JPH0966749A - Hydraulic circuit structure of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the supporting structure of a filter for a hydrostatic type continuously variable transmission, in a service car equipped with this hydrostatic type continuously variable transmission for traveling use. SOLUTION: A hydraulic block 9 is connected to one side of a traveling transmission case 5, and a hydrostatic type continuously variable transmission 6 for traveling use is connected to an outer side face of this hydraulic block 9. Then, a filter 35 is connected to the hydraulic block 9, and thereby a hydraulic fluid is constituted so as to be supplied to the hydrostatic continuously variable transmission 6 via the filter 35 and an oil passage installed in the hydraulic block 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a hydraulic circuit for a hydrostatic stepless transmission in a work vehicle equipped with a hydrostatic stepless transmission for traveling.

[0002]

2. Description of the Related Art When a hydrostatic continuously variable transmission is provided for traveling, there is generally a leakage of hydraulic oil from the hydrostatic continuously variable transmission. Need to replenish. In this case, the hydraulic oil is supplied to the hydrostatic continuously variable transmission through the filter.

[0003]

In the work vehicle described above, there is room for improvement in terms of simplifying the support structure for the filter. An object of the present invention is to simply configure a filter support structure in a work vehicle equipped with a hydrostatic continuously variable transmission for traveling.

[0004]

[Means for Solving the Problems]

[I] When the hydrostatic continuously variable transmission is equipped for traveling, the hydrostatic continuously variable transmission is provided with a hydraulic block having an oil passage internally connecting the input-side hydraulic pump and the output-side hydraulic motor. There are many cases. Claim 1 by this
According to the characteristics of the above, since the filter is supported by the hydraulic block of the hydrostatic continuously variable transmission, which may be called an existing structure, a dedicated opening for supporting the filter, a connecting seat, etc. are newly added to the mission case. There is no need to install it in.

Since the hydraulic block is often in the form of a flat plate having a large thickness, when the filter is connected, the hydraulic block does not need to be mechanically machined to connect the filter.
The filter can be connected to the hydraulic block with relative ease.
Since the filter connected to the hydraulic block and the hydrostatic stepless transmission are connected by the oil passage built in the hydraulic block, the pipes connecting the filter and the hydrostatic stepless transmission are connected to the hydraulic block. There is no need to provide it outside of.

The hydrostatic continuously variable transmission generally has relatively large vibration. Therefore, if the filter is connected to the hydraulic block to which the hydrostatic stepless transmission is directly connected as in the feature of claim 1, the total weight and volume of the hydrostatic stepless transmission and the hydraulic block increase. Therefore, the book effect suppresses the vibration of the hydrostatic continuously variable transmission.

[II] According to the characteristics of claim 2, as in the case of claim 1, the "action" described in the above [I] is provided, and in addition to this, the following "action" is provided. ing. In a work vehicle, hydraulic oil from one pump is often branched in parallel to a plurality of supply systems, and the hydraulic oil is supplied from each supply system to each of a plurality of hydraulic devices. There is a case where a hydrostatic continuously variable transmission is connected to one of the plurality of supply systems, and hydraulic oil is supplied to the hydrostatic continuously variable transmission through a filter.

In this case, a normally closed type on-off valve that does not open unless the pressure on the upstream side exceeds a predetermined pressure is provided in the supply system to the hydrostatic stepless transmission, and the upstream side (pump side) of the filter is provided. It may be configured to ensure pressure. Thus, according to the feature of claim 2, since the valve block incorporating the above-mentioned on-off valve is connected to the hydraulic block together with the filter, a dedicated opening for supporting the valve block, a connecting seat, etc. are provided. There is no need to add a new mission case. For the hydraulic block to which the hydrostatic stepless transmission is directly connected, the valve block is connected in addition to the filter, and the total weight and volume of the hydrostatic stepless transmission and the hydraulic block are further increased. The book effect further suppresses the vibration of the hydrostatic continuously variable transmission.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, a lift is provided on a front portion of an airframe supported by a pair of left and right front wheels 1 (uncontrollable steering) and a pair of left and right rear wheels 2 (uncontrollable steering). The mower 3 is movably supported via the arm 36 to constitute a riding lawn mower which is an example of a work vehicle. As shown in FIG. 2 and FIG. 1, the engine 4 is arranged at the rear part of the machine body, the mission case 5 supporting the front wheels 1 is arranged at the front part of the machine body, and the hydrostatic type is provided at the rear side of the body of the mission case 5. The continuously variable transmission 6 is connected. As a result, power from the engine 4 is transmitted to the hydrostatic continuously variable transmission 6 via the transmission shaft 7, and the gears are operated in the hydrostatic continuously variable transmission 6 and the transmission case 5 to be transmitted to the front wheels 1. It The power branched from just before the front wheel 1 is transmitted from the dual one-way clutch 8 to the rear wheel 2 via the transmission shaft 18.

