JP2003329111A - Cooling device for working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a cost and to simplify fixing work of a connection pipe by shortening a hydraulic pipe for connecting an oil cooler for cooling working oil of a hydrostatic continuously variable transmission. <P>SOLUTION: In a working vehicle wherein left and right crawler running devices 14 are driven by the hydrostatic continuously variable transmission (HST) composed of left and right hydraulic pumps 21 and hydraulic motors 25, a cooling fan 26 is driven by a PTO shaft 21b of the hydraulic pump 21, and the oil cooler 18 is disposed oppositely to the cooling fan 26. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a working vehicle, and more particularly to a hydrostatic continuously variable transmission (HST) for driving left and right crawler traveling devices. The present invention relates to a device for cooling hydraulic oil by an oil cooler. 2. Description of the Related Art Conventionally, an agricultural tractor as a working vehicle has a battery 16 in front of a cooling fan 15 driven by an engine 3 mounted on the tractor 1 as shown in an exploded plan view of FIG. A condenser 17 for changing the state of a high-temperature, high-pressure gaseous refrigerant sent from a compressor of an air conditioner to a liquid refrigerant, a hydrostatic continuously variable transmission (HST)
An oil cooler 18 and a radiator 19 for cooling the hydraulic oil are arranged in series, and the condenser 17, the oil cooler 18 and the radiator 19 are cooled by the blast of the cooling fan 15. The left and right hydraulic pumps 21 of the HST are disposed on a transmission case 20 that houses a PTO transmission at the rear of the machine body.
Had been placed. And, a hydrostatic continuously variable transmission (HS)
T), the hydraulic oil is circulated between the hydraulic pump 21 constituting the crawler traveling device and the hydraulic motor 25 attached to the drive sprocket of the crawler traveling device, so that the left and right crawler traveling devices 14 are circulated.
The hydraulic oil drained by the hydraulic motor 25 merges with the hydraulic oil drained by the hydraulic pump 21,
Also, the joined hydraulic oil enters the oil cooler 18 via the hydraulic pipe 23a and is cooled, and the cooled hydraulic oil returns to the hydraulic oil tank 22 via the hydraulic pipe 23b, and
The operating oil is supplied from the operating oil tank 22 to the charge pump 24.
To supply hydraulic fluid to the HST circulation circuit. The hydraulic pump 21 is driven by the power of the engine 3 via a coupling (not shown) and a transmission mechanism provided in the transmission case 20. [0003] However, in the tractor described above, in order to arrange the oil cooler in the engine room at the front of the fuselage, a connection pipe between the oil cooler and a hydraulic pump arranged on a transmission case is provided. In addition, the connecting pipe between the oil cooler and the hydraulic oil tank arranged on the side of the transmission case becomes very long, and the work of fixing the hydraulic pipe at a plurality of locations is required, resulting in problems such as an increase in cost. Furthermore, since the hydraulic pump was not provided with a special cooling fan, the surface temperature of the hydraulic pump itself could not be reduced.
An object of the present invention is to improve the above-mentioned conventional problems. [0004] In order to achieve the above object, the present invention provides an operation for driving left and right crawler traveling devices by a hydrostatic stepless transmission comprising left and right hydraulic pumps and a hydraulic motor. In a vehicle, the hydraulic pump P
The cooling fan is driven by the TO shaft, and the operating oil of the hydrostatic continuously variable transmission is cooled by an oil cooler arranged opposite to the cooling fan. An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall side view of an agricultural tractor as a working vehicle according to the present invention, and FIG. 2 is a rear view of the same, wherein 1 is a tractor, 2 is a body frame, and a normal tractor is mounted on the body frame 2. Similarly, a hood 4, a cabin 5, and the like, which house the engine 3 from the front, are provided. In the cabin 5, a driving control section including a driving seat 6, various operation levers, various switches, and the like. 7 is provided. [0006] A work implement lifting device 8 for mounting a work implement for performing various agricultural works is provided at a lower rear portion of the cabin 5. That is, the work machine elevating device 8 includes a pair of left and right lift arms 10, 10 rotatably supported on the upper portions of a pair of mounting plates 9, 9 erected at the rear of the tractor 1, and the lift arms 10, 10. Left and right lower links 12, 12 connected to the distal end of the vehicle via lift rods 11, 11, and lower ends thereof connected to the body frame 2 and upper ends thereof connected to intermediate portions of the left and right lift arms 10, 10. A conventional three-point link mechanism is generally used for the work machine elevating device 8. Further, 14 and 14 are crawler traveling devices provided on the left and right. FIG. 3 shows a traveling hydraulic circuit (HS) of the tractor 1.
T hydraulic circuit) and a hydrostatic continuously variable transmission A (HS
T) circulates hydraulic oil between the left and right hydraulic pumps 21, 21 and the left and right hydraulic motors 25, 25 for rotating the drive sprockets S of the left and right crawler traveling devices 14,
The hydraulic oil drained by the hydraulic motor 25 flows into the hydraulic pump 21 via the hydraulic pipe B, merges with the hydraulic oil drained by the hydraulic pump 25, and flows to the oil cooler 18 via the hydraulic pipe 23a. The hydraulic oil that has been cooled and cooled by the oil cooler 18 returns to the hydraulic oil tank 22 via the hydraulic pipe 23b. The hydraulic oil lost by the hydraulic pump 21 and the hydraulic motor 25 is transferred to the charge pump 24.
Hydraulic oil sucked up from the hydraulic oil tank 22 by the filter F and passed through the hydraulic pipe C through the HST
