JPH0366974A - Flow detecting valve - Google Patents

Abstract

PURPOSE:To increase clutch pressure as commanded by a controller by providing a flow detecting valve additionally with a second signal oil pressure port for feeding the flow from a pressure control valve to an orifice through a check valve. CONSTITUTION:Oil from a pressure control valve 3 by the excitation of a proportional solenoid flows into oil chambers 26, 27 through the signal oil pressure port 14 of a flow detecting valve 4 and further into an oil chamber 25 through a check valve 15, a signal oil pressure port 16, the oil chamber 26 and an orifice 28, and a spool 12 moves to the left against a spring 24 by the pressure difference between the oil chambers 25, 26 to fill a clutch 1 with oil from the oil chamber 25. At this time, the spool 12 is not in contact with a detecting pin 29. When the filling of oil to the clutch 1 starts, pressure difference becomes small, so that the spool 12 moves to the right to open a spool hole 10 between the oil chambers 27, 28, and the right end of the spool 12 is brought into contact with the detecting pin 29, thus detecting the termination of filling. The clutch pressure can be thus increased gradually as commanded by a controller.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flow rate detection valve used when filling a hydraulic actuator with oil, and is particularly applicable to large hydraulic multi-disc clutches for transmissions of large construction machines. Connect to the flow rate detection valve of the capacity actuator.

[Prior Art] When controlling the clutch pressure of a transmission equipped with a large-capacity clutch pack such as a dump truck, a flow rate detection valve is used to shorten the time for filling the clutch pack with oil (filling time). An electronic hydraulic control system is used. As shown in FIGS. 7 and 8, this device consists of a pressure control valve 3 that is activated by an electric command from a controller 6, and a flow rate detection valve that is activated by a differential pressure across an orifice 28 formed in the hydraulic circuit to the clutch 1. 4, and when changing gears, the pressure control valve 3 is opened to allow oil from the hydraulic pump 7 to flow into the flow rate detection valve 4,
The resulting differential pressure across the orifice 28 opens the flow rate detection valve 4, allowing oil from the hydraulic pump 7 to flow into the clutch 1 via the flow rate detection valve 4. clutch 1
When the valve is filled with oil, the flow rate detection valve 4 is closed by the hydraulic pressure generated by the difference in the pressure receiving area of the spool 12 of the flow rate detection valve 4, and then the command value applied to the pressure control valve 3 is gradually increased to gradually increase the clutch pressure. I'll let it happen.

However, this valve structure has the following drawbacks as shown in FIG.

(1) At the same time as the pressure control valve is actuated by the command current, oil is supplied to the output hydraulic port to the clutch via the orifice, so that the flow rate detection valve is actuated. After that, when the supply pressure from the pressure control valve decreases, the supply pressure Pl drops rapidly even though oil is directly supplied from the hydraulic pump (section A in FIG. 9(C)).

(2) After the flow rate detection valve closes, the supply pressure Pl drops to almost zero (section B in Figure 9(C)), which causes the clutch pressure to drop (as shown in Figure 9(b)). C part)
. Further, thereafter, the time it takes for the supply pressure Pl to reach the target fill pressure PF becomes longer, and as a result, the time tf until the clutch pressure reaches the target fill pressure becomes longer, causing a problem in responsiveness during gear shifting.

(3) After the flow rate detection valve closes, the detection bottle 29 and the spool 12 come into contact with each other and become electrically conductive, thereby decreasing the sensor voltage (potential at point a). With this voltage drop, the controller 6 determines that filling has ended, but the actual clutch pressure has not reached the target filling pressure. That is, the apparent filling time tfs and the actual filling time 1. It's quite different from that. As a result, the controller that has obtained the apparent filling signal tries to gradually increase the clutch pressure by gradually increasing the command current of the pressure control valve. However, since the actual clutch chamber is not filled, the clutch pressure is not gradually increased as instructed by the controller. As a result, problems such as shift shock occur.

The cause of the above drawback is considered to be as follows.

(1) After the pressure control valve is activated by the command current (trigger command), oil flows to the flow rate detection valve, and the flow rate detection valve opens,
This command current is lowered to an appropriate initial level (target fill pressure level), and the system waits until the filling is completed. At this time, the output hydraulic port of the pressure control valve partially communicates with the tank port, so the oil that flows directly from the hydraulic pump to the flow detection valve flows back to the output hydraulic port of the pressure control valve and flows out to the tank port. Put it away. Further, as the pressure at P+ increases, the spool of the pressure control valve moves in the closing direction due to pressure feedback, increasing the opening to the tank port and increasing the flow rate to the tank. As a result, the supply pressure P+ drops (the cause of part A).

