JP2006027432A - Hydraulic travel shift device in travel work machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continuously shift traveling speed by an oil pressure in a travel work machine in which an engine 5 and a transmission case 8 for transmitting power to traveling means are mounted on a travel machine body supported by the traveling means such as wheels 3, 4 or the like. <P>SOLUTION: A hydraulic pump 21 rotated by the engine is provided and whereas two cam plate type axial piston motors 22, 23 are connected to a power transmission part to the traveling means in series. A hydraulic circuit constituted such that the oil pressure of a delivery port of the hydraulic pump to both axial piston motors and the oil pressure from discharge ports of both axial piston motors is returned to the hydraulic pump is provided between the both axial piston motors and the hydraulic pump. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic travel transmission for arbitrarily shifting the travel speed of a travel work machine such as a tractor used for agricultural work or a wheel loader used for civil engineering work.

  Conventionally, a hydraulic traveling transmission device in this type of traveling work machine, for example, as described in Patent Document 1 or the like, rotationally drives a hydraulic pump with an engine, The swash plate type axial piston pump is supplied to the axial piston pump, and the axial working pump is driven to rotate. The traveling working machine is driven and driven, and the tilting angle of the inclined plate in the axial piston pump is adjusted to adjust the inclination angle. The traveling speed of the traveling work machine is changed.

In this conventional hydraulic travel transmission, the speed ratio of the axial piston pump is narrow, so that, apart from the axial piston pump, the rear side of the power transmission, that is, from the axial piston pump to the traveling wheel, etc. A sub-transmission mechanism is provided to reach the travel means, and the traveling speed of the axial piston pump is appropriately changed between high-speed travel and low-speed travel by the sub-transmission mechanism. .
JP 7-117500 A

  However, providing a sub-transmission mechanism for shifting the traveling speed between high-speed traveling and low-speed traveling on the rear side of the power transmission in the axial piston pump in this way complicates the structure and increases the size and In addition to incurring an increase in weight, there was a problem that the shifting operation was considerably troublesome.

  An object of the present invention is to provide a hydraulic travel transmission that solves this problem.

In order to achieve this technical problem, claim 1 of the present invention provides:
“In a traveling working machine comprising a traveling machine body supported by traveling means such as wheels and an engine and a transmission case for transmitting the power of the engine to the traveling means,
The transmission case is provided with a hydraulic pump that is rotationally driven by the engine, and two swash plate type axial piston motors are connected in series to the power transmission part to the traveling means in the transmission case. A hydraulic circuit is provided between the axial piston motor and the hydraulic pump so that the hydraulic pressure from the discharge port of the hydraulic pump is supplied to both axial piston motors, and the hydraulic pressure from the discharge port of both axial piston motors is returned to the hydraulic pump. Provide. "
It is characterized by that.

Further, claim 2 of the present invention is
“In the first aspect of the present invention, a lid plate for detaching the extraction window formed in the mission case is detachably attached to the mission case, and the hydraulic pump and the both sides are mounted on the front and back surfaces of the lid body. Attach one of the axial piston motors and the other on the back. "
It is characterized by that.

Furthermore, claim 3 of the present invention provides
“In the description of claim 2, the hydraulic circuit is provided inside the lid plate.”
It is characterized by that.

  In the configuration of claim 1, the hydraulic pressure from the discharge port of the hydraulic pump is simultaneously supplied to both axial piston motors via a hydraulic circuit, so that the two axial piston motors are discharged from both axial piston motors. The hydraulic pressure from the outlet is driven to rotate so as to be returned to the hydraulic pump via a hydraulic circuit.

  In this case, the swash plate in one of the axial piston motors is operated to the maximum tilt angle, while the swash plate in the other axial piston motor is operated at the minimum tilt angle including the position where the tilt angle is zero and the minute tilt angle. When operated to an angle, one of the two axial piston motors is driven to rotate mainly by hydraulic pressure from the hydraulic pump, so that the motor output side of the two axial piston motors has the maximum rotational speed. The traveling work machine can be shifted to high speed traveling.

  On the other hand, when the swash plates in both the axial piston motors are operated so as to reduce the inclination angle at the same time, the two axial piston motors are simultaneously driven to rotate by the hydraulic pressure from one hydraulic pump. Since the motor output side of the piston motor has a low rotational speed, the traveling work machine can be shifted to low speed traveling.