Is supplied to the circulation circuit D. The HST changes the swash plate position of the hydraulic pump 21 via a hydraulic servo mechanism, so that the rotation direction and speed of the hydraulic motor 25 are determined. FIG. 4 is a developed plan view of the tractor,
A battery 16, a condenser 17, and a radiator 19 are arranged in series from the front side in front of a cooling fan 15 of the engine 3 mounted on the tractor 1, and left and right hydraulic pumps 21 are mounted on a transmission case 20 containing a PTO transmission. PT extending behind the hydraulic pump 21
The cooling fan 26 is mounted on the O-axis 21b,
Further, an oil cooler 18 that cools the hydraulic oil of the HST is disposed upright on the body frame 2 so as to face the cooling fan 26. A hydraulic oil tank 22 is provided on the side of the transmission case 20.
Are also arranged. Therefore, the engine room 27 can be made compact because the oil cooler 18 is not provided, thereby shortening the overall length of the body and reducing the tractor 1
The turning radius of the vehicle can be reduced, and the amount of overhang of the front of the body is reduced, so that the climbing angle at the time of loading on a truck or the like can be increased. The PT of the hydraulic pump 21 disposed on the transmission case 20 is
The cooling fan 26 driven by the O-shaft 21b allows the cooling air to flow from the front side to the rear side of the fuselage while the engine 3 is driven, so that the oil cooler 18 is cooled thereby and the hydraulic pump 21 itself Surface temperature can be reduced. Further, since the oil cooler 18 is disposed so as to face the cooling fan 26 and is disposed near the hydraulic pump 21 and the hydraulic oil tank 22, the hydraulic pipes 28a and 28b connected thereto are conventionally provided. The length of the hydraulic piping 23a and 23b can be reduced, and the work of fixing the hydraulic pipes 23a and 23b at a plurality of locations becomes unnecessary. Next, the crawler traveling device 14 of the present invention will be described. As shown in FIG. 5, the movable roller 29 on the front side of the crawler traveling device 14 can be adjusted to an arbitrary upper and lower position by moving the crawler traveling device 14. The posture can be changed. Conventionally, since the traveling posture of the crawler traveling device 14 was constant, it was not possible to always obtain a traveling posture of the crawler traveling device 14 that was adapted to work conditions such as a field or a road. Therefore, the axial support of the movable wheel 29 on the front side of the crawler traveling device 14 can be vertically moved, and the position can be vertically moved and fixed by the hydraulic cylinder 30, a motor, a worm gear, or the like. Therefore, during the normal traveling shown in FIG. 5, there is an appropriate crawler approach angle θ between the driving sprocket 31 and the first wheel 32, and the contact length l of the crawler traveling device 14 is short, such as during turning or high speed. Friction with the ground during running can be reduced and standard running performance can be obtained. FIG.
When the movable rolling wheel 29 is moved upward to be fixed, and the traveling posture is such that the crawler approach angle θ is eliminated, the contact length L of the crawler traveling device 14 increases, whereby the tractor 1 becomes more resistant to forward and backward swing and slips. Since it becomes difficult, the traction force can be increased. FIG. 7 shows that, when the movable rolling wheel 29 is moved downward by the hydraulic cylinder 30 and fixed to the working posture where the crawler approach angle θ is increased, the mud pushing by the front of the crawler is performed even when the aircraft sinks in a soft field. Can be prevented and traveling can be enabled. Therefore, the operator can select the traveling posture of the tractor 1 according to the situation, and can always maintain stable traveling performance. As described above, according to the present invention, the left and right crawler traveling devices 14 are connected to the left and right hydraulic pumps 21 and the hydraulic motors 25.
In the working vehicle 1 driven by the hydrostatic continuously variable transmission A composed of the PTO shaft 2 of the hydraulic pump 21
1b drives the cooling fan 26 and cools the hydraulic oil of the hydrostatic continuously variable transmission A by the oil cooler 18 arranged opposite to the cooling fan 26. The connecting hydraulic pipes 28a and 28b of the oil cooler 18 for cooling the hydraulic oil of the device A can be shortened, and the work of fixing the hydraulic pipes 28a and 28b at a plurality of locations can be simplified and unnecessary. Cost can be reduced. The hydraulic pump 2 is driven by a cooling fan 26 driven by a PTO shaft 21a of the hydraulic pump 21.
1 The surface temperature of the oil cooler itself can be reduced, and by arranging the oil cooler 18 in series with the radiator 19 and the like as in the prior art, the cooling air is weakened and the cooling performance is not hindered. Cooling fan 2
6, the oil cooler 18 is directly cooled, and the cooling efficiency can be improved.

[Brief description of the drawings] FIG. 1 is an overall side view of an agricultural tractor. FIG. 2 is a rear view of the same. FIG. 3 is a hydraulic circuit diagram. FIG. 4 is a developed plan view of the agricultural tractor of the present invention. FIG. 5 is a standard side view of the crawler traveling device. FIG. 6 is a side view showing the same forward leaning posture. FIG. 7 is a side view showing the upper inclined posture. FIG. 8 is a developed plan view of a conventional agricultural tractor. [Explanation of symbols] 1 tractor 2 Airframe 14 Crawler traveling device 18 Oil cooler 21 Hydraulic pump 22 Hydraulic oil tank 25 Hydraulic motor 26 Cooling fan

Claims (1)

Claims 1. An operation of driving a left and right crawler traveling device (14) by a hydrostatic continuously variable transmission (A) comprising left and right hydraulic pumps (21) and a hydraulic motor (25). In the vehicle (1), a cooling fan (26) is driven by a PTO shaft (21b) of the hydraulic pump (21), and an oil cooler (18) disposed opposite to the cooling fan (26) causes a hydrostatic pressure. A cooling device for a working vehicle, which cools hydraulic oil of a continuously variable transmission (A).