(2) After the flow rate detection valve opens, when the flow rate to the clutch decreases, the left side closes due to the pressure difference before and after the orifice. As mentioned in (1) above, at the moment of closure, the pressure control valve is widely connected to the tank port. On the same left, a command current for the target fill pressure is flowing, but due to the sudden pressure drop, the target pressure does not reach the target pressure immediately.

In other words, the supply pressure P+ drops to nearly zero due to the response delay of the pressure control valve (the cause of parts B and C).

(3)・Once the supply pressure Pl drops to near zero,
Due to the time delay until the pressure rises to the target value, the time (actual boiling time tt) for the clutch pressure Pc to reach the target pressure PF becomes longer. As a result, the apparent filling time 1B and the actual filling time 1f differ greatly, making it impossible to perform optimal control.

In order to solve the above problem, as shown in Figs. 10 to 12, while the flow rate detection valve 4 is inquiring, the input hydraulic pressure from the pressure control valve 3 (13) is closed, and the oil to the clutch l is supplied to the hydraulic pump. A hydraulic control device is known in which oil is supplied only from 7 through an orifice 28. The opening area of the signal hydraulic port 14 from the pressure control valve 3 of this hydraulic control device (
A p + ) and the opening area (A part 2) of the input hydraulic port 13 from the hydraulic pump 7 with respect to the spool stroke S, as shown in FIG. 12(a), 5=S
API and AP 2 overlap between 1 and S2. As a result, while this flow rate detection valve 4 is open (S
= S max) is the oil input to the clutch 1 only from the direct hydraulic pump 7)] 3 (Part A 2)
Since the oil is supplied through the orifice 28, the oil does not flow out from the tank port of the pressure control valve 3, and the disadvantage that the supply pressure Pl in front of the orifice 28 drops is solved.

[Problems to be Solved by the Invention] However, as the flow rate to the clutch decreases and the pressure difference across the orifice decreases, the spool stroke S of the flow rate detection valve decreases, and S + < S <.
When S2 is reached, the hydraulic pump pressure becomes A part 2. It reaches the output hydraulic port section of the pressure control valve via the API.

As a result, a disturbance is given to the output pressure of the pressure control valve, which had been on standby at the target pressure until then, and the drawback that the supply pressure Pl drops to near zero (section B in FIG. 13(C)) is not solved.

It is also conceivable to change the aperture characteristics shown in FIG. 12(a) to characteristics with no overlap as shown in FIG. 12(b).
In this case, if you try to supply signal pressure to open the valve and operate it,
Since the flow rate supplied to the orifice temporarily becomes zero, the spool returns without opening.

The present invention focuses on the above conventional problems, has a simple and inexpensive configuration, and has a practical filling time of 1. It is an object of the present invention to provide a flow rate detection valve that approximates the apparent filling time tfs by shortening the time, and inputs this to a controller using a filling and clutch oil pressure detection mechanism.

[Means for Solving the Problem] In order to achieve the above object, the flow rate detection valve according to the present invention has the following features:
When filling the hydraulic actuator with oil, the orifice installed in the spool, which is held neutral by the spring force, is opened by the differential pressure before and after it, allowing a large flow to flow, and when the hydraulic actuator is filled with oil, the spool receives pressure. In a flow rate detection valve equipped with a detection mechanism that moves the spool in the opposite direction to the opening direction using hydraulic pressure due to the difference in area, and detects filling and the actuator oil pressure by a switch action according to the movement of the spool, the input oil pressure is detected. A port, an output hydraulic port, a signal hydraulic port to which a signal hydraulic pressure is input to generate a differential pressure before and after the orifice and open the spool, and a second signal to which the signal hydraulic pressure is also input through a check valve. The configuration includes a hydraulic port.

[Operation] According to the above configuration, by adding the second signal hydraulic port that supplies the flow rate from the pressure control valve to the orifice via the check valve, the opening characteristics of the flow rate detection valve (API and AP 2 ) are not overlapped, the supply pressure Pl is kept within the specified range and opened (S=Sm
Since the oil from the hydraulic pump does not flow backward through the pressure control valve and into the tank during filling, the pressure drop in section A in FIG. 9(c) is eliminated. Also, while the flow rate detection valve is open and closed,
Since the pressure from the hydraulic pump does not directly reach the output hydraulic port of the pressure control valve, the pressure at the output hydraulic port can maintain the target fill pressure.

As a result, the actual filling time tf becomes shorter, and at the same time, t2 becomes tis, and the clutch pressure can be gradually increased as instructed by the controller.

