JPH10299793A - Steering operation structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a transmission by shortening the lateral width of a transmission case through a process of arranging and overlapping a bearing and a cylinder chamber and shortening a steering shaft. SOLUTION: A steering operation structure, a side gear capable of freely switching power transmission from a driving gear to the traveling position on the lower side by being engaged and disengaged in relation to the driving gear in a transmission case is fitted on a steering shaft so as to be freely slid, a piston member 41 is arranged on the outer end of the side gear so as to face it, the side gear is slid into the case by an advancing motion of the piston member, a side clutch is operated so as to be disengaged, and a side brake is brake-operated by a further sliding movement. In this case, a cylinder chamber 41a for housing the piston member 41 so that it may be freely slide in the axial direction is provided on the outer periphery of a bearing 44 for supporting both outer ends of the steering shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering clutch for independently connecting and disconnecting power to left and right traveling drive shafts and a steering brake for applying a braking force to a disconnection side of power transmission. The present invention relates to a technology for disposing the steering shaft on a steering shaft in a case.

[0002]

2. Description of the Related Art Conventionally, a steering shaft has been mounted laterally in a transmission case, and a brake case has been fitted to a portion of the transmission case where the left and right ends of the steering shaft are supported by the transmission case. The steering piston is housed in the cylinder,
A pair of cylinders are slidably disposed on the left and right sides of the steering shaft, and one end of each of the cylinders is biased by a spring so as to contact the piston, and a clutch gear and a side gear are provided on the cylinder. A steering operation structure in which a piston is hydraulically advanced by providing a locking portion of a friction plate with a friction plate to cut off power transmission to the clutch gear and further advance to apply braking is known. is there. For example, the technique is disclosed in Japanese Utility Model Publication No. 6-41908.

[0003]

However, the prior art has the following problems. That is, since the piston member for sliding the side gear into the case is disposed between the side gear and the bearing, the steering shaft becomes longer, the transmission becomes larger, and the bearing case has Since the fixed-side friction plate of the side brake was locked, the shape was complicated and the manufacturing cost was high.
Further, the clutch gear is provided at one end of the side gear, and a locking portion for locking the rotating friction plate of the side brake is separately provided at the other end side, so that the manufacturing cost has been increased.

Further, the piston member is slid by hydraulic pressure, so that the side clutch is not turned on and the side clutch is turned off, that is, the side brake is not operated, and the side clutch is not operated. Extremely sophisticated technology is required to accurately appear in the "off" position only by adjusting the hydraulic pressure. The return spring that urges the side gear to the side clutch "on" position is located closer to the inside of the case of the steering shaft, and must be assembled to the steering shaft in the order of the return spring and the side gear. It had to be replaced due to wear and the like, and when inspecting, all had to be disassembled, which was time-consuming.

[0005]

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described. The power transmission from the drive gear by engaging and disengaging from the drive gear in the transmission case is performed. A piston member is arranged on the outer end side to oppose, the side gear is slid inward by the advance movement of the piston member, the side clutch is turned off, and the side brake is braked by further sliding. In the steering operation structure configured as described above, a cylinder chamber for accommodating a piston member slidably in the axial direction is provided on an outer periphery of a bearing that supports both outer ends of the steering shaft.

Further, the bearing case is held by bearing cases mounted on left and right side walls of the transmission case, and an outer peripheral portion of a bearing holding portion of the bearing case is recessed outside the case to form the cylinder chamber. A cylindrical portion recessed inward of the case is formed at a mounting surface portion of the bearing case of the transmission case, and a fixed-side friction plate of the side brake is non-rotatably locked to the cylindrical portion. . Further, a cylindrical body is slidably fitted on the steering shaft, and a substantially central portion of a tooth portion continuously engraved from one end side to the other end side on an outer peripheral surface of the cylindrical body is the side gear. On the other hand, one end side of the tooth portion is used as a clutch gear for a drive gear, and a rotation-side friction plate of a side brake is locked to the other end side so as not to rotate relatively. In the cylinder chamber, a drain oil passage is provided at a position corresponding to the side clutch disengagement of the piston member, and a pressure adjusting device is interposed in the drain oil passage. Further, the base end of the return spring for urging the side gear to the outside of the case to obtain an engagement state with the drive gear is provided. And the base end of the return spring is received by the locking portion of the steering shaft when the side gear is mounted on the steering shaft.

