JP2006348794A - Flow control valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow control valve preventing cavitation in a pump chamber even when delivery pressure of an oil pump is high speed and low pressure. <P>SOLUTION: A first pressure receiving surface 12 is provided on one end of a spool 11 of the flow control valve 1 and a second pressure receiving surface 13 having wide area than the first pressure receiving area 12 is provided on another end, hydraulic pressure (hydraulic pressure P1 before restriction, line pressure PL) before and after a restriction 5 is applied on the first pressure receiving surface 12 and the second pressure receiving surface 13 respectively. The flow control valve 1 changes orifice flow rate Qorf according to high and low of line pressure PL and orifice flow rate Qorf at a time of low line pressure PL gets small as compared to that at a time of high line pressure PL. Consequently, even if the oil pump 2 rotates at high speed, line pressure PL is low and cavitation tends to easily occur, large quantity of oil can be supplied into the pump chamber and cavitation can be surely prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flow rate control device that controls the discharge flow rate of an oil pump.

Among the oil discharged from the discharge port of the oil pump, a flow control device that prevents excess cavitation from returning to the suction port side to prevent cavitation is disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-182664.
This flow control device is provided with a throttle (orifice) in a discharge circuit through which pressurized oil flows and communicates with a discharge port of an oil pump, and a first port that communicates with a circuit before the throttle of the discharge circuit on one end side. The spool hole having the second port communicating with the circuit after the throttle of the discharge circuit on the other end side of the spool hole and the third port communicating with the suction circuit of the oil pump, and the hydraulic pressure before throttling acts on the one end side A spool having a first pressure receiving surface and a second pressure receiving surface having the same area as the pressure receiving surface, and a biasing force acting on the spool from the other end side to one end side. And a flow control valve having a spring to open and close the third port according to the differential pressure before and after the throttling, and operate to discharge excess oil to the suction circuit side.

At this time, the flow control valve operates with the characteristics shown in FIG. That is, as the number of revolutions of the oil pump increases and the discharge flow rate of the oil pump increases, the flow rate discharged to the suction circuit side is increased so that the orifice flow rate becomes a substantially constant value. As a result, the oil (excess oil) discharged from the flow control valve to the suction circuit side is returned to the suction port, and the effect of this returned oil enhances the effect of charging the oil into the pump chamber of the oil pump. This prevents cavitation in the oil intake process.
JP 2001-182664 A

However, in the flow control device of Patent Document 1, the oil pressure receiving surface of the flow control valve is set to be the same, and the orifice flow rate depends on only the rotation speed of the oil pump, regardless of the oil pressure of the discharge circuit of the oil pump. Because of the increase and decrease, there are the following problems.
In general, when the oil pressure in the discharge circuit of the oil pump is high, the amount of oil leak from, for example, a seal portion increases as compared with the case where the oil pressure is low. For this reason, the characteristics of the orifice flow rate are set so that the oil amount balance on the downstream side of the orifice is established on the basis of when the hydraulic pressure of the discharge circuit is high. Therefore, when the oil pressure in the discharge circuit of the oil pump is low, the flow rate of the orifice supplied to the downstream side of the orifice is generally excessive, resulting in deterioration of fuel consumption.
Further, in general, cavitation tends to occur in the pump chamber when the oil pump operates in a high rotation region and a low hydraulic pressure in the discharge circuit.
However, when the above-described flow control device is in a low hydraulic pressure state, as described above, although the oil is excessively supplied to the downstream side of the orifice, the amount of excess oil returned to the pump suction circuit is small. Under such circumstances, there has been a problem that the amount of oil sucked by the oil pump is insufficient, cavitation occurs in the pump chamber, and the durability of the components of the oil pump is deteriorated by erosion.

  Accordingly, in view of such problems, the present invention provides a flow rate control device that prevents excessive supply of orifice flow rate oil pressure and prevents cavitation in the pump chamber even when the oil pressure of the discharge circuit of the oil pump is low. With the goal.

