GB2298622A

GB2298622A - Working vehicle

Info

Publication number: GB2298622A
Application number: GB9609859A
Authority: GB
Inventors: Satoru Nishimura; Noboru Kanayama
Original assignee: Komatsu Ltd
Current assignee: Komatsu Ltd
Priority date: 1993-11-12
Filing date: 1994-11-04
Publication date: 1996-09-11
Anticipated expiration: 2014-11-04
Also published as: DE4498697T1; KR960705697A; WO1995013202A1; GB9609859D0; GB2298622B

Description

DESCRIPTION WORKING VEHICLE TECHNICAL FIELD The present invention relates to a working vehicle.

More particularly, the invention relates to a working vehicle improving traveling stability and efficiency with a function to shorten its length and width.

BACKGROUND ART Hitherto, a conventional working vehicle is comprised an upper rotating component mounted on a lower traveling component, and conducts certain work by operating a working apparatus, e.g. a bucket, on the top of booms and arms mounted on the upper rotating component. This type of vehicle mounts an engine on the upper rotating component and the engine drives a hydraulic pump which provides hydraulic pressures for both driving the vehicle and operating the working apparatus. The hydraulic pressures for driving the vehicle is guided through a swivel joint to the lower traveling component and changed into a torque by a hydraulic motor mounted on the lower traveling component. The torque is transmitted and drives the wheel axle through a reduction apparatus, etc.

In such construction where a driving unit is mounted on the upper rotating component, the driving power has very low efficiency in high speed travel range because it is created by the hydraulic pressures. Moreover, the vehicle can not but to use the low speed travel range at the public road because the high center of gravity of the vehicle causes instability during travel.

Conventionally, in such working vehicles, other popular construction would be where the engine of a rough terrain crane vehicle is mounted on the overhung rear frame, extended from the rear wheel of the lower driving component.

In another case, the driving unit, including the engine of a high stage working vehicle with a telescopic forks, is mounted on the overhung side frame of the lower frame.

However, there are problems in the former case that the length of vehicle is extended and in the latter case the width of vehicle is extended so that it results in the lateral instability of the vehicle.

DISCLOSURE OF INVENTION Accordingly, in order to overcome the above-mentioned drawback inherent in the background art, an objective of this invention enables working vehicle, comprising an upper rotating component mounted on a lower travelling component, a high speed travel at a public road. This is made possible by improved construction making the length and width of the vehicle compact and improving the stability at high speed travel.

According to the first aspect of the present invention, it is characterized in that a driving unit including an engine is mounted between a front driving shaft and a rear driving shaft including one of nearby parts of the front driving shaft and the rear driving shaft and by that it results that the gravity of the engine of the driving unit is arranged to be inside of chassis frame. This driving unit between the engine and driving axles should have at least one of a mechanical connection and a connection through a torque converter. Hereof the torque converter, etc, means the devices which hydraulically transmits the the torque and include mechanical transmitting device with lock-up mechanism which is commonly used in such working vehicles.At the same time, the position of the driving unit may be located inside of chassis frame and either between the front driving shaft and the swivel joint including nearby parts of the front driving shaft and the swivel joint, or between the rear driving shaft and the swivel joint including nearby parts of the rear driving shaft and the swivel joint. Furthermore, the center of the engine and the center of an input shaft of a differential apparatus are layouted in an offset position with each other, seeing from the direction of the top of the vehicle.

This offset construction is divided into the left and right to the center of the front and rear direction of the lower traveling component. The driving unit is equipped with a hydraulic pump and a hydraulic motor, and the shaft of the hydraulic pump and motor are mounted in an offset position on the one side of the transmission. In this power transmitting mechanism of the driving unit, the driving power is transmitted from the hydraulic pump to the hydraulic motor in low speed range and transmitted from the engine to driving axles through the mechanical connection in high speed range. Moreover, a generator can be used instead of the hydraulic pump and an electrical motor can be used instead of the hydraulic motor.

