JPH0442550Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vane pump that is driven at a constant speed by an electric motor, with a suction passage connected to a tank whose liquid level is higher than that of the vane pump.

[Conventional technology]

FIG. 1 is a circuit diagram showing an example of the use of such a vane pump. That is, a vane pump P driven by an electric motor M is installed to supply hydraulic oil from a tank T whose oil level is higher than that of the vane pump P and the cylinder 1 to the cylinder 1 that drives the slide of the press. The electric motor M is a well-known induction motor, which rotates at a substantially constant speed depending on the power supply frequency and the number of poles, and drives the vane pump P at a constant speed. The cylinder 1 has a piston 1A slidably installed in each working chamber 1B, 1 on the head side and the rod side.
A fixed piston 1D is fitted onto the piston 1A to form a working chamber 1E. , 4 to the switching valve 5. Furthermore, a counterbalance valve 6 with a check valve is provided in the passage 4,
A switching valve 7 for switching between fast feed and slow feed is provided between the passage 3 and the working chamber 1B.

Then, when the vane pump P is driven in the state shown in FIG. 1 and the switching valve 5 is switched from the neutral position shown in the figure where the vane pump P is in the unloaded state to the right position, hydraulic oil from the vane pump P is supplied to the working chamber 1E. , the hydraulic oil in the working chamber 1C is returned to the tank T through the counterbalance valve 6, the piston 1A descends in a fast forward state, and hydraulic oil is supplied to the working chamber 1B from the tank T through the pre-fill valve 2. . The tank T applies head pressure to the hydraulic oil so that a large amount of oil can be supplied to accommodate the rapid movement of the piston 1A. During the descent of the piston 1A, when the switching valve 7 is also switched from the normal position shown in the figure, hydraulic oil is supplied from the vane pump P to the working chamber 1B, and at the same time, the pre-fill valve 2 closes and the supply from the tank T is stopped, and the piston 1A is in a slow feed state and processing is performed. After machining is completed, when the switching valve 7 is switched to the normal position shown in the figure and the switching valve 5 is switched to the left position, hydraulic oil is supplied from the vane pump P to the working chamber 1C, and the hydraulic oil in the working chamber 1B is opened to the pre-filled valve. 2, and the hydraulic oil in the working chamber 1E is returned to the tank T through the switching valve 5, respectively.
Piston 1A rises.

[Problem that the invention attempts to solve]

However, in this case, when the vane pump P was started by the electric motor M in an unloaded state with the switching valve 5 at the neutral position shown in the figure, high noise was generated from the vane pump P for a while after starting.

This is due to the following circumstances. In general, the vane pump P has a discharge passage provided inside the vane for distributing the discharged hydraulic oil inside the vane in a vane groove of a rotor that accommodates the vane, as described in Japanese Utility Model Publication No. 51-25765, for example. By connecting, a pressure higher than that of the suction passage is applied to the vane, and in addition to centrifugal force, the vane is moved in the direction of contact with the cam ring.
However, when the vane is stopped, it can be retracted into the vane groove due to its own weight, and most of the vane is separated from the cam ring. There are few vanes that are held in contact and can contribute to the pump action, and the electric motor M quickly reaches a steady constant rotation speed, and because the discharge amount is small, the discharge path pressure caused by flow resistance does not become very large. Therefore, the outward pressing force acting on the vane is small. In addition, the immersed hydraulic oil is given head pressure by the tank T, and since the head pressure acts on the outer end of the vane to move the vane inward, the vane moves outward. is inhibited,
It is not possible to quickly keep all the vanes in contact with the cam ring. Furthermore, this means that when the vanes that are separate from the cam ring move from the suction area to the discharge area of the cam ring as the rotor rotates,
The outer end collides with the discharge cam surface of the cam ring and bounces back, and the sound is further amplified by moving far away from the cam ring and sinking into the vane groove, and this collision of the vanes that are separated from the cam ring generates noise. Noise is generated when a collision situation is not resolved quickly. The reason for this noise generation is that as time passes and the number of vanes that are held in contact with the cam ring and can contribute to the pumping action increases, the discharge amount increases, and the pressure in the discharge passage caused by the flow resistance also increases, causing outward pressure. This is a phenomenon peculiar to startup that eventually resolves itself as the pressure increases, forcing the vanes to come into even more contact with the cam ring. Especially at low temperatures, when the viscosity of the hydraulic oil is high, sliding resistance to the vanes occurs. This was more noticeable in winter when the larvae grew larger.