  The present invention controls the flow rate of oil flowing through a discharge circuit that communicates with a discharge port of an oil pump, and recirculates excess oil in the discharge circuit as return oil to a suction circuit that communicates with a suction port of the pump. In the flow rate control device having the control means, the flow rate control means has a higher return oil flow rate as the hydraulic pressure of the discharge circuit is lower when the oil pump is compared with the same pump speed in a region where the oil pump is higher than a predetermined speed. It was assumed to be configured to operate as follows.

According to the present invention, in the region where the oil pump is at a predetermined rotation speed or higher, the flow rate control means increases the amount of return oil to the suction circuit when compared at the same rotation speed as the hydraulic pressure of the discharge circuit decreases. Therefore, it is possible to prevent excessive hydraulic pressure from being supplied to the downstream side when the discharge circuit is at a low pressure, and to generate cavitation that causes the oil pump to rotate at a high speed and the oil pump discharge circuit to have a low hydraulic pressure. Even under easy circumstances, a large amount of oil can be supplied into the pump chamber via the suction circuit, so that cavitation can be reliably prevented.
On the other hand, if the oil pressure in the discharge circuit, where the amount of oil leakage increases on the downstream side of the oil pump, is high, reducing the amount of return oil causes the oil leakage to be insufficient on the downstream side of the oil pump. The amount of oil that is not present can be supplied to the downstream side of the oil pump.

Next, embodiments of the present invention will be described by way of examples.
In this embodiment, the flow rate of oil discharged from the vane pump that generates the line pressure of the automatic transmission is controlled by the flow rate control valve.
FIG. 1 is a diagram showing a hydraulic circuit in which a flow control valve is applied to a discharge circuit communicating with a discharge port of a vane pump.
The oil accumulated in the oil pan 7 is sucked from the suction port 3A through the suction circuit 3 by the vane pump 2 and pressurized in the vane pump 2, and then discharged from the discharge port 4A to the discharge circuit 4.
The vane pump 2 is a so-called balanced vane pump, and includes a cam ring 22 having an inner peripheral surface having a substantially elliptical cross section, a rotor 20 disposed inside the cam ring 22 and driven by the rotational force of the engine, It comprises a plurality of vanes 21 protruding from the periphery.

The vane 21 is movable in the diameter direction of the rotor 20. When the vane pump 2 is operated, the rotor 20 rotates in the cam ring 22 with the tip of the vane 21 contacting the inner peripheral surface of the cam ring 22.
The vane pump 2 includes two suction ports 3A for sucking oil and drawing them into the cam ring 22, and the suction circuit 3 is connected to each suction port 3A.
The vane pump 2 includes two discharge ports 4A for discharging pressurized oil to the outside of the cam ring 22, and a discharge circuit 4 is connected to each discharge port 4A.
As the configuration of the vane pump 2, a known one can be used.

The discharge circuit 4 is provided with a throttle 5 (flow rate control means) and a flow rate control valve 1 (flow rate control means) in order to control the oil discharge flow rate from the vane pump 2.
As shown in FIG. 2, the flow control valve 1 has a first port 30A connected to the discharge circuit 4 portion before throttling on one end side, and a second port 30B connected to the discharge circuit 4 portion after throttling on the other end side. , A spool hole 30 having a third port 30C connected to a suction return circuit communicating with the suction circuit 3, and a first pressure receiving surface 12 on one end side and the other end side movably inserted in the spool hole 30 respectively. The spool 11 includes a second pressure receiving surface 13 and a spring 10 that applies a biasing force Fsp to the second pressure receiving surface 13 from the other end side to the one end side in the spool hole 30.
The hydraulic pressure before being throttled by the throttle 5 (hereinafter referred to as pre-throttle hydraulic pressure P1) acts on the first pressure receiving surface 12 of the spool 11 of the flow control valve 1, and the second pressure receiving surface 13 is throttled by the throttle 5. The post-throttle hydraulic pressure (hereinafter referred to as line pressure PL) acts, and the second pressure receiving surface 13 is set to have a larger area than the first pressure receiving surface 12.

