JPS616028A - Control circuit for hydraulic clutch for running speed shift - Google Patents

Abstract

PURPOSE:To make a loss time short, by disposing, in parallel, a valve which closes when a secondary pressure exceeds a set value, a valve which opens when the secondary pressure is below the set value and an orifice between a hydraulic pump and a speed shift hydraulic clutch. CONSTITUTION:A valve 18 which closes when a secondary pressure exceeds a set value P1, a valve 19 which opens when the secondary pressure is at a set value P2 higher than the above-mentioned set value P1 and an orifice 20 are connected in parallel together between a pump P and a speed shift hydraulic clutch C in a passage upstream of clutch operation control valves T1 through T4. Accordingly, the valve 18 opens when the secondary pressure is below the set value P1 to boost up the pressure up to the initial operating pressure of the hydraulic clutch C in a short time. Both valves 18, 19 close when the secondary pressure is between both set pressures P1, P2, and therefore the pressure is gradually raised by means of the orifice 20 to offer a smooth clutch operating characteristic. Further, when the secondary pressure exceeds the set value P2, the valve 19 opens to rapidly boost up the pressure up to the set pressure value of a valve 15 to give the normal clutch transmission condition.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is structured so that a gradual external pressure mechanism is installed in a pressure oil supply path between a gear shift hydraulic pump and a hydraulic pump to obtain a smooth latch operation. Concerning a Hydraulic Clutch Operation Circuit for Traveling Transmission [Prior Art] Conventionally, an orifice has been connected between a hydraulic pump and a hydraulic clutch for transmission as a gradual external pressure mechanism. Therefore, in this case, as shown in FIG. 5, the external pressure characteristics of the hydraulic clutch were such that the pressure increased from zero pressure at a constant gradient.

[Problem that the invention seeks to solve]

However, since the clutch has a characteristic that it does not start transmitting torque until it reaches a certain pressure (Po),
As shown in the figure, there is a dead time (to) in which the clutch does not engage until the pressure is increased to (Pa).

It is an object of the present invention to provide a clutch that effectively utilizes the orifice while reducing dead time and providing desirable clutch operating characteristics by adding other mechanisms.

[Means for solving problems]

The characteristic configuration according to the present invention includes a pulp that closes when the secondary pressure is above a certain value and a pulp that opens when the secondary side pressure is a certain value higher than the certain value, between the hydraulic pump and the speed change or hydraulic clutch. The effect of connecting the orifice in parallel is as follows.

[For production]

In other words, as shown in Fig. 4, by setting a constant pressure (P1) to the lowest pressure (Po) at which the hydraulic clutch starts operating, and sending pressure oil to the hydraulic clutch through this valve, the hydraulic clutch can be activated in a short time. Working pressure (P1) can be obtained. Moreover, since both valves are closed from the state exceeding the constant pressure (PI) to the constant pressure (Po) t, pressurized oil is supplied through the orifice, and the hydraulic clutch pressure gradually increases. In addition to smooth latch operation, the other valve opens when the pressure exceeds a certain pressure (P), so pressurized oil is supplied through this valve, and the pressure is increased to the predetermined operating pressure in a short time, increasing the hydraulic pressure. The desired clutch state is achieved as a clutch.

Therefore, by adding a mechanism that connects orifices and valves with different operating characteristics in parallel, it is possible to rationally set the valve's operating pressure and effectively utilize the orifice's throttling effect, resulting in smooth operating characteristics with less wasted time. Ta.

〔Effect of the invention〕

In order to obtain the desired operating characteristics of a hydraulic clutch, it is possible to provide an inexpensive device configuration by simply adding a mechanism by adding a valve, without requiring a complex control mechanism using a microcomputer, etc. .

〔Example〕

Figure 2 shows the transmission structure inside the mission case equipped on the TOFUKUTA. Synchronized main gear transmission (U1)
A friction plate type transmission hydraulic clutch ((2) is provided between the first transmission shaft (2) and the second driving transmission shaft (3),
A synchromesh type forward/reverse gear transmission that changes the output of the second transmission shaft (3) in forward and reverse directions. (H3) and a second auxiliary gear transmission (tortoise) that can freely switch the output from the second gear transmission into two high and low stages, and the output of the second auxiliary gear transmission (H6) is transferred to the rear wheel (4). differential mechanism (4A) and front wheel (5) differential mechanism (5A)
It is configured to transmit power to the

A synchromesh type gear transmission (7) is provided that shifts the power of the input shaft (t1) to one stage and transmits it to the power extraction transmission shaft (6), and also includes a synchromesh type gear transmission (7) that shifts the power of the input shaft (t1) to one stage and transmits it to the power extraction transmission shaft (6).
) is provided with a relay transmission shaft (9), so that the speed of the power take-off shaft (8) can be changed.

Next, the gear change operation structure for the one-travel transmission system will be described in detail with reference to FIGS. 1 to 4.