[0007]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 is a skeleton diagram of a traveling power transmission mechanism having a steering operation structure of the present invention, FIG. 2 is an upper rear cross-sectional view of a transmission case having a steering operation structure of the present invention, and FIG. 4 is a cross-sectional view of the lower rear part, FIG. 5 is a partial cross-sectional view and a hydraulic circuit diagram of the steering clutch brake in a straight running state, FIG. 6 is a diagram showing a gentle turning state with the side clutch “disengaged”, and FIG. FIG. 8 is a perspective view of a tubular body showing a sharp turning state with the side brake “ON”.

A transmission having a steering operation structure according to the present invention will be described with reference to FIGS. An HST-type transmission 2 is mounted on a transmission case 1. The HST-type transmission 2 has a pump shaft 3 protruding from one side of an HST case 5, and an input pulley 4 is fixed to the transmission case 2. The force is transmitted to the input pulley 4 via a V-belt. The rotation of the input pulley 4 drives the variable displacement hydraulic pump P housed in the HST case 5, and pressure oil from the hydraulic pump P is sent to the hydraulic motor M. At this time, by changing a shift arm (not shown), the angle of the swash plate of the hydraulic pump P is changed, and the discharge amount and the discharge direction are changed. This pressure oil drives the motor shaft 6 of the hydraulic motor M steplessly. A gear 7 is fixed on the motor shaft 6. The gear 7 meshes with a loose fitting gear 12 on an intermediate shaft 11 supported by a side case 10, and the gear 12 is fixed on an input shaft 13. The power shifted by the HST transmission 2 is transmitted into the transmission case 1 by meshing with the gear 14.

The transmission case 1 is formed in a left and right half-split type. The transmission case 1 includes an input shaft 13, an auxiliary transmission shaft 15, a steering shaft 16, a counter shaft 17, and a PTO shaft 1.
8 are mounted on the input shaft 13 in the transmission case 1 with fixed gears 20 and 21, a loosely fitted gear 28, and a spline hub 13a. The clutch slider 8 is spline-fitted slidably in the axial direction. The fixed gear 20 is always meshed with a loose fitting gear 22 on the auxiliary transmission shaft 15, and the fixed gear 21 is a loose fitting gear 23 on the auxiliary transmission shaft 15.
Is always engaged. The gear 22 always meshes with a gear 24 fixed on the counter shaft 17, and a gear 25 is further fixed on the counter shaft 17.
Always meshes with a gear 26 externally fitted on the PTO shaft 18 via a one-way clutch 29. A PTO pulley 27 is fixed to the PTO shaft 18 outside the transmission case 1 so that power from the gear 22 can be taken out via a one-way clutch 29 to drive the work machine.

A spline hub 15a is provided between the idle gear 22 and the idle gear 23 on the auxiliary transmission shaft 15, and a clutch slider 30 is spline-fitted slidably in the axial direction. The gear 22 and the gear 23 are formed with teeth 22a and 23a for the clutch slider 30. Further, a tooth portion 28a for the clutch slider 8 is formed on the loose fitting gear 28 on the input shaft 13. The clutch slider 8 and the clutch slider 30 are slid at the same time, and are connected to the gear 28 and the input shaft 13, or by connecting one of the gears 22 and 23 to the auxiliary transmission shaft 15, and Power is transmitted to the shaft 15. An output gear 31 is further engraved on the auxiliary transmission shaft 15, and a brake drum 32 is fixed outside the transmission case 1, and the parking brake is braked by rotating a brake arm 33.

A driving gear 3 is provided at a central portion of the steering shaft 16.
4, the output gear 31 on the auxiliary transmission shaft 15
Is engaged. Bosses 34L and 34R extending in the axial direction protrude from both side surfaces on the axial center side of the drive gear 34, and the outer peripheral sides of the inner peripheral surfaces of the bosses 34L and 34R are shown in FIG. As shown, the clutch gears 34a and 3
4a is engraved, and further, gaps 34b
Is provided.