The present invention aims to reduce the noise generated by the vane pump during startup by increasing the force that presses the vane outward and holding the vane in contact with the cam ring for a short period of time.

[Means for solving problems]

The main body includes a rotor, a cam ring installed on the outer periphery of the rotor, and a vane that is accommodated in a vane groove that is intricately provided in the circumferential direction of the rotor and whose outer end can come into contact with the cam ring. A vane pump connected to the vane pump, which is driven at a constant speed by an electric motor with a suction passage connected to the tank so as to suck working fluid from a tank whose liquid level is higher than that of the vane pump, and which exerts a throttling action on the discharged fluid. A fixed throttle is installed in the discharge passage downstream of the connection point that connects to the vane groove inside the vane. The throttle hole is formed by a concave hole that passes through the disk that is screwed into the screw hole formed by providing a female thread in the screw hole. It opens at the bottom of the tool engaging part for rotational operation and passes through the disc.

[Effect]

According to the configuration of the present invention, when the vane pump is activated by the electric motor and the working fluid flows through the discharge passage, it is subjected to a throttling action by the fixed throttle, and the pressure increases on the upstream side of the fixed throttle. This increased pressure is introduced into the vane groove inside the vane and acts on the vane, creating a large force that pushes the vane outward, even though the head pressure from the tank acts to move the vane inward. , the vane can be held in contact with the cam ring for a short time, reducing noise during startup.

〔Example〕

Hereinafter, one embodiment of the vane pump of the present invention, which is used as shown in FIG. 1, will be described with reference to the drawings.

In Figures 2 to 6, vane pump P
The pump has a main body 10 that houses therein a pump mechanism composed of a rotor, vanes, cam rings, etc., which will be described later. Reference numerals 11 and 12 are end caps of the main body 10. 13
The rotor is spline-coupled to the drive shaft 14, and vanes 16 are slidably accommodated in a plurality of vane grooves 15 provided in the circumferential direction. A cam ring 17 has two discharge cam surfaces 17A and two suction cam surfaces 17B, and is installed on the outer periphery of the rotor 13. 18 and 19 are the cam ring 17 and the rotor 1
This is a side plate provided on both sides of 3. The side plate 18 has two discharge holes 18A and two suction notches 18B, respectively.
It is provided at a position corresponding to the discharge cam surface 17A and the suction cam surface 17B of the cam ring 17, and further so that the inside of the vane 16 in each vane groove 15 is always connected to the discharge hole 18A over the entire rotational area of the rotor 13. , an annular recess 18D and a passage 18C connecting the annular recess 18D to the discharge hole 18A are provided on the rotor 13 side surface. Further, the side plate 19 has a recess 19A at a position corresponding to the discharge hole 18A and a suction notch 19B at a position corresponding to the suction notch 18B, and an annular recess 18D on the rotor 13 side surface.
It has an annular recess 19D corresponding to. 20
represents each discharge passage hole 18A and the main body 10 serving as the downstream end.
It is a guide hole that forms a discharge path 21 together with a screw hole 20A formed by providing a female thread on the inner periphery at the opening end to the main body 10 which is the upstream end of each suction notch 18B, 19B. This is a guide hole that forms a suction passage 23 together with a threaded hole 22A formed by providing a female thread on the inner periphery of the opening end. And suction path 2
3 connects the pipe end of the pipe (not shown) to the screw hole 22A.
or a flange 25 removably attached to the opening surface of the screw hole portion 22A with a bolt 24, and is connected to the tank T.
1 is connected to the switching valve 5 by screwing the pipe end of a pipe (not shown) to a flange 27 that is removably attached to the opening surface of the screw hole 20A with bolts 26. Reference numeral 28 denotes a disk forming a fixed diaphragm R, which has a diaphragm hole 28A passing therethrough that performs a diaphragm function, and is screwed into a screw hole 22A. Note that 28B is the disk 28
This is a tool engaging portion for engaging and rotating a tool for attachment and detachment, and is recessed in the outer end surface of the disk 28. The throttle hole 28A is formed to open at the bottom of the tool engaging portion 28B and pass through the disk 28.