With this construction, the stability during travel is improved by making the center of gravity lower and making the length and width shorter by the midship layout of the driving unit, including the engine. At the same time, travel efficiency is improved by making the driving unit to apply two different driving mechanisms, which are the connection through the torque converter or the mechanical connection, upon necessity. Moreover, the length of the driving unit may be shortened when applying the mechanism without the torque converter. Further, it would make the vehicle compact by avoiding the interference of the engine and the differential apparatus by adopting one of the layout of offset construction and to offset them in the driving shaft position opposite of the swivel joint.As a hydraulic pump is equipped in the driving unit, the pressured oil generated by the hydraulic pump can be supplied into an an actuator to actuate the working apparatus and also supplied into the driving hydraulic motor to drive the working vehicle. Moreover, the length of the driving unit including the hydraulic pump and motor can be shortened and make the vehicle more compact because the hydraulic pump and motor is mounted on the driving unit in the offset position. The length of the lower driving component is also shortened because the distance between the shaft where the driving unit is mounted and the swivel joint is shortened as shown on the drawing 2, for the driving unit may be divided into the left and right of the swivel joint.

Moreover, the efficiency of travel is greatly improved because the torque is transmitted between the hydraulic pump and motor in low speed range, and the torque of engine is directly transmitted to the axle through power transmitting mechanism in high speed range.

Accordingly to the second invention of the working vehicle, it is characterized in the layout that the center of gravity of the engine is located between the swivel joint and one of pair of the front and the rear axles, the driving unit having at least one of a connection which mechanically connects the engine with the other pair of axles and a connection comprising hydraulic pump(s) connected with the driving unit, and the hydraulic motors driven by the hydraulic pump(s) connected with each driving axle in the left and right of the vehicle located on the same side of the engine. Therefore, the left and right axles are driven by hydraulic motors and other pair of the axles are driven by the driving unit.These driving method is interchangeable among one of each method or both of which the pair of axles in the engine-mounted-side are driven by the hydraulic motors and the other pair of axles are driven by the mechanically connected driving unit. Further, the generator can be used instead of the hydraulic pump and the electrical motor can be used instead of the hydraulic motor.

According to this construction, a torque shaft, a differential gear, etc, with which are usually connected between the engine and axles are eliminated because the hydraulic driving method by the hydraulic motors mounted on the front wheels (or the rear wheels) and the driving unit connected with the rear wheels (or the front wheels) are used together. Therefore, the layout of the driving unit including the engine can be selected more freely and can make the vehicle more compact. Moreover, the selection between two wheels drive and four wheels drive is available depending on the driving purpose. For example, four wheel drive is selected during work in low speed range and two wheel drive is selected during drive in high speed range.

BRIEF DESCRIPTION OF THE DRAWING Fig. 1 illustrates a side view of the working vehicle according to a first embodiment of the present invention Fig. 2 illustrates a layout for driving unit, etc, according to a first embodiment of the present invention Fig. 3 is avertical front view of the lower driving component according to a first embodiment of the present invention Fig. 4A is top plain view and Fig. 4B is a side view of the outline of the driving unit according to a first embodiment of the present invention Fig. 5 is a schematic view of the power train of the working vehicle according to a first embodimentof the present invention Fig. 6 illustrates the layout fordriving unit, etc, according to a second embodiment of present invention Fig. 7 illustrates a layout for driving unit, etc, according to a third embodiment of the present invention Fig. 8 illustrates a layout for the lower driving component according to a fourth embodiment of the present invention.

THE BEST MODE FOR CARRYING OUT THE INVENTION The preferred embodiments of the present invention for a working vehicle is discussed below with reference to the accompanying drawings.

Fiss. 1, 2, 3, 4A and 4B show the construction of the working vehicle related to the embodiment 1, comprising a lower driving component 10 and an upper rotating component 12 mounted on the lower driving component 10 through a swivel joint 36. The upper rotating component 12 is comprised an operating room 16 and a working apparatus 14 which can be lifted up and down. The working apparatus 14 is comprised a pair of booms 18 supported on the upper rotating component 12, a pair of arms 20 connected to the top of the booms 18 and a bucket 22at the top of the arms 20. On the working vehicle in this invention, boom 18 is located on both sides of the vehicle and is comprised a first boom 18A and a second boom 18B that are connected with a pin.When the the boom 18 is folded in stand-by position, it is designed to be protruded from the front or rear frame of the lower travelling component 10 as small as possible and to be located lower enough not to prevent the visibility an operator.