  Then, by operating the swash plate in both axial piston motors to an arbitrary inclination angle, the motor output side in both axial piston motors can be changed steplessly to an arbitrary rotational speed. The speed can be continuously changed to an arbitrary traveling speed between the high speed traveling and the low speed traveling.

  Therefore, according to the first aspect of the invention, the hydraulic travel transmission can shift to high speed travel, low speed travel, and travel at an arbitrary speed therebetween, and in some cases, the conventional subtransmission mechanism can be omitted. This makes it possible to achieve a significant reduction in size and weight, and to greatly simplify the speed change operation.

  Further, according to the invention according to claim 2, since the hydraulic pump and both axial piston motors can be assembled and disassembled with respect to the transmission case by attaching and removing the cover plate to the transmission case, the number of steps required for these can be reduced. ， Maintenance can be improved.

  Furthermore, according to the configuration described in claim 3, the hydraulic pump and both axial piston motors are mounted on the lid plate, and a hydraulic circuit is provided for connecting the hydraulic pump and the axial piston motor. Since the assembly and disassembly can be further reduced, the maintenance work can be further improved, and the hydraulic circuit is provided inside the lid plate, thereby further reducing the size and weight. Can be achieved.

  Hereinafter, drawings when the embodiment of the present invention is applied to a tractor as a traveling work machine will be described.

  1 and 2 show a tractor 1, which supports a traveling machine body 2 with a pair of left and right rear wheels 4 as well as a pair of left and right front wheels 3 and is mounted on the front portion of the traveling machine body 2. The engine 5 is configured to travel forward by driving the rear wheels 4 and the front wheels 3, and on the upper surface of the traveling machine body 2, the control seat 6 and the front wheels 3 are moved left and right. A steering handle 7 adapted to be steered by moving is provided, and at the rear part of the traveling machine body 2, the rotation of the engine 5 is appropriately shifted and transmitted to the rear wheels 4 and the front wheels 3. A mission case 8 is installed.

  In this case, both the rear wheels 4 are attached to the transmission case 8 so as to be detachably attached to the transmission case 8 so as to protrude outward from the outer surface of the transmission case 8, and the outer side of the axle case 9 It is attached via a gear case 10 mounted so as to extend rearward at the end, and an axle 4 a for the rear wheels 4 is inserted into the axle cases 9.

  A gear case 11 that covers the drive shaft 5 a on the engine 5 side is attached to the rear side of the engine 5, and a gear train mechanism 12 in the gear case 11 is connected to the lower portion of the gear case 11 from the drive shaft 5 a. The main shaft 13 to which power is transmitted is provided so as to protrude rearward, and the rear side surface of the gear case 11 is hydraulic to a working machine lifting mechanism 15 and a working machine hydraulic motor described below. A hydraulic pump 14 for working is attached so as to be directly connected to the drive shaft 5a.

  A hydraulic working machine lifting mechanism 15 for lifting and lowering a working machine (not shown) such as a tiller connected to the rear part of the traveling machine body 2 can be attached to and detached from the upper surface of the rear part of the mission case 8. Installed on. A PTO shaft 16 is provided at the rear of the mission case 8 so as to protrude rearward.

  Although not shown, the hydraulic fluid pressurized by the hydraulic pump 14 is supplied to the lifting mechanism 15 between the hydraulic pump 14 and the working machine lifting mechanism 15 and discharged from the lifting mechanism 15. A hydraulic circuit configured to return oil to the hydraulic pump 14 is provided. Of course, in this hydraulic circuit, the hydraulic switching for switching the lifting mechanism 15 to three stages of raising, lowering and lifting stop is provided. Needless to say, valves are provided.

  A telescopic power transmission shaft 19 having a universal shaft joint at both ends between the main drive shaft 13 projecting backward from the gear case 11 and the input shaft 18 projecting forward from the front surface of the transmission case 8. And the rotation of the engine 5 is transmitted from the drive shaft 5a to the input shaft 18 in the transmission case 8 through the gear train mechanism 12, the main drive shaft 13 and the power transmission shaft 19 in the gear case 11. Then, the transmission is appropriately shifted by a hydraulic travel transmission (HMT) 20 in the transmission case 8 and transmitted to the rear wheel 4 and both front wheels 3.