The flow control valve 1 acts to return the surplus oil in the input pre-throttle hydraulic pressure P1 to the suction port 3A through the suction return circuit 6 and the suction circuit 3, and changes the amount of surplus oil to be returned to the suction return circuit 6. By controlling this, the flow rate of oil passing through the throttle 5 is controlled.
The oil returned from the suction return circuit 6 to the suction circuit 3 generates a so-called supercharge effect that pushes the oil into the vane pump 2 and prevents cavitation in the oil suction process of the vane pump 2.

Oil pressurized by the vane pump 2 and controlled in flow rate by the throttle 5 and the flow control valve 1 is supplied as a line pressure PL to the clutch / brake 9 in the automatic transmission.
Here, an automatic transmission controller (not shown) determines a necessary line pressure PL value according to the running state of the vehicle, the output torque of the engine, and the like.
The solenoid valve generates a solenoid pressure (SOL pressure) based on the determined value of the line pressure PL, and applies the solenoid pressure to the relief valve 8.
The hydraulic pressure value of the line pressure PL supplied to the clutch / brake 9 is controlled by the relief valve 8 that operates according to the solenoid pressure.

Next, the detailed configuration of the flow control valve will be described.
2A to 2C show changes in the state of the flow control valve 1. FIG.
2A shows a state in which the suction return circuit 6 is closed, FIG. 2B shows a state in which the suction return circuit 6 starts to open, and FIG. 2C shows a state in which the suction return circuit 6 is opened. Shows the state of fully open.
The pre-throttle hydraulic pressure P1 before being throttled by the throttle 5 discharged from the vane pump 2 is applied to the left end (first pressure receiving surface 12) of the spool 11 provided in the flow control valve 1 in FIG. The line pressure PL after being squeezed by the throttle 5 is applied to the right end (second pressure receiving surface 13) of the spool 11 in FIG.

When the pre-throttle hydraulic pressure P1 increases and overcomes the total force of the line pressure PL and the spring biasing force Fsp, the spool 11 moves to the right in FIG. 2A, and is shown in FIG. Thus, the suction return circuit 6 starts to open.
When the pre-throttle hydraulic pressure P1 further increases, the spool 11 further moves to the right in FIG. 2B, and the suction return circuit 6 is completely opened (state shown in FIG. 2C).
When the suction return circuit 6 is thus opened, the discharge circuit 4 and the suction return circuit 6 communicate with each other, and the oil of the pre-throttle hydraulic pressure P1 flows into the suction return circuit 6 as surplus oil.
Excess oil flowing into the suction return circuit 6 is returned to the suction port 3A of the vane pump 2 through the suction circuit 3.

When the pre-throttle hydraulic pressure P1 decreases, the spool 11 moves to the left in FIG. 2C to close the suction return circuit 6, and the hydraulic pressure flow to the suction return circuit 6 is interrupted.
In this way, the flow rate control valve 1 controls the flow rate of oil passing through the throttle 5 in accordance with the pressure difference between the hydraulic pressures before and after the throttle 5 (pre-throttle hydraulic pressure P1 and line pressure PL).

Next, the flow rate of the orifice passing through the throttle 5 will be described.
FIG. 3 shows a schematic diagram of the flow control valve 1.
Here, the pressure receiving area of the first pressure receiving surface 12 is A1, and the pressure receiving area of the second pressure receiving surface 13 is A1 + A2.
The force acting on the spool 11 can be expressed by the following equation.

となる。
これにより絞り前油圧Ｐ１とライン圧ＰＬとの差圧ΔＰは、ライン圧ＰＬの影響を受けて変化する。
すなわち図４に示すように、ライン圧ＰＬが高い時には差圧ΔＰも高くなり、ライン圧ＰＬが低い時には差圧ΔＰも低くなる。 Moreover, when Formula 1 is converted as ΔP = P1−PL,

It becomes.
As a result, the differential pressure ΔP between the pre-throttle hydraulic pressure P1 and the line pressure PL changes under the influence of the line pressure PL.
That is, as shown in FIG. 4, when the line pressure PL is high, the differential pressure ΔP also increases, and when the line pressure PL is low, the differential pressure ΔP also decreases.

