JPH04107566U - Transmission fluid pressure control circuit - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain sufficient modulation performance not only during inching but also during gear shifting, forward/forward switching, and at low temperatures. [Structure] When switching from neutral to first forward speed, oil brought to clutch pressure by the regulating valve 2 flows to the direction conversion valve 55 and the speed conversion valve 43. The oil flowing to the direction changing valve 55 flows to the load piston 36 and gradually increases the clutch pressure of the forward clutch 31. Some of the oil flows to the flow sensing valve 38 and pushes the flow sensing spool 38a. The oil in the load piston 36 flows to the check valve 41 and its pressure is regulated. Due to the movement of the flow sensing spool 38a, the oil that was flowing to the load piston 36 flows to the direction change valve 55 and then to the forward clutch 31. At this time, the oil is held at the clutch pressure and the load piston 36 is at the modulation start position, so sufficient modulation performance can be obtained even when the transmission is switched.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention relates to a fluid pressure control circuit for a transmission in a liquid-driven vehicle such as a construction vehicle. Ru.

0002

[Conventional technology]

Transmissions (hereinafter referred to as transmissions) using hydraulic multi-disc clutches used in construction vehicles etc. When the vehicle switches forward or backward, it absorbs the shock caused by the inertia of the vehicle and prevents the vehicle from sliding. In order to obtain smooth connection characteristics, apply oil to the clutch plate in the transmission during connection. A method (hereinafter referred to as "modulate") is adopted to gradually increase the pressure and bring the clutch into a half-clutch state. ing.

0003 A means for controlling the hydraulic pressure for this clutch plate was disclosed in Utility Application No. 1-46531. It is shown.

0004 As shown in FIG. a modulating valve 4 for gradually increasing the clutch fluid pressure when the clutch 2 is connected; a load piston 16 for automatically operating the modulate valve 4; The load piston is activated by fluid pressure from the modulating valve 4 to the clutch. 16 and a flow sensing valve 14 to actuate the clutches 21 and 22. and an inching valve 17 for opening and closing the flow path to perform inching operation. The inching valve 17 is connected to the flow sensing valve 14 and the load piston 1. The check valve 2 is connected to the flow path 25 between the inching valve 17 and the inching valve 17. 6 is provided.

[0005] In addition, in the figure, 1 is the inlet port, 2 is the regulation valve, and 2a is the spool. , 2b is the chamber behind the spool, 3, 5, 6, 7, 8, 9 are the circuits, 4a is the module Toss pool, 4b is rod, 4c is chamber, 10 is speed conversion valve, 15, 18, 2 0 is the circuit, 17a is the inching spool, 17b is the spring, 19 is the direction change Valve, 27 is circuit, T is tank, P is charge pump, F is filter, Tc is In the torque converter, b, c, and d are throttles.

[0006] By configuring as described above, the modulate valve 4 can control the clutch hydraulic pressure. Raise it gradually. When the clutch oil pressure reaches the specified pressure, all circuit pressures are The clutch pressure becomes equal to the clutch pressure regulated by the rate valve 2, and the clutch is engaged.

[0007]Here, when the inching valve 17 is turned ON, the oil flowing to the forward clutch 21 is drained, and the oil pressure becomes 0 kg/cm ² .

[0008]Also, the oil that has passed through the throttle d of the flow sensing valve 14 flows to the load piston 16 and the inching valve 17, but since the inching valve 17 is in the ON position, the oil is in the inching spool 17a. The pressure is regulated by the check valve 26. That is, in the inching ON state, the oil pressure in the load piston chamber 15 is maintained at the pressure set by the check valve 26 (3 kg/cm ² in practice).

[0009] After that, when inching is turned OFF, the clutch piston is suddenly affected by high oil pressure. Filled with oil. Therefore, if the inching ON time is long, please use the clutch piston. The tank is rapidly filled with oil, which shortens fill-up time and improves tie-up times. No unevenness occurs.

0010 Next, if the inching ON time is short, load at the moment the inching is turned ON. Since the oil in the piston 16 is drained from the check valve 26, the load piston 16 moves almost to the right position, so even if the inching is turned off afterwards, it will not function normally. Jurate performance can be obtained.

[0011]

[Problem that the idea aims to solve] With the above conventional technology, it is not possible to improve the starting performance mainly during inching. Ru. However, it is difficult to change forward/forward motion, shift up, or downshift frequently in a short period of time. When going to , it is not possible to obtain sufficient modulation performance. Especially at low temperatures. This is noticeable when the oil temperature is low.