[Example] Examples of the flow rate detection valve according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the hydraulic circuit configuration of an electronic clutch hydraulic control device 2 that drives a clutch 1, and includes a pressure control valve 3 that controls clutch hydraulic pressure, a flow rate detection valve 4, and a filling and clutch hydraulic pressure detection mechanism 5. It is composed of. The pressure control valve 3 is a solenoid valve controlled by a controller 6, and the detection signal S of the detection mechanism 5 is controlled by the controller 6.
is input. Further, the circuit of the hydraulic pump 7 is connected to the pressure control valve 3 and the flow rate detection valve 4.

FIG. 2 shows the internal cross-sectional configuration of the flow rate detection valve 4. As shown in FIG. The flow rate detection valve 4 has a spool hole 9 formed in the valve body 8,
10.11, and the diameters of the spool holes 10.11 are the same. A spool 12 is slidably inserted into the spool holes 9, 10, and 11 of the valve body 8, and is connected to an input hydraulic bow 13 for allowing oil to flow in from the hydraulic pump 7, and for oil to flow in from the pressure control valve 3. A signal hydraulic port 16 for allowing oil from the pressure control valve 3 to flow in through the check valve 15, and an output hydraulic port 17 for supplying oil to the clutch 1 are provided. There is. Further, a cover 18 is provided at the left end of the spool hole 9, and a cover 18 is provided at the left end of the spool hole 9.
A cover 19 is provided at the right end of each of the two.

The spool 12 has a first land 20. 2nd land 21
A spring guide 22 is fitted onto the right end shaft portion of the spool 12, and a spring 23 is interposed between the spring guide 22 and the right end cover 19. Further, a spring 24 is interposed between the window cover 18 and the left end surface 20a of the first land 20.

An oil chamber 25 is located between the cover 18 and the first land 20.
An oil chamber 26 exists between the first land 20 and the spool hole 10,
An oil chamber 27 is defined between the spool hole 10 and the second land 21, and an orifice 28 is formed in the first land 20 to communicate the oil chamber 25 and the oil chamber 26.

The pressure receiving area of the left end surface 20a of the first land 20 is A3.
, the pressure receiving area of the right end surface 20b of the first land 20 is kls
Assuming that the pressure receiving area of the left end surface 21a of the second land 21 is A2, there is A3> between these pressure receiving areas A1, A2, and A3.
There is a relationship of A I> A 2 .

The filling and clutch oil pressure detection mechanism 5 has a detection pin 2
9, this detection pin 29 is held by the cover 19 through insulating members 30 and 31 disposed on both sides of the cover 19, while passing through the thank-you part of the cover 19,
A nut 32 is screwed onto the outwardly projecting portion of the detection pin 29, and by tightening the nut 32, the detection pin 29 is fastened to the cover 19 via an insulating member 30.31.

The inner end surface of the detection pin 29 faces the right end surface of the spool 12, and the outer end thereof connects the lead wire 3 to the midpoint a of the resistors R1 and R2.
A DC voltage of, for example, 12 V is applied to both ends of the resistors R1 and R2, and the valve body 8 is grounded. Note that a drain port 34 to the tank is provided at the right end of the valve body 8.

Next, the operation will be explained. Now, when no oil pressure is applied to the oil chambers 25 and 26, the spool 1 is moved by the tension of the springs 23 and 24.
2 maintains a neutral state and enters the oil chamber 3 through the input hydraulic port 13.
The oil that has flowed into the oil chamber 5 remains in the oil chamber 35 because the spool 12 is closed.

In this state, when the proportional solenoid 36 of the pressure control valve 3 shown in FIG. 16 and flows into the oil chamber 26. This oil flows into the oil chamber 25 through the orifice, and flows into the clutch 1 through the output port 17. At this time, a pressure difference is generated between the oil chamber 26 and the oil chamber 26 due to the orifice 28 .

If the pressure in the oil chamber 26 is Pl and the pressure in the oil chamber 25 is P2, P r > P 2 and P 2 = 0, so (A + -A 2 ) P 1 > A 3 P 2
・・・・◆・・・・・・・・・■(AI A2) PI>
The relationship O◆・・・◆・・・・・・・・・・■' holds true.

In this way, the spool 12 is moved by the spring 2 due to the force according to the equation ■'.
Move to the left against 4. Therefore, the spool 12 is
The spool hole 10 is closed at the land 210 part, but the oil from the pressure control valve 3 is passed through the check valve 15, the signal hydraulic port 16,
It flows into the clutch 1 through the orifice 28. When the spool 12 moves further to the left, it opens at the land 20 and the oil from the hydraulic pump enters the oil chamber 35 and flows into the oil chamber 2.
6, passes through the orifice 28, passes through the oil chamber 25, and flows into the clutch 1. This flow continues until clutch 1 is filled with oil.