That is, the main gear transmission (H1) is provided with a hydraulic cylinder (IOA) for operating a gear shifter (IOA), which is selectively operated.
OB), and a first auxiliary gear transmission (OB).
Hs), hydraulic cylinder 02-7 for gear shifter operation
The hydraulic clutch (C) is also provided with a hydraulic cylinder +1& for engaging operation.

The main gear shifting hydraulic cylinder (IOA), (IOB
) and the main control valve (v1) for each of the first auxiliary transmission hydraulic cylinders 112, and the auxiliary control valve (v2) for forward and backward transmission, which is equipped to drive the shift fork integrally with the subu μ, are connected to the hydraulic pump field. ) are connected in parallel to
Then, the pistons of each of the hydraulic cylinders Cl0A) are used also as sliding spools, and the pressure from the 3-position switching valves (comprising three of 8ri, (86), and (84), pump fP) is An oil passage for supplying oil to the clutch operation hydraulic cylinder 03 is provided, and a pilot pressure operated switching valve (T1), (T鵞), for opening and closing the oil passage.
When (TI) and (T6) φ pieces are arranged in series,
In addition, the main gear shifting hydraulic cylinder (IOA), (IOE
) and the first auxiliary transmission hydraulic cylinder (sliding valves (Sm), (8 prefectures), (Sm), each consisting of 12 valves, and auxiliary control valves (operated with pressure oil from the V valve). A valve (
T1).

(T), (Ts), (%'') are input only in the transmission state of the main gear transmission (Ht), forward/reverse gear transmission (Ha), and first auxiliary gear transmission (H3). In order to switch to the operating position, the switching operation is automatically performed in conjunction with the gear shifting operation.

However, the two hydraulic cylinders (
When the forces of IOA) and (IOB) are operated toward the shift side, the other hydraulic cylinder is operated and held at the shift neutral position by pressure oil. Further, the second auxiliary gear y-speed device (currently) K is equipped with a shifter that can be freely operated with a speed change lever. Furthermore, the transmission (7) for the power take-off shaft (8) is configured to be manually shifted.

Main and auxiliary control valves (V2), (V!) and clutch actuation control valves (TI), (Tri, (Tsu, (Ta)
) Also, a reducing valve om for the hydraulic clutch +01 is installed on the upstream side of the flow path to ensure that the secondary side pressure is above a certain pressure, and a reducing valve om for the hydraulic clutch +01 is installed on the upstream side of the flow path, and a The interposed reducing valve Q- for the lifting cylinder (11), which opens when the downstream pressure exceeds a certain pressure, and the above-mentioned reducing valve (lI5) actuate the hydraulic clutch (@ and the lifting cylinder (lli), respectively. In addition to controlling the supply of pressure oil set at a pressure, the pressure oil that was conventionally returned to the hydraulic tank is returned to the hydraulic tank using a relief valve, so that it can be used effectively according to the set pressure.Furthermore, Since both bags θ are installed inside the filter 07) placket (17A) attached to the filter 07), it is advantageous in terms of installation space and piping construction.

In the pressure oil path between the reducing valve Q[il and the pilot pressure operated switching valve (T1), there is a valve 11111 that closes when the secondary pressure is above a certain value (P1) and a valve 11111 that closes when the secondary pressure is above a certain value (P1). Constant value (P2) higher than constant value (PI)
The valve (I (to)) that opens at 100°C and the orifice hole are connected in parallel, so that at pressures lower than a certain value (Pi), the pressure oil passes through the pulp haze and the hydraulic clutch +0 is reached in a short time.
The external pressure is applied to the initial operating pressure of 1, and between the constant value (P1) and the constant value (P2), the pressure oil passes through the orifice because both pulps H and ati+ are closed, and the latch characteristic is smooth. The pressure is gradually increased so as to obtain a pressure of , ordinary hydraulic clutch te
l Express the transmission state.

[Another example]

The above embodiments may be applied to agricultural ledger vehicles other than Tofukuta.

[Brief explanation of drawings]

The drawings show an embodiment of the hydraulic clutch operation circuit for traveling speed change according to the present invention, and FIG. 1 is a hydraulic circuit diagram for the hydraulic clutch;
Figure 2 is a configuration diagram of the travel drive system, Figure 3 is a side view showing how the hydraulic pump is installed, Figure 4 is a graph showing the operating pressure characteristics of the hydraulic clutch, and Figure 5 is the operating pressure of a conventional hydraulic clutch. It is a graph showing characteristics. (1~,09)...Pulp, blowing...orifice, (P)...hydraulic pump, (P1),
(Pm)...Constant pressure. Agent Patent Attorney Osamu Kitamura1<

Claims (1)

[Claims] Between the hydraulic pump (P) and the hydraulic clutch for speed change (C), there is a pulp (
18), a valve (19) that opens at a constant value (P_2) where the secondary side pressure is higher than the above-mentioned constant value (P_1), and an orifice (20) are connected in parallel. circuit.