0012 In other words, frequent switching operations will ensure that the clutch piston has sufficient oil. Since oil flows again into the area where it has not drained, the oil pressure in circuit 8 does not decrease and the oil pressure in circuit 1 The flow sensing valve 14 is not pushed to the right by the oil pressure of 5. road piste Pour oil again from the flow sensing valve 14 into the area where the oil in the drain 16 is not drained. A problem occurs because of this.

[0013] In view of the above, this invention is designed not only for inching, but also for forward/forward switching, at low temperatures, etc. We aim to provide a fluid pressure control circuit that can obtain sufficient modulation performance even in purpose.

[0014]

[Means to solve the problem]

The problem solving means according to the present invention is as shown in FIG. , 34, 35 and the forward/reverse clutches 31, 32 to operate the clutches. In the fluid pressure control circuit of the transmission for moving the clutch, when the clutch is connected, Load pistons 36 and 37 for gradually increasing the fluid pressure, and the load pistons flow sensing valves 38 and 39 for actuating the valves 36 and 37; The fluid pressure to the load pistons 36, 37 is adjusted in the low sensing valves 38, 39. Check valves 41 and 42 are provided to check the pressure.

[0015]

[Effect]

In the above problem solving means, when shifting from a neutral state to forward 1st speed, the regulation The oil whose pressure has been regulated to the clutch pressure flows through the oil passage inside the flow sensing valve 38. through the direction changing load piston 36. Therefore, the clutch pressure gradually increases. It continues to rise.

[0016] Also, some of the oil enters the chamber 38b at the back of the flow sensing spool 38a. , when the clutch pressure reaches a certain set pressure, the flow sensor of the flow sensing valve 38 is activated. moving the sensing spool 38a.

[0017] Therefore, the oil in the load piston 36 is transferred to the oil path of the flow sensing spool 38a. 50, and the pressure is regulated by the check valve 41. At this time, the flow sensing Since the oil passage inside the valve 38 is opened, the oil whose pressure has been regulated to the clutch pressure flows to the clutch 31. and is held by this hydraulic pressure.

[0018] Also, for the speed stage clutches 33, 34, and 35, the above-mentioned direction change flow control is applied. Similar to the check valve 41 of the sensing valve 38, the speed stage flow sensing By regulating the pressure with the check valve 42 of the valve 39, the regular valve It is maintained by the hydraulic pressure regulated in step 2.

[0019] In this state, each load piston 36, 37 is at the starting position of the modulate. , so no matter what transmission changes are made afterwards, sufficient modulation performance ability can be obtained. Also, since the load piston pressure is maintained at low pressure, The fail-up time is short and time lag can be eliminated. Therefore, master Good modulation performance can be obtained.

[0020]

【Example】

Hereinafter, one embodiment of the present invention will be described based on the drawings.

[0021] Figures 1-A and B are transmission fluid pressure control circuit diagrams showing an embodiment of the present invention, and Figure 2 is a diagram of the present invention. The modulated waveform diagram obtained by this invention, Figure 3 is a conventional modulated waveform diagram. Ru.

[0022] As shown in the figure, the fluid pressure control circuit of the transmission according to the present invention has a hydraulic drive shaft that moves forward and backward. Fluid is supplied to latches 31, 32 and speed clutches 33, 34, 35 to achieve this. for operating the clutches 31, 32, 33, 34, 35, It is used for direction change and to gradually increase the clutch fluid pressure when the clutch is engaged. and speed gear load pistons 36, 37, and actuating the load pistons 36, 37. flow sensing valves 38 and 39 for direction change and speed stage; and an inching valve 40 for opening and closing the flow path to the piston to perform an inching operation. and into the load pistons 36, 37 in the flow sensing valves 38, 39. Check valves 41 and 42 are provided to regulate the fluid pressure.

[0023] The speed clutches include a first speed clutch 33, a second speed clutch 34 and a third speed clutch. It has a diameter of 35. And the speed at which these speed stage clutches 33 to 35 are switched The conversion valve 43 is a three-position switching valve and has five ports. And fast The degree conversion valve 43 is connected to the regular valve 2 through a flow path A.

[0024] The speed stage flow sensing valve 39 is of a two-position switching type, and Each clutch 33, 34, 35 of the speed conversion valve 43 and the speed gear load piston 37, and are connected by channels B and C. Also, the speed conversion bar Each clutch 3 is connected to the flow path B connecting the valve 43 and the flow sensing valve 39. Restrictions 45a, 45b, 45c and gates with different flow rates according to 3, 34, 35 Flow sensing valves 46a, 46b, 46c are interposed, and flow sensing is carried out from flow path B. A flow path D connected to a chamber 39b on the back side of the gas pool 39a is branched.

