JPS5960088A - Variable delivery volume vane pump - Google Patents

Abstract

PURPOSE:To prevent generation of surging by a method wherein the excess pressure oil in the subpressure chamber of a sub piston, whose amount is corresponding to the delay of the response of a variable mechanism which generates a surge pressure, is escaped into a tank through a surge absorbing valve arranged in relation with the pump. CONSTITUTION:For instance, in case a cylinder is stopped suddenly at the end of the stroke thereof, the surge pressure is generated in the pump and the control pressure of the pressure chamber 23 of a main piston 4 shows a similar peak pressure. When the surge pressure of the control pressure has become larger than a set pressure for a spring 108, the poppet 107 of the surge absorbing valve A moves to the right as shown in the diagram and the control pressure of the sub pressure chamber 22 escapes to a tank port T. According to this operation, the surge pressure, exceeding a pump pressure corresponding to the set pressure, is removed. Accordingly, the best surge absorbing capacity may be maintained at all times in spite of the set pressure of the pump.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in pressure compensated variable displacement vane pumps.

Such a variable discharge volume vane pump operates a pump discharge variable device when the self-discharge pressure rises to a preset pressure level so that the pump discharge volume is large at low pressure and small at high pressure, that is, at ted head pressure. to reduce the pump discharge amount. r, there are sea urchins.

The hydraulic circuit 7 using a variable discharge vane pump with this structure has the ability to absorb relief valve surge pressure, compared to a hydraulic circuit that combines a constant discharge volume valve and IJ to IJ 7 and z" valves. For example, when the actuator suddenly stops or the valve suddenly closes inside the variable discharge vane pump,
Surge pressure is likely to occur when The surge pressure that occurs is usually about 15 to 3 times the set pressure of the variable displacement vane pump, ff1J, and the ted bed pressure.For example, the dead head pressure is set to a maximum of 70'PI'/cl+. At times, the surge pressure can reach as much as 200 J'/A, and as a result, the sliding surfaces and other parts of the pump are subjected to excessive loads, rapidly reducing the life of the pump. Surge pressures in associated hydraulic circuits can shorten the lifespan of equipment such as valves and actuators. Moreover, this surge pressure caused excessive strain in the constituent members of the pump and equipment, resulting in a decrease in the performance of the pump and equipment.

In order to absorb the surge pressure of the variable displacement vane pump, for example, IJ I7 is added to the variable displacement vane pump.
- It has been proposed to install a valve to relieve part of the pump discharge pressure. In addition, for example, the auxiliary pressure chamber i 1 J IJ- is connected directly to the auxiliary pressure chamber i 1J IJ- valve of the auxiliary piston, which is disclosed in Japanese Patent Application No. 103624/1989, which is being filed and unpublished by the applicant. In order to prevent the generation of surge pressure, methods have been proposed to absorb the surge pressure of the pump. However, even in the case of stiffness n, when changing the pump setting pressure, the valley IJ IJ-7
It is also necessary to change the set pressure of the valve; otherwise, when the set pressure of the pump is lowered, a surge pressure will occur, and conversely, when the set pressure is set higher, part of the pump discharge volume will escape from the relief valve to the tank. This is said to be the cause of a loss in displacement and horsepower, as well as an increase in oil temperature. For this reason, it is troublesome to handle, and the relief valve's null ring must be large, which poses problems such as the small valve being difficult to open. Furthermore, as a method for absorbing surge pressure, it is also proposed to install an accumulator with f' that can communicate with the discharge oil of a variable displacement vane pump, or to install a combination of an accumulator with σ and a relief valve. I'm here. However, the accumulator is not only expensive, but also has drawbacks such as the capacity of the accumulator must be changed in accordance with the flow rate and pressure of the hydraulic circuit, and it is difficult to handle such adjustments.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a variable displacement vane pump that eliminates surge pressure and does not require adjustment even if the set pressure or deadhead pressure changes.

Another object of the present invention is to absorb excess pressure oil in the auxiliary pressure chamber of the auxiliary piston in an amount corresponding to the response delay n of the variable mechanism that generates the full surge pressure in a pressure-compensated variable discharge vane pump. An object of the present invention is to provide a variable discharge amount pump which discharges water to a tank via a valve and prevents the generation of surge pressure.