On the steering shaft 16, cylinders 35L and 35R are provided so as to be relatively rotatable and axially slidable with a drive gear 34 interposed therebetween. As shown in FIG. 8, the cylindrical bodies 35L and 35R are formed by engraving continuous teeth from one end to the other end on the outer peripheral surface of the wide cylindrical body in the direction of the rotation axis, and then forming the teeth on one end thereof. A clutch gear 35a capable of meshing with the clutch gears 34a.
Further, a portion adjacent to the clutch gear 35a is scraped off from the root portion to provide a gap portion 35b. And
The wide tooth portion adjacent to the gap 35b is a side gear 35
c, and a locking portion 35d of the rotation-side friction plate 37 to be described later. On the other hand, the tooth portions on the other end side of the cylindrical bodies 35L and 35R are scraped off so as to be shorter than the tooth length of the locking portion 35d to form a mounting portion 35e of a pressing plate 39, which will be described later. Can be prevented from moving in the axial direction to one side by a step portion 35f between the locking portion 35d and the installation portion 35e.

The width of each of the gaps 34b and 35b in the axial direction is determined by the clutch gear 34a when the cylinders 35L and 35R move from the side clutch disengagement position to the side brake engagement position, as described later. The dimensions are set so that the clutch gear 35a is kept in the disengaged state.

The side gear 35 of the cylinder 35L / 35R
c is always meshed with the reduction gears 36L and 36R. The reduction gears 36L and 36R are fixed to inner ends of traveling drive shafts 19L and 19R supported at the lower part of the transmission case 1, and the traveling drive shafts 19L and 19R are connected to the transmission case 1 and the axle cases 47L and 47R via bearings. The driving sprocket 4 is supported on the outer ends of the traveling drive shafts 19L and 19R.
8L and 48R are fixedly provided to drive the crawler.

A rotary friction plate 37.3 for a multi-plate type side brake is provided on the locking portion 35d of the cylinder 35L / 35R.
Are locked so that they cannot rotate relative to each other. The friction plate 3
The fixed-side friction plates 38, 38,.
And a hollow cylindrical portion 1a which is recessed inwardly into a portion of the transmission case 1 which fixedly supports the bearing case 42 which supports both outer ends of the steering shaft 16. Is formed on the inner periphery of the cylindrical portion 1a.
Are locked so that they cannot rotate.

At the outer ends of the cylinders 35L and 35R, there are shown in FIG.
As shown in FIG. 7, the ring-shaped pressing plate 39 is locked, and the piston member 41 is connected via the thrust bearing 40.
Is in contact with The piston member 41 is formed in a ring shape. A cylinder case 41a concentric with the bearing 44 and having a concave shape is formed on the outer periphery of the bearing 44 in the bearing case 42, and the piston member 41 is fitted into the cylinder chamber so as to be slidable in the axial direction. Friction plate 37
. 38 ... are arranged to face each other. The bearing case 42 is fixed to left and right outer walls of the transmission case 1 via side oil passage plates 43.
A bearing 44 is held at the center of the steering shaft 16 and rotatably supports both end portions of the steering shaft 16.

On both sides of the steering shaft 16, there are provided reduced diameter portions 16b having a smaller diameter than the central portion thereof.
The return spring 53 is externally fitted on the upper surface b, and the inner end side of the return spring 53 is locked by the step portion of the reduced diameter portion 16b, and further, approximately half of the cylindrical bodies 35L and 35R are disposed on the outer periphery thereof.
Then, the retaining ring 52 is locked on the inner peripheral surface on the outer end side of the cylindrical bodies 35L and 35R, and the outer end of the return spring 53 is locked.
The cylinders 35L and 35R are urged so as to slide outward from the case, and the clutch gears 35a and 3 of the cylinders 35L and 35R are urged.
5a is meshed with the clutch gears 34a of the drive gear 34. The side brake is configured as described above.

The side oil passage plates 43L and 43R are provided with supply oil passages 45L and 45R and a drain oil passage 46. The supply oil passages 45L and 45R are connected to an oil supply port 60L of the cylinder chamber 41a of the bearing case 42. 60R and the output ports 50L and 50R of the steering switching valve 50 respectively communicate with each other, and the drain oil passages 46L and 46R are drained when the stroke of the piston member 41 is opened at a position corresponding to the "disengage" position of the side clutch. The ports 61L and 61R communicate with the tank port T, and a pressure regulating valve 51 is interposed between them. Also, on the primary side of the pressure regulating valve 51, check valves 100L and 100L permitting oil flow only from the oil discharge ports 61L and 61R toward the pressure regulating valve 51.
R is interposed.