Both the first boom 18A and the second boom 18B is formed in bell-crank type. The curved part of the first boom 18A is mounted with support pin 23 on the upper rotating component 12 in the rather front part of the center of the swivel joint to enable it to lift up and down. One end of the first boom 18A is fixed with the rear end of the second boom 18B through a hydraulic cylinders 24. The hydraulic cylinder 24 actuates the second boom 18B to raise against the first boom 18A when the cylinder 24 extends.

It is also designed that hydraulic cylinder 26, with which the curved part of the second boom 18B is mounted on the upper rotating component 12 actuates the second boom 18B to raise against the upper rotating component 12.

Therefore, the working vehicle is designed to keep the center of gravity low because the working apparatus 14 is constructed to remain low while it its in its stand-by position.

Moreover, in this embodiment, it is constructed that the driving unit 30 is mounted on the lower driving component 10 which supports the upper rotating component 12. Whereon the lower driving component 10 is equipped with the U-shaped frame 34 in cross section (refer to Fig. 3) which encloses the engine and other basic components. Therefore, it is constructed that the driving unit 30 is mounted of inside the U-shaped frame 34, which would be the chassis frame.In this case, the driving unit 30 is located between the front driving shaft 38 and the swivel joint 36 which penetrates a fixed surface 32 in the lengthwise direction of the vehicle. Especially, the driving unit 30 is constructed so that the engine 40 and transmission 42 is located at the front side, and the rear part of transmission 42 is equipped with the hydraulic pump 43 overhung on the right side and the hydraulic motor 44 overhung on the left side. This layout avoids the interference of the hydraulic pump 43 and the hydraulic motor 44 to the swivel joint 36 (refer to Fig 2, Fig. 4A and Fig. 4B).

Furthermore, the engine 40 is located and overlapped above the front driving shaft 38 so that it makes the front driving shaft 38 unit compact. Moreover, the height Whw of the lower driving component 10 is lowered, and, the distance "L1" between the swivel joint 36 and the front axle 51 and wheelbase "L2" is shortened by the independent suspension method. For this purpose, as shown in Fig. 3, the front axle 51 is supported with suspension 46 which are connected with side flange 34A overhanging from the side of U-shaped frame 34, and link 49 rotatively connected with U-shaped frame 34. The front driving shaft 38 equipped with a differential apparatus 48 and constant speed joints 50 which distribute the torque to left and right axles.The differential apparatus 48 is located in either the left or right offset position in this embodiment, because it would interfere with the engine 40 if it is located in the center of the vehicle. Against this offset layout of the differential apparatus 48, the engine 40 is located in the other offset position to avoid interference with each other and also to overlap with the front driving shaft 38.

As mentioned above, the engine 40 is arranged to be in midship position because it is located between the wheelbase L2 including the above part of the front driving shaft 38 of the lower driving component 10. This power train from the engine 40 is different from a multi-stage transmission with torque converter. Namely, in the power train of this embodiment, it is conducted that the first and second stage of low speed ranges are hydraulically driven by the hydraulic motor 44 and over third stage of high speed ranges are driven by the direct type transmission. Fig. 5 shows the power train of this driving system. The input into transmission 42 mentioned above are done through the output shaft 52 of the engine 40. At high speed range, the engine output through the output shaft 52 will change the gear ratio actuated by the selective sliding mechanism by third, fourth and fifth stage of clutch 54. At the same time, the output shaft 52 is transmitting the torque to the hydraulic pump 43 and conducts pump function. The output shaft 56 of the hydraulic motor 44 driven by hydraulic pressures from the hydraulic pump 43 functions as the input shaft to the transmission 42 as well. At low speed range, the engine output through the output shaft 56 will change the gear ratio actuated by the selective sliding mechanism by first and second stage clutch 58. Therefore, torque selected from a planetary gear train is transmitted to the output shaft 60 of transmission 42 and then transmitted from the output shaft 60 to the front driving shaft 38.In the vehicle of this embodiment, the driving power is transmitted to the front driving shaft 38 and the rear driving shaft 39 because it has four wheel driving method.