Next, the operation of this embodiment will be explained.

With the switching valve 5 in the neutral state as shown in FIG. 1, the vane pump P is started by the electric motor M. At this time, since each vane 16 can sink into the vane groove 15 by its own weight when stopped, only a part of the vanes 16 are in contact with the cam ring 17, and all vanes 16 contribute to the pump action immediately after starting. However, a pumping action is obtained by some of the vanes 16, and the hydraulic oil flows through the discharge passage 21, and the throttle hole 28
A causes the pressure to increase upstream of the throttle hole 28A. Vane 16 in each vane groove 15
Since the inner side is connected to the discharge hole 18A of the side plate 18 through the annular recess 18D and the passage 18C, this rising pressure is introduced and acts on each vane 16 and presses it outward with centrifugal force. Although the head pressure from the tank T acts to move the vanes 16 inward, each vane 16 is pressed outward with a large force and is quickly held in contact with the cam ring 17. That is, due to the effect of the rising pressure introduced through the annular recess 18D, the number of vanes 16 in contact with the cam ring 17, which can contribute to the pumping action, increases, and the discharge amount increases, and accordingly, the amount of discharge due to the throttle hole 28A increases. As the pressure rise increases, more and more vanes 16 come into contact with the cam ring 17, so that a state in which all of the vanes 16 are held in contact with the cam ring 17 can be achieved in a short period of time. Therefore, the vane 16 that is separated from the cam ring 17 is prevented from continuously colliding with the discharge cam surface 17A of the cam ring 17 over a long period of time as the rotor 13 rotates, and the noise during startup is significantly reduced. Ru.

The throttle hole 28A exerts a throttle action even after the vane pump P is in a steady driving state in which the entire vane 16 is held in contact with the cam ring 17 and contributes to the pump action, so an extreme throttle action causes a large power loss. This is not desirable, and it is necessary to determine the diameter of the aperture hole 28A after testing to determine the diameter of the aperture hole 28A that can sufficiently prevent noise. A sufficient effect was obtained as long as the pore diameter was large enough to generate a pressure difference of 2 kg/cm ² . And the aperture hole 28A
Regarding the allowable differential pressure in advance,
If you understand the relationship between the flow rate and the hole diameter, you can easily obtain the throttle hole 28A with an appropriate hole diameter even when selecting electric motors M with different rotational speeds in response to various discharge volume requirements. Aperture hole 28A
The disk 28, which has an appropriately defined hole diameter, is inserted into the tool engaging portion 28B and then engaged with the tool, and the tool is rotated to screw into the screw hole 22A, and no adjustment work is required, making handling easy. In this screwing operation, since the screw hole 22A is located at the open end of the guide hole 20 that opens to the outer surface of the main body 10, the disk 28 can be screwed into the screw hole 22A from outside the main body 10. Easy to work with. The disk 28 is opened at the bottom of the tool engaging portion 28B that engages a tool for rotational operation, and has an aperture hole 28A formed therethrough.
Even if the shape is small, space for tool engagement can be easily secured. Further, the fixed throttle R formed by the disk 28 is built into the vane pump P, and can be used without changing the existing hydraulic circuit.

