JPH0718458B2 - Hydraulic clutch pressure adjustment structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a first pressure increase until the pressure on the secondary side reaches a first set pressure from zero pressure in a pressure oil supply system to a hydraulic clutch for shifting. The section, the second boosting section from the first setting pressure to a second setting pressure higher than the first setting pressure, and the third boosting section exceeding the second setting pressure are respectively used for the shifting. Pressure adjustment of a hydraulic clutch provided with a pressure adjusting mechanism for switching the pressure increasing speed of the hydraulic clutch and making the pressure increasing speed in the second pressure increasing section smaller than the pressure increasing speed in the first pressure increasing section and the third pressure increasing section. Regarding the structure.

[Conventional technology]

Conventionally, a pressure adjusting mechanism includes a low-pass valve that closes when a pilot pressure on the secondary side exceeds a first set value and a pilot pressure on the secondary side that is the first pilot pressure in the pressure oil supply system to the shift hydraulic clutch. It is composed of a high-pass valve that opens when the second set value is higher than the set value, and these valves and throttle mechanism are connected in parallel. JP-A-61-102828).

[Problems to be solved by the invention]

In this case, since the closing pilot pressure of the low-pass valve is constant, it is desirable to set the initial clutch engagement pressure (meet point) low in a low speed shift state in which the axial torque is large and the inertial force of the traveling vehicle body is small. Nevertheless, the first set pressure is increased all the way to cause a large shift shock, and because the shaft torque is small and the inertial force of the traveling vehicle body is large, the shift shock is relatively small in the high speed shift state, and the initial engagement of the clutch is reduced. Although it is desirable to set the relieving pressure (meat point) high, after the pressure is raised to the first set pressure, it is gradually raised by the throttle mechanism to reach the initial joint pressure. There was a problem that it took time to reach.

It is an object of the present invention to provide a system in which a new mechanism is added to a pressure oil supply system for a hydraulic clutch to obtain a boosting characteristic suitable for a gear shift state.

[Means for solving problems]

A characteristic configuration according to the present invention is that an accumulator mechanism capable of changing a capacity is provided in series in the pressure oil supply system in series with the pressure adjusting mechanism, and that the traveling gear shift position becomes lower, the accumulator mechanism of the accumulator mechanism becomes smaller. A switching means for increasing the capacity is provided, and the operation and effect are as follows.

[Action]

That is, the pressure increase by only the pressure adjusting mechanism is as follows. Until the first set pressure is reached, the pressure is increased at the first boost section, and until the second set pressure is exceeded after exceeding the first set pressure.
It is possible to perform the boosting at a boosting rate lower than the boosting rate in the first boosting section, and when the second set value is exceeded, the boosting rate can be set to be higher than the boosting rate in the second boosting section.

Based on the boosting characteristic as described above, the boosting characteristic when the accumulator mechanism is added to the pressure adjusting mechanism is as follows.

When the capacity of the accumulator mechanism is increased, as shown in the diagram (a) of FIG. 3, the time (Ta) until the pressure is increased to the first set pressure (P ₁ ) can be lengthened, and conversely, the accumulator mechanism can be increased. When the capacity of the mechanism (26) is reduced, the time (Tb) until the pressure is increased to the first set pressure (P ₁ ) can be shortened as shown in the diagram (b). Therefore, as in the characteristic configuration, by changing the capacity, even if the initial connecting pressure (P ₀ ) is constant, the time until the initial connecting pressure (P ₀ ) is reached in the low speed shift state is delayed. As a result, the shift shock can be alleviated, and the initial joint pressure (P ₀ ) can be obtained in a short time in the high speed shift state.

〔The invention's effect〕

Therefore, it is possible to obtain the boosting characteristic suitable for the shift state, and it is possible to make a finer change than that in which the boosting characteristic is determined only by the pressure adjusting mechanism.

Particularly, in the case of the present invention, the pressure rising speed up to the first set pressure can be varied by the accumulator mechanism so that the pressure up to the initial connection pressure can be reached in the shortest time with little shift shock. The feature is that the boosting speed is changed, and further, the boosting speed is changed in correspondence with the gear shift position, and the boosting speed is controlled more finely.

However, if only the configuration in which the boosting characteristic up to the first set pressure (P ₁ ) can be changed according to the traveling speed change state is captured, it is disclosed in Japanese Examined Patent Publication No. 61-295131 as having the same effect. However, since this one has a characteristic structure for switching the throttle mechanism to one having different throttle characteristics, as shown in the diagram (c) of FIG. 3, the first set pressure (P ₁ ) is exceeded. tend to take too long to throttling effect is worked up to the clutch actuation pressure (P ₃₎ Te, but in the case of the present invention carried out in the accumulator mechanism (26), as in the case of the diagram (b), Since the throttling effect is suppressed after the pressure exceeds the first set pressure (P ₁ ), it is possible to shorten the time for increasing the pressure to the clutch operating pressure (P ₃ ) and obtain light operability.