At this time, the spool 12 is not in contact with the detection pin 29. Therefore, when the flow rate detection valve 4 is filling the clutch l, the spool 12 is not in contact with the detection bottle 29, so there is a resistance R1 at point a as shown in FIG. 3(a).
, R2 appears. Then, when the clutch 1 starts to be filled with oil, the flow of oil to the clutch 1 through the orifice 28 decreases, so the differential pressure (PI
F2) also becomes smaller. Here, if the spring constant of the spring 23 is 1, the installation load is Fl, the spring constant of the spring 24 is 2, and the installation load is F2, then F 2 + A s P 2 + A 2 P + >
A + P +・・・・・・・・・■Therefore, A 3 P 2 + (A 2- A + ) P +
> −F 2...■'Here, if the mounting load F2 of the spring 24 is set to a value that can be ignored compared to the hydraulic pressure,
■ Obtain the following equation from the equation.

Therefore, when the pressure ratio between F2 and Pl exceeds the value of formula 0, the spool 12 moves to the right due to the hydraulic pressure caused by the difference in pressure receiving area, and the land 20 of the spool 12 connects the oil chamber 35 with the oil chamber. 26.

At the same time, the land 21 is used to open the spool hole 10 between the oil chamber 27 and the oil chamber 26.

When the differential pressure (PI F2) further decreases, if the stroke amount from the spool installation state to the detection pin 29 is X, (2X to F2-) + A3P2 + A2PI > AIP++ (
F+++X)・・・・・・・・・・・・・・・・・・
...■Therefore, A3P2+ (A2 AI) PI>PI F2+
(k++ R2)X ・・・・・・・・・・・・・・・
...■' Therefore, when PI and F2 reach values that satisfy formula 02, the spool 12 moves further to the right due to the hydraulic pressure caused by the difference in pressure receiving area, and the right end surface of the spool 12 touches the detection pin 29. Contact. Since the spool 12 is in contact with the valve body 8, point a becomes the ground potential, and no voltage appears at point a (see FIG. 3(a)).

In this way, it can be detected that the filling has been completed.

When the flow rate detection valve 4 closes, the pressure control valve 3 starts regulating the pressure, and the pressure of the clutch 1 is controlled.

At this time, since the spool 12 remains in contact with the detection bottle 29, the potential at point a remains zero.

Therefore, when pressure is applied to clutch 1, the potential at point a is always zero. When the pressure in clutch 1 disappears, a potential appears at point a. The above relationship is shown in FIG.

In FIG. 3, (a) is the command current to the pressure control valve 3 and the voltage at point a of the detection mechanism 5, (b) is the clutch pressure Pc, (C) is the supply pressure P+ (the pressure immediately before the orifice 28) and The stroke S of the spool 12 (d) is the respective characteristic of the output pressure Po of the pressure control valve.

In this embodiment, a clutch hydraulic control device 2 equipped with the detection mechanism 5 is provided for each clutch of each speed stage, and the outputs of the plurality of detection mechanisms 5 are inputted to a controller 6 as shown in FIG. I try to do that. The controller 6 monitors the outputs of the plurality of detection mechanisms 5, and determines the completion of filling and the presence or absence of double engagement based on the monitoring results.

In order to reduce the torque-off, for example, when attempting to shift from 1st speed to 2nd speed, the clutch pressure may be built up using the builing end signal as a reference point, as described above. In this way, just before the 1st gear clutch is disengaged, the 2nd gear clutch is filled with oil, and at the same time as the 1st gear clutch is disengaged, the clutch pressure is built up based on the filling completion signal from the flow rate detection valve 4. For example, as shown in FIG. 5, torque-off due to filling time tf can be eliminated, so torque-off during gear shifting can be eliminated.

Furthermore, as shown in FIG. 6, crossover control is also possible in which the 2nd speed clutch is engaged while the 1st speed clutch is disengaged, making it possible to realize a very smooth shift operation. However, when clutch crossover control is implemented, care must be taken to avoid double engagement of the clutch. However, as described above, since the clutch pressure can be detected by the spool 12 of the flow rate detection valve 4, it is possible to monitor which clutch is being applied with steady pressure based on this clutch pressure detection signal. Further, while monitoring this signal, the valve command of the controller 6 may be determined so as not to cause double engagement.

In this embodiment, a case where the present invention is applied to a hydraulic multi-disc clutch of a transmission will be explained. However, the present invention is not limited to this, and the present invention can also be used when filling oil in other single-acting cylinders, etc. can.