According to this construction, the space for the torque converter is eliminated so that it enables to shorten the length of mounted space for the driving unit 30. By this means1 the driving unit 30 can be compactly mounted inside the U-shaped frame 34. Moreover, at the same time, the hydraulic pump 43 and motor 44 are compactly mounted inside the U-shaped frame 34, similar to auxiliary device.

Further, the output of the hydraulic pump 43 is supplied not only to the hydraulic motor 44 but also to the hydraulic motor for rotating the upper rotating component 12 and cylinders of the working apparatus 14 (not shown in figure) through pipings. The pressured oil is transmitted inside of the swivel joint 36 and is guided to the upper rotating component 12.

According to the construction of this embodiment, it enables the upper surface of the lower traveling component 10 to be flat because the comparatively heavy weight driving unit 30 including the engine 40 and the transmission 42, etc, is compactly mounted inside the lower traveling component 10. Therefore, visibility is drastically improved and the lower traveling component 10 can be applied to the other working vehicle as a common unit. Moreover, this vehicle can travel in more than 50 km/h on the public road because the low center of gravity "G" makes excellent travel stability.Further, driving power is not supplied from the upper rotating component 12 but is directly supplied from the driving unit 30 inside the lower traveling component 10 so that the travel efficiency is improved to more than 90 X against 70 X of the conventional method.

Moreover, accordingly to this embodiment, the hydraulic pump 43 for driving power can be used as a working pump during working hours, because it takes the driving method that the vehicle is driven by the hydraulic motor 44 in low speed range and by the direct transmission 42 in high speed range. By this means, it is economically constructed because the hydraulic pump 43 can supply the pressured oil to the swivel joint 12 and the working apparatus 14 for work. Furthermore, because the width and length of the vehicle are short by the low center of gravity "G" and the compactness of the driving unit 30, the turning radius of the lower traveling component 10 becomes smaller and the maneuverability of the working vehicle is significantly improved.Further, this embodiment only shows that the driving unit 30 is located between the swivel joint 36 and the front driving shaft 38, however, the driving unit 30 may be located between the swivel joint 36 and the rear driving shaft 39.

Another embodiment, which relates to the different layout of the driving unit compared to the above embodiment 1 is discussed below with reference to the accompanying drawings.

Fig. 6 shows the embodiment 2 that the driving unit is divided into engine 40 and driving unit 30, the part other than engine 40, and both is connected by propeller shaft 31.

Fig.7 shows the third embodiment that. similar to embodiment 2, the driving unit 30 except the engine 40 is located in the rear part of the vehicle and connected with the engine 40 by the propeller shaft 31. Further, it is constructed that hydraulic pump 43 and hydraulic motor 44 are connected with swivel joint 36 side of transmission 42. According to such construction of embodiment 2 and embodiment 3, the wheelbase L2 can further be shortened than embodiment 1 because the driving unit 30 is layouted in divided position.

Embodiment 4 relates to the working vehicle of this invention, which is discussed below with reference to Fig. 8.

Fig. 8 shows the embodiment 4 that the driving unit 30 is mounted among the swivel joint 36 of the lower driving component and rear axles of rear wheels 71 and 71. The driving unit 30 is equipped at least with the engine 40, the transmission 42 connected with engine and the hydraulic pump 45. The left and right rear axles at the side of the engine 40 (side of rear wheels 71 and 71) are equipped with hydraulic motors 80 and 80, driven by hydraulic pump 45.

The drive with the rear wheels 71 and 71 driven by the hydraulic motors 80 and 80, and with the front wheels 72 and 72 driven by the transmission 42 may be interchangeable among one of each or both. The explanation has been made with the example that the driving unit 30 is mounted among the swivel joint 36 and rear axles of rear wheels 71 and 71.