The steering switching valve 50 is connected to a neutral (straight) position where the oil supply ports 60L and 60R of the side brake and the pump port of the hydraulic pump 54 are connected to the tank, and to the left and right oil supply ports 60L and 60R. And a three-position switching solenoid valve having an operation (turning) position for feeding oil. The pressure regulating valve 51 is linked with a steering lever 55 provided in the driver's seat, is urged toward the valve closing side by a spring 51a, and the side clutch “disengaged” position of the steering lever 55 is in its tilting position. Switch 5 for detecting
6L and 56R are provided, and the turning switches 56L and 56R are provided.
R is connected to the solenoid of the steering switching valve 50 via a controller (not shown).

In such a configuration, when the vehicle is traveling straight, as shown in FIG.
a and 34a are clutch gears 35a of cylindrical bodies 35L and 35R.
-The power shifted by the HST-type transmission 2 is transmitted to the traveling drive shafts 19L and 19R by meshing with 35a,
The right and left crawlers are driven simultaneously, and the aircraft runs straight.

When the steering lever 55 is tilted to the left or right one side, as shown in FIG. 6, the steering lever 55 turns on the turning switch 56L (56R), and one solenoid of the steering switching valve 50 is energized. To one of the operating positions. Then, pressure oil from the hydraulic pump 54 is guided from the output port 50L to the cylinder chamber 41a from the oil supply port 60L of the bearing case 42 via the oil supply passage 45L. Then, the piston member 41 is opposed to the return spring 53 and the cylinder 3
When 5L is pushed inward of the case, the clutch gear 35a is disengaged from the clutch gear 34a and enters the gap 34b. Here, when the stroke is performed to the position of the "side clutch disengagement" state, the pressure oil in the cylinder chamber 41a flows from the drain port 61L to the drain oil passage 46L and the check valve 10
0L, the oil is discharged into the transmission case 1 through the pressure adjustment valve 51, so that the piston member 41 is connected to the oil discharge port 61L.
And the aircraft turns slowly with a large turning radius.

When the steering lever 55 is further tilted therefrom, the pressure adjusting valve 51 is closed by the urging force of the spring 51a which increases in proportion to the tilt amount of the steering lever 55 as shown in FIG. The pressure oil in the cylinder chamber is no longer drained from the oil discharge port 61L, and the piston member 41 can slide to the stroke end of the cylinder chamber 41a. The hydraulic pressure in the cylinder chamber 41a is a spring 51a.
When the pressure becomes equal to or higher than the urging force equivalent pressure, the pressure regulating valve 51 is relieved and drained. At this time, the piston member 41 pushes the cylindrical body 35L inward of the case, and the clutch gears 34a
5a while maintaining the state of disengagement of 5a.
Presses the friction plates 37 and 38 to change from the "side clutch disengaged" state to the "side brake engaged" state.
The aircraft turns sharply from a large turning radius to a small turning radius.

[0023]

As described above, the present invention has the following advantages. That is, the power transmission from the drive gear by engaging and disengaging with the drive gear in the transmission case, the side gear that can be turned on and off to the lower traveling device is slidably fitted to the steering shaft, A piston member is arranged opposite to the outer end of the side gear, and the side gear is slid inward as the piston member moves forward, the side clutch is turned off, and the side brake is braked by further sliding. Since the cylinder chamber for accommodating the piston member slidably in the axial direction is provided on the outer periphery of the bearing supporting both outer ends of the steering shaft, the bearing and the cylinder chamber are arranged in an overlapping manner. As a result, the steering shaft can be shortened, the width of the transmission case can be reduced, and the transmission can be made compact.

Further, the bearing is held by bearing cases mounted on the left and right side walls of the transmission case, and an outer peripheral portion of a bearing holding portion of the bearing case is recessed outside the case to form the cylinder chamber. A cylindrical portion recessed inward of the case is formed on the mounting surface of the bearing case of the transmission case, and the fixed-side friction plate of the side brake is non-rotatably locked to the cylindrical portion. Can be simplified, and the production cost can be reduced.

