JPS5918189Y2 - transmission - Google Patents

Description

[Detailed description of the invention] The invention provides a relief valve that is opened by the pressure increase in the flow path on the upstream side when a control valve for the hydraulic variable speed drive section opens, and a single-acting cylinder that closes the relief valve. The present invention relates to a transmission device that communicates with the flow path on the upper side of the valve via a throttle valve so as to be activated by a pressure increase accompanying the opening of the valve.

According to the above transmission, in the initial stage of the opening operation of the control valve, the IJ
Pressure oil can be gradually supplied to the transmission drive part while gradually reducing the IJ-flow amount, and as a result, the startup characteristics of the pressure oil supply to the drive part can be maintained at a constant ratio, making starting extremely smooth. can be made to do so.

However, this configuration has the drawback of reducing the smoothness of gear shifting.

In other words, if pressure oil is squeezed and supplied to the transmission drive part every time the vehicle changes gears while the vehicle body is experiencing running inertia, the shifting time will be unnecessarily long and speed changes will occur during that time, making it impossible to perform gear shifts smoothly. Met.

In view of the above-mentioned circumstances, the present invention aims to eliminate the above-mentioned drawbacks through extremely simple structural improvements. The throttle valve is configured to act as a throttle only when the operating tool is switched from the neutral position to the first speed operating position.

In other words, the throttle valve is operated to throttle only when starting in the first gear, which requires throttle supply of pressure oil, and during other gear changes, the operation of the speed change drive unit does not take unnecessary time. It is now possible to not only start but also shift gears smoothly.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

A swivel base 4 is attached to a vehicle body 2 equipped with an all-wheel drive type traveling device 1 via a rotary joint 3, and an engine 5, a hydraulic pump 6 connected thereto, and a control section 7 are attached to the swivel base 4.
In addition to being equipped with a backhoe device 8 for excavation work, the work vehicle is a swing type work vehicle.

To configure the transmission device 9 for the traveling device 1, a hydraulic motor 11 which is operated in forward and reverse directions and stopped by a control valve 10 provided on the swivel table 4 is connected to an input shaft 12, and the input shaft 12 and a transmission shaft are connected to each other. An output shaft 14 for each shaft 13, 13 is installed in a case 15 attached to the vehicle body 2, and four sets of gear-type transmission mechanisms 16 are provided that are always engaged with both shafts 12, 14, and gears 16 a...・Input shaft 1
2, the gears 16b... are loosely fitted to the output shaft 14 so as to freely rotate relative to each other, and the output side gears 16b are selectively integrated with the output shaft 14 by hydraulic pressure. ... with the gear 16b... and the output shaft 1
4, and a hydraulic pump 18 connected thereto is connected to the input shaft 12 using the transmission case 15 as a hydraulic oil tank, and the transmission oil passage of the pump 18 is connected to the transmission drive unit 17... A gear shift operating valve 19 is interposed to sequentially operate the motor 11, and the valve 10 controls the motor 11, and the valve 19 controls the transmission mechanism 16, so that four forward and forward gear shifts can be performed. be.

The speed change operation valve 19 includes a push/pull or rotation type control valve 20 that sequentially operates the speed change drive section 17 from a state in which the pump 18 and the tank port (a) are communicated with each other, and a control valve 20 of a push/pull or rotary operation type, and the speed change drive section. It consists of a modulation valve 21 that changes the pressure oil supply characteristics to 17,
To configure the modulation valve 21, as shown in FIG. 3, a relief valve 22, which is opened by the pressure increase caused by the opening of the control valve 20, is connected to a flow path A connected to the pump port b). , a single acting cylinder 24 for closing this relief valve 22 via a spring 23
is provided with its pressure receiving area set to be larger than the pressure receiving area of the relief valve body, and a flow path B that operates the cylinder 24 by the pressure increase in the flow path A is connected to the flow path A. , a throttle valve 26 is provided in the flow path B, which throttles and supplies pressure oil to the cylinder 24 when the pressure in the flow path A increases.

As shown in FIG. 3, the throttle valve 26 is configured such that a valve body 28 is provided with respect to the throttle valve seat 27 so as to be able to change its position in the flow path direction, and the valve body 28 is biased in the throttle release direction. and a locking piece 30 is attached to the valve body 28, and the locking piece 3 is attached to the push/pull actuator 31 of the control valve 20 via a link mechanism 34.
0, and both engagement pieces 30 are connected to each other.
．． 32 to the operating tool 3 with respect to the operating tool 31.
The throttle valve 26 acts only in the range where the gear shifter 3 is switched from the neutral position N to the first gear operating position ■, and in the second to fourth operating positions II, III, and IV, the throttle valve 26 acts by the biasing force of the spring 29. The valve 20 is set to release the throttle and is controlled by the operating tool 33.
When the valve is opened to the first operation position (3), the pump 18 and the first variable speed drive unit 17 are communicated with each other at the initial stage of opening, and a portion of the pressure oil is relieved to the port C through the relief valve 22. At the same time, pressurized oil is throttled and supplied to the cylinder 24 through the throttle valve 26, and the relief valve 22 is gradually closed due to the difference in pressure receiving area, and the rising operation characteristics of the pressurized oil supply are made constant, thereby smoothly moving the vehicle body 2. When the engine starts moving and the valve 20 is operated for gear change, the cylinder 24 rapidly reaches the end at the time of the shift, the pressure oil supply to the operating part 17 is released, and the throttling action of the throttle valve 26 is released. However, the next gear shift actuating section 17 immediately enters the operating state in the absence of pressure oil relief, that is, the gear shift is configured to be performed smoothly without unnecessary shift time.

Note that d is a leak port.

The throttle valve 26 is provided with a regulating device that acts on the valve body 28 to urge the valve body 28 in the throttle direction and maintain a constant throttle state in the free state, and the restriction device acts on the valve body 28 and is not used for operations beyond the second gear shift. At this time, the valve body 28 may be configured to forcibly move in the throttle release direction, or the spring 29 may be omitted and the valve body 28 and the operating tool 33 may be directly linked, that is, the structure of the throttle valve 26 may be , and operating tool 3
It is possible to make various modifications to the linkage structure for 3.

[Brief explanation of the drawing]

The drawings show an embodiment of the transmission according to the present invention, in which FIG. 1 is an overall side view of a working vehicle, FIG. 2 is a schematic explanatory diagram of the transmission,
FIG. 3 is a cutaway side view of essential parts of the speed change operation valve, and FIG. 4 is a hydraulic system diagram.

Claims (1)

[Scope of utility model registration request] Control valve 20 for hydraulic variable speed drive unit 17...
A relief valve 22 is provided which is opened by the pressure increase in the flow path on the upper side when the valve is opened, and a single acting cylinder 24 that closes the relief valve 22 is operated by the pressure increase when the valve 200 is opened. The transmission is connected to a flow path through a throttle valve 26, and the operating tool 33 of the valve 20 and the throttle valve 26 are linked to each other, so that the operating tool 33 changes from a neutral position N to a first speed operating position I. A transmission characterized in that the throttle valve 26 is configured to perform a throttling action only when switching is performed.