However, the driving unit 30 can also be mounted among the swivel joint 36, and front axles of front wheels 72 and 72.

In this case, the hydraulic motors 80 and 80 are connected with the left and right rear axles of the front wheels 72 and 72.

Accordingly to this construction, for example, the working vehicle is driven by the hydraulic drive in low speed range and by direct drive in high speed range.

Further, for example, four wheels are driven by the hydraulic drive in low speed range. and two wheels are driven by the hydraulic drive and the other two wheels are driven by the direct drive in high speed range. Accordingly to the above mentioned embodiment 4, as the same to embodiment 1, the length of mounted space for the driving unit 30 can be shortened because the space for torque converter is eliminated. Moreover, in the case where the hydraulic motors 80 and 80 is mounted, more compact vehicle is achieved because not only the driving shaft but also differential apparatus 48 is eliminated. Further in these emodiments, the generator is used instead of the hydraulic pump 45 and the electrical motor is used instead of the hydraulic motors 80 and 80. The effect of this case would be the same to the before mentioned embodiments.

INDUSTRIAL APPLICABILITY This invention is applicable to the working vehicle that can travel in high speed on the public road because the low center of gravity makes it stable in high speed travel, and that has high travel efficiency because it has two driving systems for both low speed range and for high speed range1 and that the shortening of the length and width makes it compact because the torque converter, etc., is eliminated.

Claims

1. A working vehicle, comprising ; an upper rotating component equipped with a working apparatus, and a lower traveling component supporting said upper rotating component through a swivel joint, wherein a driving unit including an engine is mounted between a front driving shaft and a rear driving shaft including one of nearby parts of the front driving shaft and the rear driving shaft, whereby the center of gravity of said engine is arranged to be inside of chassis frame.

2. A working vehicle according to claim 1, wherein said driving unit between the engine and driving axles has at least one of a mechanical connection and a connection through a torque converter.

3. A working vehicle according to claim 2, wherein said driving unit is mounted, either between the front driving shaft and the swivel joint including nearby parts of the front driving shaft and the swivel joint, or between the rear driving shaft and the swivel joint including nearby parts of the rear driving shaft and the swivel joint.

4. A working vehicle according to claim 1, wherein the center of said engine and the center of an input shaft of a differential apparatus are mounted in an offset position with each other seeing from the top of the vehicle.

5. A working vehicle according to claim 4, wherein said offset position is divided into the left and right to the center of the front and rear direction of said lower travelling component.

6. A working vehicle according to one of claims 1 and 2, wherein said driving unit is equipped with a hydraulic pump and with a hydraulic motor1 and a shaft of said hydraulic pump and a shaft of said hydraulic motor are mounted on one side of the transmission in an offset position to each other.

7. A working vehicle according to claim 6, wherein in a power transmitting mechanism of said driving unit, the driving power is transmitted from said hydraulic pump to said hydraulic motor in low speed range and transmitted from said engine to said axles through said mechanical connection in high speed range.

8. A working vehicle, comprising; an upper rotating component equipped with a working apparatus and a lower traveling component supporting said upper rotating component through a swivel joint, wherein said working vehicle comprises an engine of which the center of gravity is arranged between said swivel joint and one pair of the front and the rear axles, a driving unit having at least a connection which mechanically connects said engine with the other pair of said axles, a hydraulic pump connected with said driving unit, and hydraulic motors driven by said hydraulic pump and mounted on the left and right axles located on the same side of said ensine, whereby said left and right axles are driven by said hydraulic motors, and other pair of said axles are driven by said driving unit.

9. A working vehicle according to claim 8, wherein said axles are driven by said hydraulic motors or said mechanically connected driving unit, or both driven by said hydraulic motors and said mechanically connected driving unit selectively.

10. A working vehicle according to one of claims 7, 8 and 9, wherein said hydraulic pump is a generator and said hydraulic motor is an electrical motor.