なお、ｃは流量係数、Ａは絞り５の断面積、ρはオイル密度とする。
式３より、差圧ΔＰが大きくなると、オリフィス流量Ｑｏｒｆは増加する。
したがって、式２と式３とより、差圧ΔＰが大きくなる、すなわちライン圧ＰＬが高くなると、絞り５を通過するオリフィス流量Ｑｏｒｆは多くなる。 The orifice flow rate Qorf passing through the throttle 5 can be expressed by the following equation.

Note that c is a flow coefficient, A is a cross-sectional area of the throttle 5, and ρ is an oil density.
From Equation 3, as the differential pressure ΔP increases, the orifice flow rate Qorf increases.
Therefore, from Equation 2 and Equation 3, when the differential pressure ΔP increases, that is, when the line pressure PL increases, the orifice flow rate Qorf passing through the throttle 5 increases.

If the flow rate of oil discharged from the vane pump 2 (flow rate flowing on the vane pump 2 side of the throttle 5) is the pump discharge flow rate Qpump, and the flow rate of oil flowing from the flow control valve 1 to the suction return circuit 6 is the return circuit flow rate Qrtrn, The formula holds.

Next, the orifice flow rate Qorf and the return circuit flow rate Qrtrn passing through the throttle 5 of the flow control valve 1 of the present invention at a predetermined number of revolutions will be considered based on the formulas 2 to 4.
If the line pressure PL increases, the differential pressure ΔP increases. Therefore, the orifice flow rate Qorf increases and the return circuit flow rate Qrtrn flowing to the suction return circuit 6 decreases.
Therefore, when the line pressure PL is high, the amount of oil leaked on the downstream side of the throttle 5 is large. Therefore, it is necessary to increase the orifice flow rate Qorf passing through the throttle 5, but the flow control valve 1 has a line pressure PL of When the flow rate is high, the return circuit flow rate Qrtrn can be reduced to increase the orifice flow rate Qorf, and an insufficient oil flow rate in the clutch, brake, etc. can be prevented.

On the other hand, if the line pressure PL decreases, the differential pressure ΔP decreases. Therefore, the orifice flow rate Qorf decreases, and the return circuit flow rate Qrtrn flowing to the suction return circuit 6 increases.
Therefore, when the line pressure PL is low, the amount of oil leaked on the downstream side of the throttle 5 is small. Therefore, it is necessary to reduce the orifice flow rate Qorf passing through the throttle 5 as compared with the case where the line pressure is high. When the line pressure PL is low, the valve 1 can increase the return circuit flow rate Qrtrn to decrease the orifice flow rate Qorf, thereby preventing deterioration of fuel consumption.

  Further, the return circuit flow rate Qrtrn flowing from the flow control valve 1 to the suction return circuit 6 can be increased by reducing the orifice flow rate Qorf passing through the throttle 5, and particularly at a high pump speed and a low hydraulic pressure of the line pressure PL. The efficiency of the oil charging effect in the oil suction process of the vane pump 2 can be increased, and the occurrence of cavitation can be further prevented.

Next, the relationship between the pump speed and the orifice flow rate Qorf will be described with reference to the drawings.
FIG. 5 shows the relationship between the pump speed and the orifice flow rate Qorf.
As the rotational speed of the rotor 20 increases, the pump discharge flow rate Qpump also increases.
Until the flow control valve 1 is operated, the discharge circuit 4 and the suction return circuit 6 are not in communication (the state shown in FIG. 2A), so that the pump discharge flow rate Qpump = orifice flow rate Qorf.

  When the rotational speed of the rotor 20 of the vane pump 2 increases to a predetermined rotational speed N1, the pump discharge flow rate becomes a predetermined amount or more, and the flow rate control valve 1 becomes operable (the spool 11 moves and the discharge circuit 4 and the suction return circuit). 6 can communicate with each other). In the region of the N1 rotation speed or higher, when the return circuit flow rate Qrtrn flows through the suction return circuit 6 according to the line pressure PL, the rising gradient of the orifice flow rate Qorf becomes small.