The above-mentioned and other objects and advantages of the present invention include a main piston that presses a link in a direction that reduces the amount of eccentricity between the rotor and ring of a vane pump, and a main piston that presses a link in a direction that reduces the amount of eccentricity between the rotor and ring of a vane pump, and a pressure chamber that pumps discharged oil from the pump into a pressure chamber of the main piston. an oil passage that guides the compen safe by valve, a second oil passage that guides the pressure oil in the pressure chamber through the passage, and an auxiliary piston that is located on the opposite side of the main piston and presses in a direction to increase the amount of eccentricity. a third oil passage for guiding discharge pressure oil of the pump to a sub-pressure chamber of a sub-piston; a small piston to which the pressure oil of the pressure chamber is guided; and a valve device opened and closed by the small piston. , a bypass oil passage for guiding the control pressure oil in the auxiliary pressure chamber to the valve device, and a bypass oil passage for guiding the control pressure oil from the valve device to the tank when the valve device “η” is opened. This can be achieved by a variable displacement vane pump characterized by a surge absorbing valve all associated with the arrangement.

The pressure of the pressure oil in the pressure chamber is throttled by a pressure compensator.
By properly selecting the orifice, even if the set pressure of the pump is changed, fff7 Even if the set pressure (dead head pressure) of the same pump increases or decreases, it will not work between pumps with different maximum pressures. Even if the set pressure differs, the power can be maintained within a relatively narrow range of, for example, 20 KyfAol to 3°Sj/d.For this reason, even if the set pressure of the pump, that is, the deadhead pressure, changes, There is no need to change the pressure setting of the surge absorption valve, and therefore surge pressure can be efficiently removed without the need for additional adjustments.

Although the surge pressure absorption valve may be placed inside the pump and outside the pump, it is preferable to connect the oil passage and the bypass oil passage in order to simplify the piping and downsize the entire device. Good too. When the pump capacity is large and it is necessary to release a large amount of excess pump pressure oil in order to completely prevent the generation of noon pressure, it is preferable to operate the pump in the bypass oil passage behind the valve device. A safety relief valve may be activated.

In order to make the surge absorption performance effective, the pressure oil in the pressure chamber is guided to the small piston through a throttle valve that throttles only in the backward direction. , the amount of pump pressure oil released into the tank may be increased by slightly delaying the return sound pattern 9 valve of the valve device.

The valve device is preferably a poppet valve, but may also be a spool valve. More preferably, the valve device can be provided with a stopper that limits the degree of opening.

The variable displacement vane pump of the present invention is used in a hydraulic circuit.
For example, suppose that the cylinder suddenly reaches the end of its stroke in actual use. Then, the variable mechanism of the variable pump comes into play, and the discharge amount of the pump is reduced to near zero, that is, the ted head discharge volume is reduced. In the conventional known variable discharge amount vane pump, a surge pressure (Ps) is generated in the pump pressure (CP) as shown by the solid line in FIG. 1 due to the response delay n of the variable mechanism. After repeating some vibrational waves, the ted head pressure C
PDH). At this time, the control pressure of the main piston (
PP) also generates a serve pressure (ki P8)2 which is almost the same as the pump pressure (), and then the pump's ted head pressure (
The dead head pressure CPPDH) is the control pressure corresponding to the deadhead pressure CPPDH). In the present invention, this control pressure (PPi) is applied to the small piston to open the valve device and release a part of the control pressure oil in the sub-pressure chamber of the sub-piston to the entire tank, which causes the surge pressure to be generated in the sub-pressure chamber. This prevents abnormal pressure from occurring, allows ring transfer 1 to occur smoothly, and completely eliminates surge pressure.To be more precise, the set pressure at which the surge absorption valve operates is equal to the dead pressure of the control pressure (Pp). Pressure CP slightly higher than head pressure (PpDH,)
PR) is set to n, which corresponds to the pump pressure HPR corresponding to n. and this FRI at pump pressure (P)
At the control pressure (P), the surge pressure exceeding PPRk is removed.