[0025] Then, the flow path E of the flow sensing valve 39 connects with the load piston 37. The flow sensing valve 39 is connected to the flow path C that connects the sensing valve 39. A check valve is provided on the flow path E side of 39 to open and close the flow path between the flow path E and the drain 47. A lube 42 is provided.

[0026] The check valve 42 is formed in the radial direction of the flow sensing spool 39a. and the rear end of the flow sensing spool 39a communicating with the oil passage 50. A valve chamber 52 formed in the axial direction of the spool 39a so as to communicate with the pore 51, and the valve A valve element 53 that can be freely seated and removed from a valve seat with a valve hole in a chamber 52, and the valve element 53 is urged in the seating direction. and an adjustment spring 54.

[0027] Note that the direction change flow sensing valve 38 is a speed gear flow sensing valve 38. It has the same structure as the operating valve 39.

[0028] The inching valve 40 is a two-position switching type, and has four ports. It is switched ON and OFF by a solenoid that is linked to an inching pedal, etc. It will be FF.

[0029] The inching valve 40 includes the regular valve 2 and the direction conversion valve 5. 5 through flow paths G and H. In addition, in the inching valve 40, The same structure as the check valves 41 and 42 of the flow sensing valves 38 and 39 A check valve 56 is provided.

[0030] The direction conversion valve 55 is a three-position switching valve and has six ports. A flow path is provided between the direction conversion valve 55 and the direction conversion load piston 36. A flow sensing valve 38 for direction change is provided via I and J.

[0031] The flow path J connecting the flow sensing valve 38 and the load piston 36 has a , a throttle 57 is interposed, branching from the flow path J to the inching valve 40. The flow path K connected to the check valve 56 and the flow sensing valve 38 A flow path L connected to a check valve 41 is formed.

[0032] Further, a flow path H connecting the inching valve 40 and the direction conversion valve 55 is provided with a , connected to the load piston 36 via the flow sensing valve 38 for direction change. direction change via the flow path M communicating with the flow path J and the flow sensing valve 38. A flow path N communicating with a flow path I connected to the exchange valve 55 is formed. Then, the flow path M connects to the chamber 38b on the back side of the flow sensing spool 38a. The continuous flow path O is branched.

[0033] Note that the other configurations are the same as the conventional one.

[0034] In the above configuration, when shifting from the neutral state to forward 1st speed, the tank T The inlet port of the regulation valve 2 is pumped through the filter F by the pump P. The oil that has entered the valve 1 flows through the small hole of the spool 2a of the regular valve 2 to the back of the spool. Enter the rear chamber 2b and move the spool 2a to the right in the figure to adjust the pressure. Regillet The oil whose pressure has been regulated to clutch pressure is transferred from flow paths A and G to speed conversion valves. 43 and to the inching valve 40.

[0035] Since the oil flowing to the inching valve 40 is in an inching-off state, The oil passes through the oil path in the spool of the switching valve 40 and flows into the flow paths H, M, and N. Channel H The oil that flows into the flow path I passes through the oil path in the direction conversion valve 55. This oil is It is blocked by the flow sensing valve 38 for direction change.

[0036] The oil flowing into the flow path M passes through the oil path in the flow sensing valve 38 and flows into the flow path J. It passes through the throttle 57 and flows into the chamber 36a of the direction changing load piston 36. Besides that As a result, the clutch pressure gradually increases.

[0037] In addition, a part of the oil that has flowed to the flow path M also flows to the flow path O, enters the chamber 38b on the back side of the flow sensing spool 38a, and the clutch pressure reaches a certain set pressure (18 kg/cm ² in this case). When it reaches this point, the force of the spring 54 of the flow sensing valve 38 is overcome and the flow sensing spool 38a is pushed to the right in the figure.

Therefore, the oil in the chamber 36a of the load piston 36 flows into the oil passage 50 of the flow sensing spool 38a, the pressure is regulated by the check valve 41, and the oil is drained from the valve chamber 52. The setting is 3kg/cm ² ).

At this time, the oil flowing into the flow path M is blocked by the flow sensing valve 38. Since the oil passage in the flow sensing valve 38 is opened, the oil flowing into the flow path N flows from the flow path I to the forward clutch 31 via the direction change valve 55. The oil pressure at this time is maintained at the oil pressure regulated by the regular valve 2 (20 kg/cm ² in this case).