〔Example〕

FIG. 1 shows a transmission structure in a mission case (M) equipped on a tractor, and includes a transmission shaft (1) connected to an engine (E) and a traveling first transmission shaft (2). A synchromesh type main gear transmission (H ₁ ) capable of switching between stages is provided, and a friction plate type hydraulic clutch (C) is provided between the first transmission shaft (2) and the traveling second transmission shaft (3). A synchromesh type forward / reverse gear transmission (H ₂ ) that changes the output of the second transmission shaft (3) between forward and reverse rotations, a cyclomesh type auxiliary gear transmission (H ₃ ) that can switch the output from the high and low stages, and ,
A gear interlocking mechanism (H ₄ ) for outputting the output from that to the front wheels is provided respectively, and the output of the auxiliary gear transmission (H ₃ ) is provided to the differential mechanism (4A) of the rear wheels (4) and the front wheels ( It is configured to be transmitted to the differential mechanism (5A) of 5).

It is provided in a synchromesh gear transmission (7) that changes the power of the input shaft (1) and transmits the power to the power take-off transmission shaft (6), and between the transmission shaft (6) and the power take-off shaft (8). Further, a one-way clutch (9) is provided so that the power take-off shaft (8) can be shifted.

Next, a gear shift operation structure for the traveling transmission system will be described in detail with reference to FIGS. 1 and 2.

That is, the main gear transmission (H _1), alternatively the two main gear transmission shifter is actuated (10A), two operating hydraulic cylinder interlockingly connected to each of (10B) (11A) , (1
1B), and an auxiliary hydraulic transmission (H ₃ ) is provided with an operating hydraulic cylinder (13) in which an auxiliary gear transmission shifter (12) is interlockingly connected.

Also, the pistons of the two operating hydraulic cylinders (11A) and (11B) for the main gear transmission (H ₁ ) and the operating hydraulic cylinders (13) for the auxiliary gear transmission (H ₃ ) are slidably spooled. The three three-position switching valves (S ₁ ), (S ₂ ), and (S ₃ ) are configured so that they can be used as both.

Supply of pressure oil to the operating hydraulic cylinders (11A), (11B), (13), and the three-position switching valve (S ₁ ),
The pressure oil is supplied to (S ₂ ) and (S ₃ ) by the main control valve (V ₁ )
Is operated by operating a rotary 9-position (N, F _{1 to} F ₈ ) switching valve, and the pressure oil is supplied to the 9-position switching valve (V ₁ ) from the hydraulic pump (P). ) Via.

The transmission hydraulic clutch (C) is driven by the hydraulic pressure supplied from the pressure reducing valve (15) through a pressure adjusting mechanism (16), and the pressure control valve mechanism (16) and the hydraulic clutch (C). ) And a clutch engagement state in which the pressure oil from the pressure control valve mechanism (16) is supplied to the clutch (C),
Four pilot pressure-operated two-position switching valves (17A), (17A), () that can be selectively switched between a clutch disengaged state in which the pressure oil in the clutch (C) is returned to the tank (T) 17
B), (17C), (17D) are connected in series, and one of these is a pilot pressure operated 2-position switching valve (17
A) is an auxiliary control valve (a) which is operated in conjunction with a manual operation lever (18) for operating the forward / reverse gear transmission (H ₂ ) and which is connected in parallel with the main control valve (V ₁ ). Operated by pressure oil supplied from V ₂ ), the remaining three pilot pressure operated 2-position switching types (17A), (17C), (17D) are
Each of them is operated by pressure oil supplied from the three-position switching valves (S ₁ ), (S ₂ ), (S ₃ ), so that the main gear transmission (H ₁ ) and the forward / reverse gear transmission (H ₂ ) And the auxiliary gear transmission (H ₃ ) are all in the transmission state, the four pilot pressure operated two-position switching valves (17A), (17B),
When all of (17C) and (17D) are switched to the communicating state, the clutch is switched to the engaged state, and the clutch (C) is automatically switched according to the gear shift operation.

However, the two hydraulic cylinders of the main gear transmission (H ₁ ) (11
When one of A) and (11B) is operated to the shift side,
The other hydraulic cylinder is configured to be operated and held by a pressure oil in a neutral position. Further, the second sub gear transmission (H ₄ ) is provided with a shifter which can be operated by a shift lever. Further, the transmission (7) for the power take-off shaft (8) is configured to be operated manually.

In the figure, (N) and (F ₁ ) to (F ₃ ) respectively indicate the operating position of the main control valve (V ₁ ), and (F) and (R)
Indicates the operation position of the auxiliary control valve (V ₂ ), and (H) and (L) indicate the operation position of the auxiliary gear transmission three-position switching valve (S ₃ ).

As shown in FIG. 2, a disc brake mechanism (14) is provided on the second transmission shaft (3), and a brake cylinder (19) is provided as a hydraulic operating mechanism for the disc brake mechanism (14). The piston (19A) of (19) is linked to the operation member (14A) of the disc brake mechanism (14), and this brake cylinder (19)
Is connected to the oil passage on the upstream side of the main control valve (V ₁ ). And the piston (19A) of this brake cylinder (19)
Is urged by a spring into a brake operating state, and when the engine (E) is turned on and pressure oil is supplied, it moves to the brake disengagement side. That is, it is possible to construct a parking brake structure in which the brake is automatically applied when the engine (E) is stopped, and since the hydraulic clutch type is also a speed change mechanism, it is self-shifting at a shift position like other mechanical speed change mechanisms. It is possible to compensate for the fact that the lock function cannot be expected.

As shown in FIGS. 1 and 2, the pressure adjusting mechanism (1
6), in the first step-up section up to the pilot pressure of the secondary side becomes the first set pressure (P ₁₎ in the open state, the pilot pressure of the secondary side first set pressure (P ₁₎ above Then, the low-pass valve (20) that closes and the high-pass valve (21) that opens in the third boosting section where the pilot pressure on the secondary side is higher than the first set pressure (P ₁ ) and higher than the second set pressure (P ₂ ). ), A throttle mechanism (22) consisting of these valves (20) (21) and an orifice in which the pilot pressure acts in the second boosting section from the first set pressure (P ₁ ) to the second set pressure (P ₂ ). Are connected in parallel.

On the other hand, the first accumulator (23) and the second accumulator (24) are provided in the pressure oil supply passage between the hydraulic clutch (C) and the switching valve (17), and the pressure oil to the second accumulator (24) is provided. in the supply path, it is the auxiliary gear speed change device for three-position switching valve (S ₃₎ switch valve in conjunction with the spool switching switched accumulator mechanism (25) is provided. The accumulator mechanism switching valve (25) is in an ON state in which pressure oil is supplied to the second accumulator (24) when the auxiliary gear transmission 3-position switching valve (S ₃ ) is in the low speed position (L). , The auxiliary gear transmission 3 position switching valve (S ₃ ) is neutral
When in the high speed position (H), the second accumulator (2
It can be switched to the OFF state where 4) communicates with the tank (T). Therefore, the pressure oil supply to the second accumulator (24) can be automatically switched according to the traveling speed change state, and the accumulator mechanism (2 consisting of the first accumulator (23) and the second accumulator (24) in the low speed state.
The capacity of 6) can be increased, and the accumulator mechanism switching valve (25) is called switching means therefor.

[Other Embodiments] a As the accumulator mechanism (26), a single accumulator whose capacity can be varied may be used.
A plurality of accumulators having different capacities may be provided and the target (accumulator) to which the pressure oil is supplied may be switched according to the traveling speed change state. In any case, the accumulator may be used.

B said switching means (25) as may be an electromagnetic valve may a configuration based on a detection result of the sensor for detecting the shift position of the auxiliary gear speed change device for three-position switching valve (S ₃₎ switch the solenoid valve take, It is not limited to the switching valve.

(C) The pressure adjusting structure described above can be applied to any working machine, working vehicle, and general vehicle as long as it has a hydraulic clutch type transmission.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

The drawings show an embodiment of the pressure adjusting structure of a hydraulic clutch according to the present invention, FIG. 1 is a configuration diagram showing a transmission structure of an agricultural tractor, FIG. 2 is a pressure oil supply system diagram for a speed changing hydraulic clutch,
FIG. 3 is a graph showing the boosting characteristics when the capacity of the accumulator mechanism is changed and when the orifice is used. (16) …… Pressure adjusting mechanism, (20) …… Low-pass valve,
(21) …… High-pass valve, (22) …… Throttle mechanism, (2
5) …… Switching means, (26) …… Accumulator mechanism,
(C) …… hydraulic clutch, (P ₁ ) …… first set value,
(P ₂ ) …… Second set value.

Claims (3)

[Claims] 1. A first boosting section from a pressure on the secondary side to a first set pressure from zero pressure in a pressure oil supply system to a hydraulic clutch (C) for shifting, and from the first set pressure. The second pressure increasing section from the first setting pressure to a second setting pressure higher than the first setting pressure and the third pressure increasing section exceeding the second setting pressure respectively increase the pressure increasing speed of the shift hydraulic clutch (C). A pressure adjusting structure for a hydraulic clutch provided with a pressure adjusting mechanism (16) for switching the pressure increasing rate in the second pressure increasing section to be smaller than the pressure increasing rate in the first pressure increasing section and the third pressure increasing section. In the pressure oil supply system, an accumulator mechanism (26) whose capacity can be changed is provided in series with the pressure adjusting mechanism (16), and the accumulator mechanism ( 26) Switching to increase the capacity Pressure adjustment structure of a hydraulic clutch which is provided with a stage (25). 2. The pressure adjusting structure for a hydraulic clutch according to claim 1, wherein the accumulator mechanism (26) comprises a plurality of accumulators. 3. A pressure adjusting structure for a hydraulic clutch according to claim 1, wherein the accumulator mechanism (26) is composed of a single variable displacement accumulator.