A cylindrical body is slidably fitted on the steering shaft, and a substantially central portion of a tooth portion continuously engraved on the outer peripheral surface of the cylindrical body from one end to the other end thereof is provided. While using as the side gear, one end side of the tooth portion is used as a clutch gear for the drive gear, and the rotation side friction plate of the side brake is locked to the other end side so as to be relatively non-rotatable. Each part of the tooth portion that is engraved wide functions as a locking portion for the side gear, the clutch gear, and the rotating friction plate, and can be manufactured easily at low cost.

Further, since the drain oil passage is provided at a position corresponding to the side clutch disengagement of the piston member in the cylinder chamber, the "disengaged" state of the side clutch can be reliably exhibited. Since the pressure adjusting device is interposed, the "on" operation of the side brake can be obtained by operating to increase the pressure set value of the pressure adjusting device.

Further, the base end of the return spring for urging the side gear to the outside of the case to obtain an engagement state with the drive gear is provided in a state where substantially half of the return spring is locked by the locking portion of the side gear. Since the base end of the return spring is received by the locking portion of the steering shaft when the side gear is incorporated into the steering shaft, the return spring is mounted on the outer inner peripheral portion of the side gear. It is not necessary to use a special tool when assembling the steering shaft, the side gear can be assembled at a predetermined position of the steering shaft and at the same time it can be arranged in a projecting manner between the steering shaft and the side gear, Maintenance inspection can be performed very easily.

[Brief description of the drawings]

FIG. 1 is a skeleton diagram of a traveling power transmission mechanism having a steering operation structure of the present invention.

FIG. 2 is an upper rear cross-sectional view of a transmission case including the steering operation structure of the present invention.

FIG. 3 is a plan sectional view of the same.

FIG. 4 is a cross-sectional view of the lower rear surface in the same manner.

FIG. 5 is a partial sectional view and a hydraulic circuit diagram of a steering clutch brake in a straight traveling state.

FIG. 6 is a view showing a gentle turning state with the side clutch “disengaged”.

FIG. 7 is a view showing a sudden turning state when the side brake is turned on.

FIG. 8 is a perspective view of a cylindrical body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission case 1a Cylindrical part 16 Steering axis 34 Drive gear 35L / 35R Cylindrical body 35a Clutch gear 35c Side gear 35d Locking part 37/38 Friction plate 41 Piston member 41a Cylinder chamber 42 Bearing case 44 Bearing 46L / 46R Drain oil passage 50 Steering switching valve 51 Pressure adjusting valve 53 Return spring

Claims (5)

[Claims] 1. A side gear which is engaged with and disengaged from a drive gear in a transmission case to transmit and receive power from the drive gear to a traveling device on a lower side, and which is slidably fitted to a steering shaft. At the same time, a piston member is arranged on the outer end side of the side gear to oppose it, and the side gear is slid inward by the advance movement of the piston member to “disengage” the side clutch.
In the steering operation structure configured to operate and brake the side brake by further sliding, a piston member is axially slidably received on an outer periphery of a bearing supporting both outer ends of the steering shaft. Steering operation structure characterized by having a cylinder chamber. 2. The cylinder case is formed by holding the bearing in bearing cases mounted on left and right side walls of the transmission case, and recessing an outer peripheral portion of a bearing holding portion of the bearing case to the outside of the case. A cylindrical portion recessed inward of the case is formed at a mounting surface portion of the bearing case of the transmission case, and a fixed-side friction plate of the side brake is non-rotatably locked to the cylindrical portion. The steering operation structure according to claim 1, wherein 3. A substantially central portion of a tooth portion having a cylindrical body slidably fitted on the steering shaft and continuously engraved on the outer peripheral surface of the cylindrical body from one end to the other end thereof. 2. The steering device according to claim 1, wherein one end of the tooth portion is used as a clutch gear for a drive gear, and a rotating friction plate of a side brake is locked to the other end so as to be relatively non-rotatable. Direction operation structure. 4. A drain oil passage is provided in the cylinder chamber at a position corresponding to a side clutch disengagement of a piston member,
A pressure adjusting device is interposed in the drain oil passage.
The described steering operation structure. 5. A state in which the base end of a return spring for urging the side gear to the outside of the case to obtain an engagement state with the drive gear, substantially half of which is locked by a locking portion of the side gear. Wherein the base end of the return spring is received by the locking portion of the steering shaft when the side gear is mounted on the steering shaft. 2. The steering operation structure according to 1.