JPH02209668A - Speed change gear - Google Patents

Abstract

PURPOSE:To increase pressure along a desired characteristic even if a sudden pressure increase is caused on the hydraulic clutch side by forming a pressure governor mechanism of a pressure reducing valve type and forming a pilot oil path for increasing the spring pressure with an increase in pressure of an intermediate oil path. CONSTITUTION:As a pressure governor mechanism F is formed as a pressure reducing valve type, if the pressure of a hydraulic clutch B is suddenly increased in a short time, a valve element 24 is temporarily blocked by a plunger 25 so that under the condition of interrupting the pressure from a hydraulic pump 7, the pressure is let escape from the intermediate oil path 8a side to the tank side so as to decrease the cllutch pressure to a desired pressure in a short tine. Further, with the increase in pressure on the intermediate oil path 8a, the spring pressure is increased, so that pressure is regulated without any influence on a system attached to the hydraulic pump 7.

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 significantly, the relief valve will reduce this increased pressure 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

The purpose of the present invention is to prevent the entire hydraulic system from being adversely affected even if the clutch pressure is increased from a relatively low pressure, and to maintain desired characteristics even if a sudden pressure increase occurs on the hydraulic clutch side. The object of the present invention is to rationally configure a transmission that can increase the pressure at the same time.

[Means to solve the problem]

A feature of the present invention is that, as described above, in a transmission equipped with a pressure regulating mechanism for setting a pressure increase characteristic, the pressure regulating mechanism is interposed in an oil passage for operating the hydraulic clutch, and one of the oil passages is As the pressure in the intermediate oil passage on the hydraulic clutch side increases to more than the spring pressure, the intermediate oil passage is configured as a pressure reducing valve type to release the pressure in the intermediate oil passage to the tank side, and as the pressure in the intermediate oil passage increases, the A pilot oil passage is formed to increase the spring pressure, and its functions 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).

〔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 has been rationally constructed that can increase the pressure in accordance with desired characteristics.

〔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 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 (^) is composed of two synchromesh type gear transmission mechanisms, and is capable of shifting into four speeds, and the forward/reverse switching device (C) and the sub-transmission (D) are both synchronized. The main transmission (^) has two hydraulic cylinders (T+).

(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), (r
A rotary type speed change control valve (10) for controlling the switching valves (T3) and a pilot oil passage (11) for obtaining pilot pressure for operating the switching valve (9) are branched.

Note that the hydraulic cylinder ('r+)+ (r,), (
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 ( By changing the biloft pressure relative to 9), the hydraulic clutch (B) is operated on and off as described above.

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

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 (^), the mid case (14) houses the hydraulic clutch (B) and the forward/reverse switching mechanism (C), and the rear case (15) houses the hydraulic clutch (B) and forward/reverse switching mechanism (C). ) 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 sub-transmission shifter (18) extend to this opening. ), (17), (19)
The three hydraulic cylinders (T +
).

(Tz) and (T3) are provided, and these hydraulic cylinders (
T1) (Tz), (T3) piston loft (21)
, (21) , (21) end bracket (2
1a), (21a), (21a) and the brackets (17a), (17a), (19a) at the ends of the shift lofts (17), (17), (19)
) are connected via pins (P), (P), and (P).

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

The pressure regulating mechanism (F) is provided on the outer surface of the lid (20).
, a switching valve (9), and a speed change control valve (10), and when configuring a so-called manual speed transmission type transmission system in which a speed change operation is not performed by hydraulic pressure, an opening (14a) is formed. A mid-sized case is now used.

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 the hydraulic clutch (B) via the 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 loft (36) is housed in the case (37), and the pressure chamber (37a) and the second oil chamber (29a)
and the hydraulic cylinder (T, ) for the sub-transmission.
The oil passage (38) for operating the accumulator (G) toward the high speed side 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, when the pressure of the hydraulic clutch (B) 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]

The present invention can be constructed in addition to the embodiments described above, for example, without an accumulator, and the pressure regulating mechanism can also be manufactured in a structure other than that described above.

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, (F) ...Pressure regulation 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 transmission device in which a pilot oil passage (32) is formed for controlling the transmission.