In addition, the responsiveness itself is improved to prevent abnormal pressure from occurring in the sub-pressure chamber of the sub-piston.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Exemplary preferred embodiments of the invention will be described in detail with reference to the drawings. The part of the variable discharge vane pump shown in FIG. 2 excluding the surge absorption valve (A) is the variable discharge vane pump disclosed in Japanese Patent Application Laid-Open No. 57-5585, and this part itself is not included in this book. Since it does not constitute an invention, details (( will not be explained.

Figure 2 shows the liquid field type O used in machine tools and industrial equipment.
The J-variable displacement vane pump is shown in a cross-sectional view taken along a perpendicular plane passing through the valley axes of the sub-piston and the main piston. Third
The diagram is schematically shown in FIG. 2 (hydraulic circuit diagram).

Inside the pump (1) are a plurality of vanes (9) that can freely move in and out in the radial direction, a fully inserted rotor (8), and a rotor (8).
) and side plates (not shown) are provided on both sides of the rotor (8) and the ring (7).The sub piston (5) has one end in contact with the ring (7). contact,
The other end of the spring (10, J) is biased to fully press the ring (7) towards the center (01) of the rotor (8)
ing. Furthermore, the pump discharge pressure is applied to the sub-pressure chamber (c) which acts on the sub-piston (5) in the oil passage tA (pump discharge oil chamber (
(includes an oil passage (not shown) that communicates with one of the oil passages) through the throttle valve body (g), and acts on the surface (5') that receives the pump discharge aEk of the sub-piston (5), thereby causing the sub-piston (5) to
The ring (7) is biased to be pressed in the right direction as viewed in FIGS. 2 and 3. A secondary screw on the opposite side of the secondary piston (5) with respect to the rotor (s) i center (01)!
- A main piston (4) is provided almost coaxially with the piston (5). The main piston (4) is in contact with the Kelling (7) K at one end, and the other end (the main piston (4) is in contact with a discharge rate adjustment screw (13).The discharge rate adjustment screw (13) is linked via the main piston (4). (7) The maximum amount of eccentricity is limited.

The main piston (4) is fully operated in the pressure chamber (c) through which the pump discharge oil passes through the oil passage C]) (including an oil passage (not shown) that communicates with the pump discharge oil chamber OQ) and passes through the pressure compensator (3).
) through 4 forces), and the surface receiving the pump discharge pressure (
4'] to urge the main piston (4) to the left in FIGS. 2 and 3 so as to suppress the ring (7). The pressure compensator (3) controls the hydraulic pressure acting on the main piston (4), and is connected to the Suf-Link (2% 1c spool (6) biased in the closing direction by 1υ) and the pressure adjustment screw ( lΦ and Bo! (1ηIA
C'19), and when the pump discharge pressure is lower than the pressure set by pressure adjustment, the pressure receiving surface of the spool (6) communicates with the oil passage Q1) (17) 'e boat θ Closed against the mark.

When the pump discharge pressure exceeds the set pressure, the pressure oil flows from Bo+4η to the boat Q barrel into the pressure chamber (c). (19) is a drain boat that communicates with the tank or pump drain section.

In this embodiment, there is a second oil passage (c) located approximately in the center of the main piston (4), which has one end open on the pressure chamber and thus the surface (41), and the other end communicates with the tank (pump drain part) via the aperture α2. The state shown in Figures 2 and 3 is also the position where the pump is stopped, and the ring (7) is pushed to the right by the spring (10) via the sub-piston (5). 9. Center of ring (7) and center of ring (8) (
e) is eccentric by the maximum eccentricity set by the discharge adjustment screw α1. When the reed rotor (8) rotates counterclockwise in the direction of the arrow C, the pump sucks oil from the lower suction chamber 0 through a boat (not shown), and increases the discharge pressure from the upper discharge chamber 0Q. ] The pump discharge oil is discharged through a holer (not shown). This pump discharge pressure) is passed through the third oil passage throttle valve body □□□ to the sub piston and then to the pressure convencator (3).
It acts on the pressure receiving surface of the spool (6).

When the hydraulic pressure due to the pump discharge pressure (P) acting on this pressure-receiving surface is smaller than the spring force set by the pressure adjusting screw 0, the ring (7) moves into the sub-pressure chamber (c). The sub-piston (5) on which the combined force of the hydraulic pressure and the spring force of spring 00 acts pushes the pump toward the right, and the pump discharges according to the maximum eccentricity set with the discharge adjustment screw al. Dispense amount.