Here, when the line pressure PL is low, the spool 11 changes from the state shown in FIG. 2A to the state shown in FIG. 2B at a lower rotational speed than when the line pressure PL is high. And change.
Therefore, when the line pressure PL is low, the flow control valve 1 can be operated from the time when the rotational speed of the rotor 20 is lower than when the line pressure PL is high.
FIG. 5 shows the change characteristic of the orifice flow rate Qorf when the line pressure PL is the lowest value within the control range as the low pressure orifice flow rate Qorf_l, and the change of the orifice flow rate Qorf when the line pressure PL is the highest value within the control range. The characteristic is shown as orifice flow rate Qorf_h at high pressure. That is, the flow rate control valve 1 of the embodiment of the present invention operates so that the orifice flow rate Qorf takes a flow rate between the low pressure orifice flow rate Qorf_l and the high pressure orifice flow rate Qorf_h according to the line pressure PL.

  Further, both the low-pressure orifice flow rate Qorf_l and the high-pressure orifice flow rate Qorf_h increase after the flow control valve 1 is actuated. This increase is caused by the biasing force Fsp of the spring 10 biasing the spool 11, This is because it changes depending on the compression level of 10. If the urging force Fsp is constant, the orifice flow rate is constant after the flow control valve 1 is actuated.

  As shown in FIG. 5, even if the rotational speed of the rotor 20 of the vane pump 2 is the same when the line pressure PL is high and low, the return circuit flow rate is the difference between the pump discharge flow rate Qpump and the orifice flow rate Qorf. Qrtrn is smaller when the line pressure PL is higher (the high-pressure return flow rate Qrtrn is smaller) and more when the line pressure PL is lower (the low-pressure return flow rate Qrtrn is larger).

Therefore, as described above, when the line pressure PL having a large leak amount is high, the return flow rate Qrtrn can be reduced and the orifice flow rate Qorf passing through the throttle 5 can be increased.
Further, even if the orifice flow rate Qorf is set so that the oil amount balance is established when the line pressure PL has a large amount of leakage, the orifice flow rate Qorf passing through the throttle 5 is decreased and the increased return flow rate is set when the line pressure PL is low. Since Qrtrn can be supplied to the vane pump 2, it is possible to prevent an insufficient amount of oil when the line pressure PL is high, and an excessive supply of orifice flow when the line pressure PL is low, thereby preventing deterioration of fuel consumption. Further, the cavitation of the vane pump 2 can be further prevented even at a high pump speed at which cavitation is likely to occur and at a low line pressure PL.

In the present embodiment, the first pressure receiving surface 12 is provided at one end of the spool 11 of the flow control valve 1 and the second pressure receiving surface 13 having a larger area than the first pressure receiving surface 12 is provided at the other end. By applying the hydraulic pressures before and after the throttle 5 (pre-throttle hydraulic pressure P1, line pressure Pl) to the first pressure receiving surface 12 and the second pressure receiving surface 13, respectively, the flow control valve 1 is connected to the vane pump 2 as shown in FIG. When the comparison is made at the same rotation speed in the region of the predetermined rotation speed N1 or more, the orifice flow rate Qorf varies depending on the line pressure PL, and the return flow rate is lower when the line pressure PL is low than when the line pressure PL is low. Qrtrn increases.
Accordingly, since a large amount of oil can be supplied into the pump chamber when the line pressure PL is low, supply of an excessive orifice flow rate when the line pressure PL is low can be prevented, fuel consumption can be prevented, and cavitation can be prevented. The cavitation of the vane pump 2 can be reliably prevented even when the pump is easily rotated at a high speed and the line pressure PL is low.