[0040] On the other hand, the oil flowing from the flow path A to the speed conversion valve 43 is It flows to the first speed clutch 33 through the oil passage. At the same time, the oil is transferred to the speed conversion valve 4. 3 to the flow path B, passes through the check valve 46a and the throttle 45a, and reaches the speed stage. The oil passage in the flow sensing valve 39 for It flows into the chamber 37a of the tube 37. Then, the direction change flow sensing valve 3 Similarly to the check valve 41 of No. 8, check the speed stage flow sensing valve 39. The oil pressure regulated by the regulation valve 2 is held under pressure.

[0041] In this state, each load piston 36, 37 is at the starting position of the modulate. , so no matter what transmission changes are made afterwards, sufficient modulation performance ability can be obtained. Also, since the load piston pressure is maintained at low pressure, The fail-up time is short and time lag can be eliminated. Therefore, master Good modulation performance can be obtained.

[0042] Moreover, for each speed stage clutch 33, 34, 35, the throttle 45a, 45b and 45c, the clutch can be adjusted according to each speed stage as shown in Fig. 2. As the pressure P increases, the pressure inside the conventional flow sensing valves 38 and 39 shown in FIG. Compared to the hydraulic waveform controlled by one throttle d, the same modulus is applied at every speed stage. Urate performance can be obtained. In addition, in the conventional case, 1st gear is harder and 2nd gear is softer. It gives a modulated feeling.

Next, when the inching valve 40 is turned on, the oil flowing to the forward clutch 31 is drained from the flow path H through the oil path in the inching valve 40, and the oil pressure becomes 0 kg/cm ² .

[0044] Also, the oil flowing from the load piston 36 to the flow path K is inside the inching valve 40. The pressure is regulated by the check valve 41.

[0045] That is, in the inching ON state, the oil pressure in the load piston chamber 36a is maintained at the pressure set by the check valve 41. Also, regular valve The oil pressure from 2 to the flow path G from the inching valve 40 is checked by the check valve 41. The pressure is maintained higher than the set oil pressure.

[0046] After that, when inching is turned OFF, the forward clutch 31 is suddenly supplied with high oil pressure. Filled with oil. Therefore, if the inching ON time is long, please use the clutch piston. Since the tank is rapidly filled with oil, the fill-up time is shortened and the time lag is reduced. will disappear.

[0047] Therefore, check valves 41 and 4 are installed in flow sensing valves 38 and 39. By incorporating 2, the clutch is operated by pressure-regulated oil, so forward and backward movement is possible. Sufficient modulation can be performed during switching and inching. Also, low temperature Even when the oil viscosity is high, the hydraulic pressure is maintained at the set pressure. Sufficient modulation can be performed during gear changes, etc.

[0048] It should be noted that the present invention is not limited to the above-mentioned embodiments, but may be modified within the scope of the present invention. Of course, many modifications and changes may be made to the embodiments described.

[0049]

[Effect of the idea]

As is clear from the above explanation, according to the present invention, there is By incorporating a check valve, the clutch is operated using regulated oil. Therefore, sufficient modulation can be performed when switching forward or backward or when inching. . In addition, even when the oil viscosity is high at low temperatures, the oil pressure is maintained at the set pressure. This makes it possible to provide sufficient modulation during gear shifting, etc. effective.

[Brief explanation of drawings]

FIG. 1-A is a fluid pressure control circuit diagram of a transmission showing an embodiment of the present invention.

FIG. 1-B is a fluid pressure control circuit diagram of a transmission showing an embodiment of the present invention.

FIG. 2 is a diagram of a modulated waveform obtained according to the present invention.

FIG. 3 is a conventional modulated waveform diagram.

FIG. 4-A is a fluid pressure control circuit diagram of a conventional transmission.

FIG. 4-B is a fluid pressure control circuit diagram of a conventional transmission.

[Explanation of symbols]

31 Forward clutch 32 Reverse clutch 33, 34, 35 Speed stage clutch 36,37 Road piston 38,39 Flow sensing valve 41,42 Check valve

Claims (1)

[Scope of utility model registration request] 1. In a fluid pressure control circuit of a transmission for supplying fluid to a speed clutch and a forward/reverse clutch of a hydraulic drive shaft to operate the clutches, the clutch fluid pressure is gradually increased when the clutches are engaged. A transmission comprising a load piston for raising the load piston and a flow sensing valve for actuating the load piston, and a check valve for regulating fluid pressure to the load piston is provided in the flow sensing valve. Fluid pressure control circuit.