When the pump discharge pressure) becomes high and the hydraulic pressure acting on the pressure receiving surface of the spool (6) becomes stronger than the spring force of the spring aυ, the spool (6) is moved to the right.

Then, the pump discharge oil passes through the boat αηα mark from the oil passage (c) and enters the pressure chamber (damage) of the main piston (4). A portion of this pressure oil passes through the second oil passage (goods) and escapes from the outlet (c) to the pump drain section (and by extension, the tank) (not shown).
However, the pressure oil throttled by the throttle α2 increases the pressure in the pressure chamber and acts on the surface (41). As the pump discharge I″E (″) increases, the spool (6) moves to the right. increases, and the control pressure (Pp) of the pressure chamber (c) increases (
(The hydraulic pressure due to the control pressure (Pp) acting on the surface (41) of the main piston (4) is applied to the surface (51) of the secondary piston (5).
The ring (7) overcomes the resultant force of the hydraulic pressure acting on the spring (10) and moves completely to the left.As a result, the discharge amount of the pump decreases, and the pump discharge pressure (P) is adjusted in advance by adjusting the pressure adjustment screw ( When the pressure set in step 14 (i.e., dead head pressure (PD) I) rises, it becomes a dead head state where pressure oil is no longer discharged, and the center of the ring (7) (02) is the center of the rotor (8) (O19). is almost equal to

Next, when the pump discharge pressure ('') decreases below the set pressure CPDH), the spool (6) moves to the left and the amount of pressure oil flowing into the pressure chamber (c) decreases, resulting in The pressure in (c) decreases, and the ring (7) is not moved to the right by the resultant force KJ: of the hydraulic pressure acting on the sub-piston (5) and the spring θ0.As a result, the pump discharge The amount increases and the pump returns to the state shown in FIGS. 2 and 3.

(A) shown in FIGS. 2 and 3 shows the entire surge absorption valve according to the present invention. The surge absorption valve (A) consists of a housing (101) that is integrated with the pressure compensator (3) (they may be separate units for ease of processing), and a hollow hole t' drilled in the housing (101). a small piston (102) slidably fitted into the small piston (102);
) of the main piston (4) in the oil chamber (110) of the main piston (4).
an oil passage (103) that guides control pressure oil, and a small piston (10
2) and a valve device (B) connected by a small diameter connecting rod (105) and having an f'-shaped boppest (107).

The valve device CB) is suppressed by a spring (]08) so as to close the pump discharge pressure boat (P) against the pump discharge pressure boat (P), and the strength of this tin link is determined by the screw ( ], 1.1). In the embodiment, a stroke bar (109) is provided to limit the opening degree of the boppet 1 (107), but this presses the small piston (102) due to surge pressure compared to the spring force of the spring (108). When the force is extremely large, it is necessary to adjust the maximum opening degree in order to prevent problems such as inoperability due to excessive force (107), and to take into account the magnitude of the surge pressure in the hydraulic circuit. There are a number of ways to do this. The discharge oil hoard (P) has an auxiliary piston (
5) The control pressure oil in the auxiliary pressure chamber @ is guided through a bypass oil passage (104) including a pump internal passage (not shown).
, l-(T) is a drain oil passage (10) including a pump internal passage (not shown);
I'm here.

Control pressure (PP) of oil chamber (a) of main piston (4) n
In order to guide the pump discharge oil through the pressure compensator (3) and to appropriately select it according to the total pump rated discharge pressure and flow rate of the throttle 90! ll, usually 20'yf/c
d-a.

'yfArl' can be set within an extremely narrow range. This control pressure (PP) can be maintained approximately within the above pressure range even if the set pressure, that is, the ted head pressure changes, or even if the set pressures differ between pumps with different maximum pressures. Bobetsu) (107)'
The strength of the pushing spring (108) is set to the pressure at dead head (PPD) as explained earlier in Figure 1. becomes (h).