In addition, in this embodiment, the inside of each vane groove 15 inside the vane 16 is always connected to the discharge path 2 by the annular recess 18D and the passage 18C in the entire area on the rotational circumference of the rotor 13.
1, the connection between the vane groove inside the vane and the discharge passage is made only in the area corresponding to the discharge cam surface of the cam ring, as shown in Japanese Utility Model Publication No. 16407/1983. It can also be applied to operations that are limited to a limited area on the rotational circumference.

[Effect of idea]

In this way, the present invention includes a rotor in the main body, a cam ring installed on the outer periphery of the rotor, and a vane that is accommodated in a vane groove formed in a complicated circumferential direction on the rotor and whose outer end can come into contact with the cam ring. A vane pump that is connected to a discharge passage inside the vane.The suction passage is connected to the tank so that the hydraulic fluid is sucked from the tank whose liquid level is higher than that of the vane pump, and the suction passage is driven at a constant speed by an electric motor. A fixed orifice that exerts a throttling effect on the liquid is installed in the discharge passage downstream of the connection point that connects to the vane groove inside the vane. It is formed by a throttle hole passing through a disc that is screwed into a screw hole formed by providing a female thread on the inner periphery at the open end of the disc. It opens at the bottom of the tool engagement part for rotating operation, which is recessed in the outer end surface of the plate, and passes through the disk, so during startup, the hydraulic fluid flowing through the discharge path is throttled by a fixed throttle. The increased pressure caused by the throttling action is introduced into the vane groove inside the vane, and the vane is pushed outward with a large force, so the vane is held in contact with the cam ring in a short time, and when the vane pump is started. noise is reduced. In addition, it is easy to handle and requires no adjustment work, simply by screwing a disk with a throttle hole with an appropriate degree of throttle in accordance with the selected motor rotation speed into the threaded hole of the discharge passage. Since the bottom of the tool engagement part recessed on the outer end surface is opened and a throttle hole is formed through it, it is possible to easily secure the space for engaging the tool for rotation operation even if the size is small. can. The screw hole part is provided at the opening end of the discharge passage to the outside of the main body, so the screwing operation of the disk can be easily done from outside the main body.Furthermore, it can be fixed to the vane pump itself. Since it has a built-in throttle, it can be used without changing the existing hydraulic circuit.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an example of the use of a vane pump, Figs. 2 to 6 show an embodiment of the present invention, and Figs.
3 is a partial sectional view along the line - of FIG. 6, FIG. 4 is a front view of the disk 28, FIG. 5 is a front view of the side plate 18, and FIG. 6 is a front view of the side plate 18. FIG. 2 is an enlarged partial cross-sectional view taken along line - in FIG. 2; 13... Rotor, 15... Vane groove, 16...
Vane, 17...cam ring, 21...discharge path,
23... Suction path, M... Electric motor, P... Vane pump, R... Fixed throttle, T... Tank.

Claims (1)

[Scope of utility model registration request] The main body includes a rotor, a cam ring installed on the outer periphery of the rotor, and a vane that is accommodated in a vane groove that is intricately provided in the circumferential direction of the rotor and whose outer end can come into contact with the cam ring. A vane pump connected to the vane pump, which is driven at a constant speed by an electric motor with a suction passage connected to the tank so as to suck working fluid from a tank whose liquid level is higher than that of the vane pump, and which exerts a throttling action on the discharged fluid. A fixed throttle is built into the discharge path, located downstream from the connection point that connects to the inside of the vane and inside the vane. It is formed by an aperture hole that passes through a disk that is screwed into a screw hole formed by providing a female thread, and this aperture hole is recessed in the outer end surface of the disk that is screwed into the screw hole. A vane pump consisting of an opening at the bottom of a tool engaging part for rotational operation and passing through a disc.