[Effects of the Invention] As explained above, according to the present invention, by adding the second signal hydraulic port that supplies the flow rate from the pressure control valve to the orifice via the check valve, the opening of the flow rate detection valve can be controlled. Even when the characteristics do not overlap, the oil pressure just before the orifice (supply pressure) is kept within the specified range before it opens, so the oil from the hydraulic pump will not flow backwards through the pressure control valve and into the tank. There is no pressure drop during filling. Also, even when the flow detection valve is open or closed, the pressure from the hydraulic pump does not directly reach the output hydraulic port of the pressure control valve, so the pressure at the output hydraulic port can maintain the target fill pressure. .

As a result, the actual filling time is shortened and at the same time becomes a value close to the apparent filling time, and the clutch pressure can be gradually increased as instructed by the controller with a simple and inexpensive configuration.

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram of an electronic clutch hydraulic control device according to an embodiment, Fig. 2 is a sectional view of a flow rate detection valve, and Fig. 3 is a diagram showing changes in hydraulic pressure in response to commands from a controller.
) is the controller command current and the voltage of the oil pressure detection mechanism (potential at point a), (b) is the clutch oil pressure, (C) is the supply pressure just before the orifice and the spool stroke of the flow rate detection valve,
(d) shows the output pressure of the pressure control valve, respectively. Figure 4 is a diagram showing the relationship between the oil pressure detection mechanism provided in each speed clutch of the transmission and the controller, and Figure 5 is a diagram showing the relationship between oil pressure changes of the two clutches when changing gears. ,
(a) shows the 1st gear latch oil pressure, and (b) shows the 2nd gear clutch oil pressure. FIG. 6 is a diagram showing changes in oil pressure when the oil pressures of two clutches are subjected to crossover control during gear shifting, in which (a) shows the 1st speed clutch oil pressure, and (b) shows the 2nd speed clutch oil pressure. Fig. 7 is a hydraulic circuit diagram of a conventional electronic clutch hydraulic control device, Fig. 8 is a sectional view of a conventional flow rate detection valve, and Fig. 9 is a hydraulic circuit diagram of a conventional electronic clutch hydraulic control device. This figure shows changes in oil pressure, where (a) shows the controller command current and the voltage of the oil pressure detection mechanism (potential at point a), (b) shows the clutch oil pressure, and (C) shows the supply pressure just before the orifice. FIG. 10 is a hydraulic circuit diagram of a conventional improved electronic clutch hydraulic control device, FIG. 11 is a sectional view of the flow rate detection valve of FIG. 1O, and FIG. 12 is an input hydraulic port opening area from a pressure control valve. A diagram showing the opening characteristics of the input hydraulic port opening area from the hydraulic pump and the spool stroke S, (
(a) shows the case where the two overlap, and (b) shows the case where the two do not overlap. Figure 13 is the 10th
In the hydraulic control device shown in the figure, this is a diagram showing changes in oil pressure in response to commands from the controller. (a) is the controller command current and the voltage of the oil pressure detection mechanism (potential at point a), (b) is the clutch oil pressure, and (C) is the orifice. The previous supply pressure, (
d) shows the output pressure of the pressure control valve, respectively. 1...◆Clutch 2...Electronic clutch hydraulic control device 3...
...Pressure cutoff valve 4...Flow rate detection valve 5...Filling and clutch hydraulic pressure detection mechanism 6◆...◆・Controller 7...Hydraulic pump 12... ... Spool 13 ... Input hydraulic port 14.16 ... Signal hydraulic port 15 ...
・Check valve 17・・◆・Output hydraulic port 28◆・・◆・・Orifice

Claims (1)

[Claims] When filling the hydraulic actuator with oil, the orifice 28 provided in the spool 12, which is held neutrally by the spring force, is opened by the differential pressure before and after the orifice 28, allowing a large flow to flow, and when the hydraulic actuator is filled with oil, the spool A detection mechanism 5 is provided which moves the spool 12 in the opposite direction to the opening direction using hydraulic pressure due to the difference in pressure receiving area of the spool 12, and detects filling and the actuator oil pressure by a switch action corresponding to the movement of the spool 12. In the flow detection valve 4 , the input hydraulic port 13 , the output hydraulic port 17 , and the signal hydraulic port 14 to which a signal hydraulic pressure is input to generate a differential pressure before and after the orifice 28 and open the spool 12 are the same. A flow rate detection valve characterized by comprising a second signal hydraulic pressure port 16 into which a signal hydraulic pressure is input through a check valve 15.