When the load on the hydraulic circuit to the pump, that is, the load applied by starting/stopping the actuator or opening/closing the valve, increases gradually, the pump pressure (i-j) is as shown in Figure 1. Dead head pressure (PD) I) rises statically in the trench without generating surge pressure (Ps)-i. At this time, the control pressure (PP) is also the pressure CPPDH)'! rises statically. At this time, the hydraulic pressure acting on the small piston (302) of the surge absorption valve (A) is also caused by the spring (108).
The set pressure CPPR) k cannot be exceeded, so the second
As shown in FIG. 3, the poppet (107) is closed and the valve system (in the valve system) is in an inoperative state.

On the other hand, when the pump load is, for example, when the cylinder suddenly strokes and stops, or when the cell is completely suddenly closed, surge pressure (PS) is generated in the hydraulic circuit and eventually inside the pump. occurs. The control pressure (PP) then exhibits a similar peak pressure as explained in FIG. When the surge pressure of this control pressure (Pp) increases, the set pressure CPPR)
(107) is moved to the right in Figures 2 and 3.
, discharge pressure bow 1- (to) to tank bow 1- (T)
The control pressure oil in the auxiliary pressure chamber (c) escapes towards. Due to this, the surge pressure (PS) becomes the above pressure CP as seen in Figure 1.
Pressures exceeding the pump pressure (PR) corresponding to PR) are removed. When the control pressure (PP) becomes smaller than the set pressure CPPR) of the tin link (1os), the
107) is pushed by the spring (108) and is not closed, so that the control pressure oil in the auxiliary pressure chamber (C) does not escape. Since this control pressure (PI') is within an almost narrow pressure range as mentioned above, compared to the case where a conventional IJ valve is installed and the pump discharge pressure is pumped, the pump set pressure part or dead head pressure is There is no need to change the set pressure (PpR) every time the pump pressure changes, and the best surge absorption capacity can always be maintained regardless of the pump set pressure. In the above, when surge pressure is generated, this surge pressure is also transmitted to the auxiliary pressure chamber (C) via the throttle valve body (3), causing the ring (7) to move in the direction of reducing the discharge amount to a deadhead state. Fully actuate the sub piston (5) in the blocking direction. At the same time, the main piston (4)'s pressure chamber (a) (') is also transmitted with surge pressure, and the main piston (4) presses the ring (7) toward the sub-piston, resulting in the sub-pressure of the sub-piston (5). Chamber 2 is exposed to a pressure even higher than the surge pressure (Ps) when there is no surge absorption valve (A), so the secondary piston (5) further pushes the ring (7) to the right, resulting in even more surge pressure. However, the present invention prevents such a situation.

In this way, the variable discharge amount vane pump used in the present invention can effectively remove surge pressure at all times without the need for troublesome adjustments once the spring (108) is set. The service life can be extended, and furthermore, it is possible to prevent performance deterioration and equipment damage under mechanical precision R caused by excessive pressure load VC, J: distortion.

In the preferred embodiment described above, the pump discharge oil is transferred to the secondary piston (
5) Throttle valve body 03 is installed in the third oil passage leading to the auxiliary pressure chamber (22).
0) When the surge absorption valve (A) opens and the control pressure oil in the auxiliary pressure chamber (A) escapes to the tank,
1. Let the supply of 1% pump discharge oil replenish from the pump take some time.1. J:, p This is to effectively lower the pressure in the sub-pressure chamber 32, and when the surge pressure is relatively small, this step may be omitted.

Fig. 4 shows a surge absorption valve different from Fig. 2, and Fig. 5 shows a hydraulic circuit diagram when the surge absorption valve of Fig. 4 is applied to a variable discharge amount vane pump as shown in Fig. 2. It is a schematic diagram. Components equivalent to those in FIGS. 2 and 3 are designated by the same reference numerals. In the embodiment shown in FIG. 4, the pump capacity is increased,
If it is necessary to increase the amount of control pressure oil in the auxiliary pressure chamber (A), the pump internal dimension is communicated with the bypass oil passage (104) via a relief valve (112) in the hydraulic circuit. The control pressure oil of the auxiliary pressure chamber (A) is guided to the relief inlet (1, 13), and the discharge oil boat of the surge absorption valve (A) is communicated with the relief oil chamber (99) through the oil passage (114). n
ing. Then, when the small piston (1, 02) is operated and the n1 poppet (107) is opened, the pressure in the oil chamber (1, 19) decreases, the relief valve body (11, 5) opens, and the bypass oil passage is opened. A large amount of control pressure oil (104) is supplied to the drain oil path (104).
17).