On the other hand, when the line pressure PL at which the amount of oil leakage increases in the clutch / brake 9 is high, the amount of return circuit flow rate Qrtrn is reduced compared with the time when the line pressure PL is low, so that the oil is insufficient due to oil leakage. An orifice flow rate Qorf that does not occur can be supplied to the clutch / brake 9. (Effects corresponding to claim 1 above)
Furthermore, since the area of the second pressure receiving surface is set larger than that of the first pressure receiving surface, the return circuit flow rate Qrtrn and the orifice flow rate Qorf are changed according to the level of the line pressure PL. Appropriate flow rate control can be performed without design changes, addition of parts, or complicated control. (Effects corresponding to claim 2)

In this embodiment, the oil pump subject to flow control by the flow control valve 1 has been described using the vane pump 2 that generates the line pressure of the automatic transmission. However, other than this, for example, a pump used in a power steering device It is also possible to control the discharge flow rate of an oil pump used in other devices, such as controlling the discharge flow rate of the oil pump.
Also, the type of oil pump may be other than the vane pump.

Furthermore, as another example, instead of the flow control valve 1 including the pool 11 having pressure receiving surfaces of different sizes, for example, an electromagnetic valve whose opening / closing is controlled based on an instruction from the electronic control unit may be used. it can.
Also in this case, when the line pressure PL is high, the electronic control unit controls the solenoid valve in a direction in which the return circuit flow rate decreases. Control in many directions.
As a result, when the line pressure of the oil pump is low as in the above embodiment, the orifice flow rate can be reduced, so that deterioration of fuel consumption can be prevented. Moreover, since the return flow rate can be increased by that amount, cavitation can be reliably prevented even in a situation where cavitation is likely to occur at high pump rotation and low line pressure PL. Even when the line pressure PL is high, a sufficient amount of oil can be supplied to the clutches and brakes. (Effects corresponding to claim 1)

It is a figure which shows the Example in this invention. It is a figure which shows the change of the state of a flow control valve. It is a schematic diagram of a flow control valve. It is a graph which shows the relationship between line pressure and differential pressure. It is a figure which shows the relationship between the rotation speed of an oil pump, and an orifice flow rate. It is a figure which shows the relationship between the rotation speed of the oil pump in a conventional flow control valve, and an orifice flow rate.

Explanation of symbols

1 Flow control valve (Flow control means)
2 Vane pump (oil pump)
3 Suction circuit 4 Discharge circuit 5 Restriction (flow control means)
6 Suction return circuit 7 Oil pan 8 Relief valve 9 Clutch, brake, etc. 10 Spring 11 Spool 12 First pressure receiving surface 13 Second pressure receiving surface 20 Rotor 21 Vane 22 Cam ring 30 Spool hole 30A First port 30B Second port 30C Third port P1 Hydraulic pressure before throttle PL Line pressure (Hydraulic pressure after throttle)

Claims (2)

Control the flow rate of oil flowing through the discharge circuit communicating with the discharge port of the oil pump,
In the flow control device comprising flow control means for returning the excess oil in the discharge circuit as return oil to the suction circuit communicating with the suction port of the pump,
The flow rate control means operates so that the flow rate of the return oil increases as the hydraulic pressure of the discharge circuit is lower when the oil pump is compared at the same oil pump speed when the oil pump is at a predetermined speed or higher. A flow control device characterized by that. The flow rate control means is
A diaphragm provided in the discharge circuit;
A spool having a first port connected to the discharge circuit before throttling on one end side, a second port connected to the discharge circuit after throttling on the other end side, and a third port connected to the suction circuit A hole, a first pressure-receiving surface from which the oil before throttling of the discharge circuit acts as a pre-throttle hydraulic pressure from the first port, and an oil after throttling of the discharge circuit from the second port after the throttling And a second pressure receiving surface having a larger area than the first pressure receiving surface, and a spool provided in the spool hole, and the spool from the other end side to the one end side direction. An elastic member for applying an urging force, and a flow control valve provided with
2. The operation according to claim 1, wherein the flow control valve operates such that the lower the post-throttle hydraulic pressure is, the greater the oil flow rate of the discharge circuit before the throttling is discharged from the third port. Flow control device.

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