  As will be described below, the hydraulic travel transmission mechanism 20 is composed of a single hydraulic pump 21 for shifting and two swash plate type axial piston motors 22, 23 that are operated by the hydraulic pump 21. .

  That is, as shown in FIG. 3 and FIG. 4, a cover plate 24 that closes the extraction window 8b formed in the front surface 8a is detachably attached to the front surface 8a of the transmission case 8 by fastening bolts 25. The hydraulic pump 21 is mounted on the surface opposite to the transmission case 8 of the front and back surfaces of the cover plate 24 so that the input shaft 21a penetrates the cover plate 24 and protrudes into the transmission case 8. On the other hand, the lid plate 24 is pivotally supported so as to penetrate a single motor output shaft 26.

  One of the axial piston motors 22 and 23 is fitted on and attached to the motor output shaft 26 on the surface of the cover plate 24 opposite to the transmission case 8. The other axial piston motor 23 of the two axial piston motors 22, 23 is attached to the motor output shaft 26 on the back surface of the lid plate 24 on the transmission case 8 side. That is, the two axial piston motors 22 and 23 are connected in series with a single motor output shaft 26 penetrating the lid plate 24.

  In addition, although not shown, the hydraulic pressure from the discharge port of the hydraulic pump 21 is supplied to the cylinders of the two axial piston motors 22 and 23 inside the lid plate 24, and A hydraulic circuit that returns the hydraulic pressure from the discharge port of the cylinder to the hydraulic pump 21 is provided as a hydraulic passage.

  The reference numeral 27 is a cover casing for the one axial piston motor 22, and the pump casing in the hydraulic pump 21 may be integrated with the cover casing 27.

  In the mission case 8, the gear 28 fixed on the input shaft 18 is meshed with an input gear 31 that is rotatably fitted on a sun gear shaft 30 in the planetary gear mechanism 29. A plurality of planetary gears 33 are rotatably supported on a carrier 32 fixed to the input gear 31 via a support shaft 34, and each planetary gear 33 is fixed to the sun gear shaft 30. 35 and an inner ring gear 36 that is rotatably fitted on the sun gear shaft 30.

  Next, the gear 37 fixed to the inner ring gear 36 is engaged with a gear 40 on an input shaft 39 that is detachably coupled to the input shaft 21a of the hydraulic pump 21 via a shaft joint 38. While the transmission hydraulic pump 21 is driven to rotate, a gear 42 on an intermediate shaft 41 detachably connected to the motor output shaft 26 via a shaft joint 38 meshes with a gear 44 fixed on the sun gear shaft 30. Thus, the rotation of the motor output shaft 26 is transmitted to the sun gear shaft 30.

  On the other hand, a rear wheel propulsion shaft 45 is pivotally supported in the transmission case 8, and the rear end of the propulsion shaft 45 is connected to a conventionally known differential gear mechanism 46 for the two rear wheels 4. The rear wheel propulsion shaft 45 is configured to rotationally drive the rear wheels 4, while a gear 47 rotatably fitted on the propulsion shaft 45 is connected to the gear 44 on the sun gear shaft 30. On the other hand, when the clutch 48 is provided between the gear 47 and the propulsion shaft 45 and the clutch 48 is turned on, the rotation of the motor output shaft 26 is rotated via the sun gear shaft 30. When the power is transmitted to the rear wheel propulsion shaft 45 and the clutch 48 is turned off, the power transmission to the rear wheel propulsion shaft 45 is cut off.

  Further, the gear 48 on the rear wheel propulsion shaft 45 meshes with the gear 50 that is rotatably fitted on the front wheel propulsion shaft 49 that is pivotally supported in the transmission case 8, and the front wheel propulsion shaft is engaged. 49 and a conventionally known differential gear mechanism 51 for both the front wheels 3 are connected via telescopic power transmission shafts 52 having universal shaft joints at both ends. A clutch 53 is provided on the shaft 49, and when the clutch 53 is operated to be turned on so as to fix the gear 50 to the propulsion shaft 49, the rear wheel propulsion shaft 45 causes the two front wheels to move. 3 is driven to rotate, and the front wheel 3 is not driven to rotate when the clutch 53 is turned off.