Here's another example! In Figure 6, the valve device is a spool valve with a spool (120) connected by a small piston (101) and a small diameter rond (105'), which is connected to the spool (120) by a coil spring (1os').
) The discharge oil boat is closed to the tank boat +- (T), and the movement of the spool (120) is restricted by the nutopper (109'). This operation is almost the same as that of the poppet valve previously described with reference to FIGS. 2 and 3, and the explanation thereof will be omitted. In Figure 6, in order to make the surge absorption performance even more effective, the pressure chamber of the main piston (4) is
A throttle valve (12) is installed in the oil passage (1,03) that leads the pressure oil to the oil chamber (110) of the small piston (101) in the backward direction.
1,, ), the surge pressure decreases and the valve device, that is, the spool (120) in FIG. 6, springs off the coil (108'
) return sound valve (12) of the valve device closed by
), which increases the amount of relief of control pressure oil into the tank from the auxiliary pressure chamber.

In the embodiment, the surge absorption valve (8) is arranged integrally with the pump, but it may be arranged outside the bong and connected to the pump by piping.

[Brief explanation of the drawings] if 1 Figure shows the pressure and time fb of the variable discharge vane pump.
Figure 2 shows a cross-sectional view of a preferred embodiment of the invention, Figure 3 shows a schematic diagram of 1 in a hydraulic circuit diagram, 4 and 5 show another preferred embodiment of the present invention, FIG. 4 shows a surge absorption valve different from that in FIG. 2, and FIG. 5 shows a schematic diagram of a device using this surge absorption valve. The hydraulic circuit diagram is shown, and FIG.
FIG. 6 shows a schematic hydraulic circuit diagram of another preferred embodiment; A...Surge absorption valve B...Valve device 3...Pressure compensator 4...Main piston 5...Sub-piston 7...1 Nong 12... Throttle
20... Koma532
Mountain path 21...Oil passage 22...Sub-piston chamber 23...Pressure chamber 24...Second oil passage 30
... Throttle 9 valve body 102 ... Small piston 104.
...Bayhas l'[4] Route 106...Drain oil route 1
07...Poppet 108...Spring 108'
... Coil is h 1o9.1o9' ... Nutoppa 112 ... Relief valve 120 ... 2 pools] 21 ... Throttle valve agent Jun Kawachi Fake age □ C rf″1 rh

Claims (7)

[Claims] (1) A main piston that presses the link in a direction that reduces the amount of eccentricity between the rotor and the ring of the vane pump, an oil passage that guides the pump's discharge pressure oil to the pressure chamber of the main piston via a pressure compensator, and the pressure A second oil passage that guides the pressure oil through the sound pattern of the chamber, a sub-piston that is located on the opposite side of the main piston and presses in a direction to increase the amount of eccentricity, and a sub-pressure chamber of the sub-piston that directs the pressure oil discharged from the pump. A variable discharge amount vane pump having a third oil passage that leads the pressure oil in the pressure chamber to the pressure chamber. A variable discharge amount vane pump characterized in that a surge absorption valve is arranged in conjunction with a bypass oil passage leading to a valve device, and a drain oil passage guiding the control pressure oil from the valve device to a tank when the valve device is opened. (2) The variable discharge amount vane pump according to claim 1, wherein the third oil passage is provided through a throttle valve element. (3) The variable discharge amount pump according to claim 1, wherein the oil passage and the bypass oil passage are in communication with each other. (4) The variable discharge amount pump according to claim 1, wherein the bypass oil passage is provided with an IJ IJ-7 valve operated by the valve device. (5) The variable discharge amount pump according to claim xi, wherein the pressure oil in the pressure chamber is guided to the small piston via a throttle valve that throttles only in the backward direction. (6) The variable valve according to claim 1, wherein the valve device has a poppet that is biased in a closing direction by a spring, and the poppet is a valve that is opened by the small piston against the spring. Discharge pump. (7) The variable valve according to claim iJ, wherein the valve device has a spool that is biased in a closing direction by a coil spring, and the spool valve is opened by the small piston against the coil spring. Discharge pump.