Next, the structure near the mission case 5 will be described. As shown in FIGS. 3 and 4, the hydraulic block 9 of the hydrostatic continuously variable transmission 6 is connected to the rear portion of the body of the transmission case 5, and the rear surface of the hydraulic block 9 is connected to the rear portion of the stationary body. The hydraulic continuously variable transmission 6 and the transmission case 10 to the rear wheel 2 are connected. The power from the engine 4 is transmitted to the input shaft 11 of the hydrostatic continuously variable transmission 6 via the transmission shaft 7 (see FIG. 2), and the hydrostatic continuously variable transmission 6
Power from the output shaft 12 penetrating the hydraulic block 9,
It is transmitted to the differential mechanism 15 of the front wheel 1 via the sub transmission 13 and the pinion shaft 14.

The power of the pinion shaft 14 is transmitted by the transmission gear 16
It is transmitted to the dual one-way clutch 8 in the transmission case 10 via the (to be relatively rotatably fitted to the PTO shaft 24 described later) and the transmission shaft 17, and is transmitted from the output shaft 26 of the dual one-way clutch 8 to the transmission shown in FIG. It is transmitted to the rear wheel 2 via the shaft 18. The auxiliary transmission 13 is of a gear shift type, and a shift gear 19 slidably fitted on the pinion shaft 14 by a spline structure is slidably operated to engage with a high speed gear 20 or a low speed gear 21 to increase or decrease the height. It is possible to shift gears. The power of the input shaft 11 of the hydrostatic continuously variable transmission 6 is transmitted to the transmission gear 22 and the PT.
It is transmitted to the PTO shaft 24 via the O-clutch 23, and the power is transmitted to the mower 3 shown in FIG. 1 via the PTO shaft 24.

As shown in FIG. 4, the hydraulic block 9 is an oil passage connecting a hydraulic pump (not shown) on the input side and a hydraulic motor (not shown) on the output side in the hydrostatic continuously variable transmission 6. (Not shown) is installed inside to isolate the inside of the hydrostatic stepless transmission 6 from the inside of the transmission case 5. As shown in FIG. 5, the lower part of the hydraulic block 9 is extended downward, and the transmission case 10 is connected to this extended portion.
The end of the TO shaft 24 is bearing-supported. In this case, through the opening 9a formed in the hydraulic block 9,
The inside of the transmission case 10 and the inside of the transmission case 5 communicate with each other, and the lubricating oil flows back and forth to each other.
A transmission shaft 17 penetrates and is supported by the island portion 9b of the hydraulic block 9. Further, the transmission case 10 is provided with a switching valve 25 for transmitting and disconnecting the PTO clutch 23.

The dual one-way clutch 8 installed in the transmission case 10 is used when the vehicle is traveling straight (forward and backward).
At the output shaft 2
6 is transmitted, and in this state, the front wheels 1 and the rear wheels 2 are driven to become a four-wheel drive state. Next, when the rear wheel 2 is about to be driven forward or reversely from the ground at a higher speed than the front wheel 1 due to the difference in the turning radius when the vehicle is turning, the power for forward or reverse rotation is cut off in the dual one-way clutch 8. The front wheels 1 are in the two-wheel drive state. Further, the dual one-way clutch 8 can be switched to a four-wheel drive state in which the front wheels 1 and the rear wheels 2 are always driven regardless of whether the vehicle is traveling straight or turning.

Next, the hydraulic circuit structure will be described. As shown in FIG. 9, the hydraulic oil from the pump 27 is transferred to the flow dividing valve 28.
Is supplied to the hydraulic cylinder 29 and the switching valve 30 for swinging the lift arm 36 (see FIG. 1), and to the power steering mechanism 31 of the rear wheel 2 via the flow dividing valve 28. The hydraulic oil discharged from the power steering mechanism 31 is supplied from the oil cooler 32 to the hydrostatic continuously variable transmission 6 via the outer pipe 33, the branch portion 37, the opening / closing valve 34, and the filter 35, and is branched. It is supplied to the switching valve 25 of the PTO clutch 23 via the portion 37 and the outer pipe 38.

