spring or the like. Of course, he will be reinstated.

By the way, as another means of biasing the plunger to follow the swash plate cam without using a spring, for example, as shown in FIG.
2' could simply be used to stabilize the oil pressure in the circuit, but with this configuration, heat is generated in the above-mentioned choke part, and to make matters worse, this heat generation causes bubbles in the oil. It has been found that for this reason, the oil pressure in the circuit inevitably fluctuates and becomes unstable, making it impossible to obtain a stable pressing force of the plungers 6, 8 against the swash plate cam 4.

Therefore, in this invention, as described above, the third valve 22 is provided in the rear relief passage 18 of the second valve 19, and this valve 22 stores hydraulic pressure in the relief passage 18 while simultaneously resisting the hydraulic pressure. As the heat is generated at the third valve 22 position, the oil in this area is directly returned to the oil tank, so the heat does not dissipate. Nothing is transmitted to the oil in the circuit, so a stable hydraulic pressure is always maintained in the circuit, and this stable hydraulic pressure pushes the plunger, allowing the oil to follow the plunger to the swash plate cam. This makes it possible to obtain a large amount of force, and it also eliminates the need to place a high load on the drive source, allowing for light pumping function, which is a great feature.

[Brief explanation of drawings]

Figure 1 is a partially cutaway front view, Figure 2 is A to A
A side sectional view of the line part, FIGS. 3A to 3D are explanatory views showing the hydraulic operation stroke, and FIG. 4 is another explanatory view.

Claims (1)

[Scope of utility model registration request] A pump unit that commonly operates a low-pressure pump A such as a gear pump and a high-pressure pump B formed by sliding plungers 6 and 8 inserted into a cylinder and following the swash plate cam 4 using one drive source, and the low-pressure pump A described above A low pressure output passage 10 and a high pressure generation guide passage 11 are commonly branched and communicated on the discharge side of the
The high-pressure generation guide passage 11 is communicated with the cylinder of the high-pressure pump B so that only the oil flowing into the cylinder biases the plungers 6 and 8 to follow the swash plate cam 4, while the low-pressure output passage 10
is connected to the high pressure output passage 16 for load operation, which is connected to the discharge side of the high pressure pump B, through a first valve 17 that closes when the internal pressure of the passage increases,
In addition, the other end of the relief passage 18, which has one end communicating with an oil tank or the like, is normally closed and biased to cut off the communication between the relief passage 18 and the low pressure output passage 10, and the low pressure Output passage 1
The second valve 1 opens when the internal pressure increases by 0 and maintains this open state by a valve support member 20 that moves as the internal pressure increases in the high-pressure output passage 16.
9, and a third valve 22 is provided in the rear relief passage 18 portion of the second valve 19, which acts to release the hydraulic pressure generated in the passage to an oil tank or the like while applying resistance. A hydraulic pump unit characterized by: