JPH02209670A - Speed change gear - Google Patents

Abstract

PURPOSE:To prevent a speed change shock even if a sudden pressure increase is caused on the hydraulic clutch side without bad influence upon the whole hydraulic system even if the clutch pressure is increased by interposing a pressure regulating mechanism of a pressure reducing valve type in an oil path of a hydraulic clutch and providing an accumulator branching off a pilot oil path for increasing the spring pressure. CONSTITUTION:A pressure regulating mechanism F is interposed in an oil path 8 for operating a hydraulic clutch B. The mechanism is formed like a pressure reducing valve constructed so that as a pressure spring of an intermediate oil path 8a on the hydraulic clutch B side of the oil path 6 is increased more than the spring pressure, the pressure of the intermediate oil path 8a is let escape to the tank side. A pilot oil path 32 for increasing the spring pressure with an increase in pressure of the intermediate oil path 8a is formed. Further, an accumulator G for increasing and decreasing the capacity corresponding to a preset speed change step is provided branching off the pilot oil pressure 32.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention includes a hydraulic clutch for speed change interposed in a traveling transmission system, and a pressure regulating mechanism that sets a pressure increase characteristic when the hydraulic clutch is engaged. More specifically, a transmission comprising a pressure regulating mechanism that feeds back clutch pressure when a hydraulic clutch is operated to the input side and increases the hydraulic clutch pressure with predetermined characteristics. It is related to.

[Conventional technology]

Conventionally, as a technique for adjusting the clutch pressure as described above, there is a technique shown in Japanese Utility Model Application Publication No. 57-72334, in which a relief valve is installed in the oil passage that supplies pressure oil to the hydraulic clutch. In addition to being provided in a branched manner, a pilot oil passage is provided for increasing the spring pressure of the relief valve as the pressure in this oil passage increases.

[Problem to be solved by the invention]

Considering the clutch pressure when engaging the hydraulic clutch, this type of hydraulic clutch has a friction plate and is configured as a friction type, so when engaging the hydraulic clutch, the pressure is relatively low. From the viewpoint of reducing shock, it is desirable to appropriately extend the duration of the half-clutch state in a wide pressure range from low clutch pressure to high clutch pressure.

However, since the pressure regulating mechanism in the above cited example uses a relief valve, when attempting to increase the pressure while maintaining the hydraulic clutch in a half-clutch state, the relief pressure is low at the beginning of the pressure increase operation, so a large amount of pressure is required. Hydraulic oil will be discharged via relief pressure, which may temporarily reduce the pressure of the entire hydraulic system. Also, when the friction plates come into contact with each other, the clutch pressure may decrease for a short period of time. (If the pressure increases, this increased pressure will be reduced by the relief valve under the pressure from the hydraulic pump.
Not only does it take time to get the clutch pressure to match the desired pressure, but this sudden increase in pressure also acts on the spring pressure of the relief valve, so the pressure regulating operation may not follow the desired pressure increase characteristics, so this is an improvement. There is room for.

In addition, in the case of a hydraulic clutch for gear shifting, it is desirable to change the pressure increase characteristic of the hydraulic clutch in accordance with the gear to be selected when the clutch is engaged, that is, the gear is set at a relatively high speed position. In this case, high-speed, low-torque rotational power is transmitted to a transmission system equipped with a hydraulic clutch, so even if the pressure of the hydraulic clutch is increased in a short period of time, shock is unlikely to occur. When the hydraulic clutch is set to , low-speed, high-torque rotational power is transmitted to the transmission system equipped with the hydraulic clutch, so if the pressure of the hydraulic clutch is increased in a short period of time, This is because it is conceivable that F7 failure may occur.

An object of the present invention is to prevent the entire hydraulic system from being adversely affected even when the clutch pressure is increased from a relatively low pressure, and to
The object of the present invention is to rationally configure a transmission device that is unlikely to cause a shock, regardless of the set gear stage, even if a sudden pressure increase occurs on the side of a hydraulic clutch.

[Means to solve the problem]

A feature of the present invention is that in a transmission equipped with a pressure regulating mechanism for setting pressure increase characteristics configured as described above, the pressure regulating mechanism is interposed in an oil passage for operating the hydraulic clutch, and
When the pressure in the intermediate oil passage on the hydraulic clutch side of this oil passage increases to more than the spring pressure, the intermediate oil passage is configured as a pressure reducing valve type that releases the pressure in the intermediate oil passage to the tank side. A pilot oil passage is formed to increase the spring pressure as the pressure increases, and an akinimulator whose capacity is increased or decreased in accordance with the gear position to be set is provided branching off from this pilot oil passage. The point is that it is made up of
Its action and effects are as follows.

[For production]

If the above characteristics are configured as shown in FIGS. 1 and 2, for example, the pressure regulating mechanism (F) is a pressure reducing valve type, so the spring pressure is set low to obtain a low pressure at the beginning of the pressure regulating operation. However, if the clutch pressure increases significantly in a short period of time for some reason, the pressure from the hydraulic pump (7) is cut off. Since the pressure is released from the intermediate oil passage (8a) side to the tank side, it is possible to reduce the clutch pressure to the desired pressure in a short time, and moreover, the pressure on the intermediate oil passage (8a) side can be reduced to the desired pressure. Since the spring pressure is increased as the pressure increases, the pressure can be adjusted without being affected by the system attached to the hydraulic pump (7).

Further, in the present invention, the akinimulator (G) whose capacity is increased or decreased in accordance with the gear position is connected to the pilot oil path (32
), even if pressure fluctuations occur in the intermediate oil passage (8a), the pressure can be increased smoothly by the buffering effect, and the time required for pressure increase can be adjusted in accordance with the gear position. Become.

Incidentally, the change in time required for this pressure increase is expressed as shown in FIG.

〔Effect of the invention〕

Therefore, even if the clutch pressure is increased from a relatively low pressure, there will be no adverse effect on the entire hydraulic system.
Even if a sudden pressure increase occurs on the hydraulic clutch side,
A transmission device that does not easily cause shock regardless of the set gear stage has been rationally constructed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

As shown in Fig. 4, power from the engine (1) is transmitted via a multi-disc main clutch (2) to a main transmission (A), a multi-disc hydraulic clutch (B), and a forward/reverse switching device ( C), the auxiliary transmission (D), and the super reduction gear (E), and transmits the shifting power to the front and rear wheels (3).

(4) A travel transmission system is formed to transmit the power to the respective differentials (3a) and (4a), and the power from the main clutch (2) is transmitted to the external power output shaft (5) via the transmission mechanism (5).
6), a working transmission system is formed to transmit the information to the drive system of the four-wheel drive agricultural tractor.

The main transmission (A) is composed of two synchromesh type gear transmission mechanisms, and is capable of shifting into four stages. The main transmission (^) has two hydraulic cylinders (TI).

(T2), the auxiliary transmission (D) is a single hydraulic cylinder (
) to change gears, and forward/reverse switching device (C).
) is configured to perform a manual speed change operation, and furthermore, in this agricultural tractor, when these three types of speed change operations are performed, the hydraulic clutch (B) is disengaged at the start of the speed change operation, and the speed change operation is performed. A hydraulic control system is provided for shifting the gear without disengaging the main clutch (2) by engaging the hydraulic clutch (B) at the time of completion.

That is, the hydraulic control system is configured as shown in FIG. mechanism(
F), and a pilot pressure-operated switching valve (9), and the three hydraulic cylinders (TI), (T
A rotary type speed change control valve (10) for controlling Z) and (Tel), and a pilot oil passage (11) for obtaining biloft pressure for operating the switching valve (9) are branched.

In addition, the hydraulic cylinders (T,), (Tz), (
T3) and the operating system of the forward/reverse switching device (C) are each linked with an open/close operation type check valve (12). During a gear shift operation, the switching valve ( 9) to operate the hydraulic clutch (B) on and off as described above.

Incidentally, the pressure regulating mechanism (F) suppresses a sudden increase in clutch pressure when the switching valve (9) is turned on,
The clutch pressure is configured to increase with predetermined characteristics.

As shown in Figures 5 to 8, the transmission system of this agricultural tractor is housed in a transmission case that connects a main clutch housing (13), a mid case (14), and a rear case (15). The clutch housing (13) houses the main clutch (2) and the main transmission (A), the mid case (4) houses the hydraulic clutch (B) and the forward/reverse switching mechanism (C), and the rear case ( 15) is equipped with an auxiliary transmission (D) and a super reduction gear (E).

As shown in the figure, the mid case (14) is formed with an opening (14a) that opens the side of the hydraulic clutch (B), and a shifter that connects with two shifters (16), (16) for main gear shifting. The ends of the lofts (17), (17) and the end of the shift loft (19) connected to the auxiliary transmission chic (18) extend to this opening, and these shift rods (17) ), (17), (19)
The three hydraulic cylinders (T +
).

('rz) and (rz) are provided, and these hydraulic cylinders (T + ).

(rz), (h) piston rod (21),
(21), bracket (21a) at the end of (21)
, (21a), (21a) and the shift rod (
The brackets (17a), (17a), and (19a) at the ends of 17), (17), and (19) are connected via pins (P), (P), and (P).

Incidentally, the shift rod (23) connected to the shifter (22) for forward/reverse switching is linked to the operating lever (L).

In addition, on the outer surface side of this lid body (20), the pressure regulating device (F) is installed.
, a switching valve (9), and a speed change control valve (10), and the speed change operation is not performed by hydraulic pressure.
When configuring a variable speed transmission system, the opening (14a)
It is now possible to use a mid-case that does not have a

As shown in FIGS. 1 and 2, the pressure regulating mechanism (F) includes a spool-type valve body (24) and a plunger (24), a part of which is inserted into the inside of the valve body (24). 25), 1st
It is pressed by a spring (26) and has an orifice (
27), a piston (29) actuated by pressure oil from the valve member (28), and a second valve disposed between the piston (29) and the valve body (24). A pilot oil passage system (32) is constructed by housing each spring (30) in a casing (31) and is supplied with pressure oil from a valve body (24).
a) and the first oil chamber (2) in which the valve member (28) is housed.
8a), and communicates with the hydraulic clutch (B) via an intermediate oil passage (8a).

Furthermore, a second oil chamber (29a) houses the piston (29).
) is provided, and this accumulator (G) communicates with the piston part (34) and the spring (3).
5), the contact-south port 7 door (36) is housed in the case (37), and the pressure chamber (37a) and the second oil chamber (29a)
) is in communication with the auxiliary transmission hydraulic cylinder (T3
) to the high speed side, and this
It communicates with the oil chamber (37b) on the side opposite to the pressure chamber of the accumulator (G).

Then, by operating the switching valve (9), the hydraulic clutch (
When the supply of pressure oil to B) is started, the plunger (
25) applies pressure in the closing direction to the valve body (24), and at the same time, pressure in the opening direction accompanying the movement of the piston (29) is applied to the valve body (24) via the second spring (30).
As a result, pressure oil is supplied in a state where the respective pressures are balanced.

Note that when the pressure oil is supplied, when the sub-transmission device (D) is set to the low speed side, the piston portion (3
4) is allowed to operate, a sudden pressure increase is suppressed, and when the auxiliary transmission (D) is set to the high speed side, the operation of the piston part (34) is prevented, making comparison The pressure is increased within a short period of time.

Incidentally, this difference in pressure rise is expressed as in the graph of FIG.

Moreover, since this pressure regulating mechanism (F) is configured as a pressure reducing valve type, if the pressure of the hydraulic clutch (8) increases rapidly in a short period of time, the valve is closed by the operation of the plunger (25). When the body (24) is temporarily closed and the hydraulic clutch (B) is further disengaged, the valve member (28)
opens against the biasing force of the first spring (26), and as a result, the hydraulic oil from the second oil chamber (29a) is discharged within a short time.

[Another example]

In addition to the embodiments described above, the present invention may be configured such that the capacity of the accumulator is adjusted in accordance with each gear stage of a multi-stage transmission, and the structure of the pressure regulating mechanism may also be implemented in various ways. .

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the transmission device according to the present invention, FIG. 1 is a hydraulic circuit diagram for shifting, FIG. 2 is a sectional view of the pressure regulating mechanism, etc., FIG. 3 is a graph showing pressure increase characteristics, and FIG. 4 is the diagram of the transmission system,
Figure 5 is a side view of the transmission case, Figure 6 is a perspective view showing the lid, hydraulic cylinder, etc., Figure 7 is a side view of the lid, and Figure 8 is a sectional view showing the mounting position of the lid. It is. (8)...Oil passage, (8a)...Intermediate oil passage, (32)...Pilot oil passage, (B)...
...Hydraulic clutch, (G) ...Accumulator, (F) ...Pressure regulating mechanism.

Claims (1)

[Claims] A transmission device comprising a hydraulic clutch (B) for speed change interposed in a traveling transmission system, and a pressure regulating mechanism (F) for setting a pressure increase characteristic when the hydraulic clutch (B) is engaged, the transmission device comprising: A pressure regulating mechanism (F) is interposed in the oil passage (8) for operating the hydraulic clutch (B), and the pressure in the intermediate oil passage (8a) on the hydraulic clutch side of the oil passage (8) is The intermediate oil passage (8a) is configured as a pressure reducing valve type that releases the pressure to the tank side as the pressure increases above the spring pressure, and increases the spring pressure as the pressure of the intermediate oil passage (8a) increases. A pilot oil passage (32) is formed therein, and an accumulator (G) whose capacity is increased or decreased in accordance with the gear position to be set is formed in this pilot oil passage (32).
).