As shown in FIGS. 6 and 9, the on-off valve 34 is a normally closed type that does not open until the pressure on the hand side (power steering mechanism 31 side) exceeds a predetermined pressure. 37 and 37 are mounted in one valve block 39. As shown in FIGS. 2, 4, 6, 7, and 8, the valve block 39 is connected to the upper surface of the hydraulic block 9 on the same rear surface of the machine body as the hydrostatic continuously variable transmission 6.
A filter 35 is connected to 9. As a result, the hydraulic oil from the pipe 33 is supplied to the filter 35 via the branch portion 37 of the valve block 39 and the opening / closing valve 34, and the hydraulic oil from the filter 35 passes through the valve block 39 again to the hydraulic block 9. It is supplied to the hydrostatic continuously variable transmission 6 through the oil passage 40 provided therein.

[0016]

According to the first aspect of the invention, in a work vehicle equipped with a hydrostatic continuously variable transmission for traveling, by connecting a filter to the hydrostatic continuously variable transmission to an existing hydraulic block, Since it is not necessary to newly provide an exclusive opening for supporting the filter, a connecting seat, etc. in the mission case, it is advantageous in terms of simplification of the structure and reduction of production cost. Further, the filter can be easily connected to the hydraulic block, and it is not necessary to provide a pipe or the like for connecting the filter and the hydrostatic continuously variable transmission on the outside of the hydraulic block, which simplifies the structure. In addition to being more advantageous, the vibration of the hydrostatic continuously variable transmission can be suppressed, so that the riding comfort of the work vehicle is also improved.

According to the features of claim 2, the "effect of the invention" of claim 1 is provided as in the case of claim 1. According to the feature of claim 2, when the valve block equipped with the on-off valve that secures the pressure on the upstream side (pump side) of the filter is provided, the mission case is provided with a dedicated opening for supporting the valve block, a connecting seat, or the like. Since it is not necessary to newly provide it, it is further advantageous in terms of simplification of the structure.
Further, since the vibration of the hydrostatic continuously variable transmission can be further suppressed, the riding comfort of the work vehicle becomes good.

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 configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is an overall side view of a riding lawn mower.

FIG. 2 is a side view showing a transmission system of a riding lawn mower.

FIG. 3 is a side view showing the outline of the transmission system of the mission case.

FIG. 4 is a longitudinal sectional side view of a transmission case.

[Fig. 5] Side view in vertical section near the dual one-way clutch

FIG. 6 is a cross-sectional plan view around the filter and the valve block.

FIG. 7 is a vertical sectional side view in the vicinity of a filter and a valve block.

FIG. 8 is a rear view of the vicinity of the filter and the valve block.

FIG. 9 is a hydraulic circuit diagram of a riding lawn mower.

[Explanation of symbols]

 5 mission case 6 hydrostatic stepless transmission 9 hydraulic block 34 on-off valve 35 filter 39 valve block 40 oil passage

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hironori Dobashi, 64 Ishizukita-machi, Sakai City, Osaka Prefecture Kubota Sakai Factory Co., Ltd. (72) Shuji Fujiwara, 64, Ishizukita-machi, Sakai City, Osaka Prefecture Kubota Sakai Manufacturing Co., Ltd. (72) Inventor Teruo Shimamura 64 Ishizukita-machi, Sakai City, Osaka Prefecture Kubota Sakai Manufacturing Co., Ltd. (72) Inventor Yoshikazu Togoshi 64, Ishizukita-machi, Sakai City, Osaka Prefecture (72) Inventor, Kubota Sakai Factory Akio Matsui 64 Ishizukita-cho, Sakai City, Osaka Prefecture Kubota Sakai Works

Claims (2)

[Claims] 1. A hydraulic block (9) having an oil passage therein is connected to one side of a mission case (5) for traveling, the hydraulic block (9) being opposite to the mission case (5). A hydrostatic continuously variable transmission (6) for traveling is connected to an outer surface of the filter, and a filter (35) is connected to the hydraulic block (9) so that hydraulic oil is supplied to the filter (35) and the hydraulic pressure. A hydraulic circuit structure for a work vehicle configured to replenish the hydrostatic continuously variable transmission (6) through an oil passage (40) provided in a block (9). 2. The filter (35) is sandwiched by a valve block (39) having an opening / closing valve (34) for securing a pressure of hydraulic oil on the upstream side from the filter (35), and the filter (35) is connected to the hydraulic block (35). 9. The hydraulic circuit structure for a work vehicle according to claim 1, which is connected to 9).