  In this configuration, the hydraulic pump 21 in the hydraulic travel transmission (HMT) 20 is rotationally driven by power transmission from the engine 5, and the hydraulic pressure from the discharge port of the hydraulic pump 21 passes through both hydraulic circuits. By being supplied to the axial piston motors 22 and 23 at the same time, the hydraulic pressures from the discharge ports of the axial piston motors 22 and 23 are returned to the hydraulic pump 21 via the hydraulic circuit. In this way, it is driven to rotate.

  Therefore, as shown in FIG. 4, the swash plate 22a in one of the axial piston motors 22 and 23 is operated to the maximum inclination angle θ while the swash plate 23a in the other axial piston motor 23 is operated. When the tilt angle is set to the zero position and the minimum tilt angle including the minute tilt angle, one of the axial piston motors 22 and 23 is driven to rotate mainly by the hydraulic pressure from the hydraulic pump 21. As a result, the motor output shaft 26 of both the axial piston motors 22 and 23 has the maximum rotational speed, so that the traveling work machine 1 can be shifted to high speed traveling.

  On the other hand, when the swash plates 22a and 23a in the two axial piston motors 22 and 23 are simultaneously operated so as to reduce the inclination angle, both the axial piston motors 22 and 23 are simultaneously driven by the hydraulic pressure from one hydraulic pump 21. By being driven to rotate, the motor output shafts 26 of the axial piston motors 22 and 23 have a low rotational speed, so that the traveling work machine 1 can be shifted to a low speed.

  Then, by operating the swash plates 22a and 23a of the axial piston motors 22 and 23 at an arbitrary inclination angle, the motor output shaft 26 of the axial piston motors 22 and 23 is steplessly adjusted to an arbitrary rotational speed. Therefore, the traveling work machine 1 can be steplessly shifted to an arbitrary traveling speed between the high speed traveling and the low speed traveling.

  In this case, a lid plate 24 is detachably attached to the mission case 8 so as to close the extraction window 8b formed in the mission case 8, and the hydraulic pump 21 and the two axial pistons are attached to the lid plate 24. The motors 22 and 23 and their motor output shafts 26 are installed, and the lid plate 24 is provided with a hydraulic circuit for connecting the hydraulic pump 21 and the axial piston motors 22 and 23 to each other. By attaching and removing the cover plate 24 to and from the transmission case 8, the hydraulic pump 22, the two axial piston motors 22 and 23, and the hydraulic circuit therebetween can be assembled and disassembled to the transmission case 8.

It is a side view which shows the tractor to which embodiment of this invention is applied. It is a top view of FIG. It is a skeleton diagram of power transmission. It is a vertical front view which shows the detail of a hydraulic travel transmission mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Traveling work machine 2 Traveling machine body 3, 4 Wheel 5 Engine 8 Transmission case 8a Front surface of transmission case 8b Drawer window 20 Hydraulic traveling speed change mechanism 21 Hydraulic pump 21a Pump shaft 22, 23 Axial piston motor 22a, 23a Swash plate 24 Cover plate 26 Motor output shaft

Claims (3)

In a traveling working machine comprising a traveling machine body supported by traveling means such as wheels, an engine and a transmission case for transmitting the power of the engine to the traveling means,
The transmission case is provided with a hydraulic pump that is rotationally driven by the engine, and two swash plate type axial piston motors are connected in series to the power transmission part to the traveling means in the transmission case. A hydraulic circuit is provided between the axial piston motor and the hydraulic pump so that the hydraulic pressure from the discharge port of the hydraulic pump is supplied to both axial piston motors, and the hydraulic pressure from the discharge port of both axial piston motors is returned to the hydraulic pump. A hydraulic traveling transmission apparatus in a traveling working machine, characterized in that it is provided.   2. The lid according to claim 1, wherein a lid plate for closing the extraction window formed in the mission case is detachably attached to the mission case, and the hydraulic pump and both axials are provided on the surface of both sides of the lid body. A hydraulic travel transmission for a travel work machine, wherein one axial piston motor of the piston motors is mounted on the back side and the other axial piston motor is mounted on the back surface.   3. The hydraulic traveling transmission apparatus according to claim 2, wherein the hydraulic circuit is provided inside the lid plate.

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