JPH10252638A - Hydraulic drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rotate a hub at rotating speed of a wide range while being small and inexpensive by selectively meshing a first driving gear and a first driven gear or a second driving gear and a second driven gear with each other by integrally moving the driving gears in the shaft direction. SOLUTION: A quantity of pressure oil supplied to a hydraulic motor 11 is controlled, and when a tilting condition of a swash plate 31 of the hydraulic motor 11 is changed in two stages, rotating speed (rotating speed of a hub 48) of an output shaft 16 can be set to a prescribed range, but a first driving gear 63 and a second driving gears 64 are integrally moved in the shaft direction by a piston 77 and a spring 80, and when the first driving gear 63 and a first driven gear 75 or a second driving gear 64 and a second driven gear 76 are selectively meshed with each other, the rotating speed of the output shaft 16 is changed further in two stages in the middle of being transmitted to the hub 48, and a rotating speed range of the hub 48 is expanded further thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drive system having a swash plate type hydraulic motor and an eccentric differential reducer.

[0002]

2. Description of the Related Art In recent years, swash plate type hydraulic motors, eccentric differential reduction gears, output shafts of these hydraulic motors and eccentric differential reduction gears have been used as driving hydraulic drive devices for civil engineering construction machines such as hydraulic excavators and wheel loaders. Each is attached to the crankshaft of the machine and rotates by meshing with each other, for example
Those having a pair of spur gears that reduce speed to 1/3 have come to be used frequently. This is because the swash plate type hydraulic motor is inexpensive and can control a wide range of revolutions by controlling the flow rate of supply hydraulic pressure, and the eccentric differential reducer performs high ratio deceleration while maintaining high mechanical strength. Is the result of the evaluation.

Recently, it has been considered to use such a hydraulic drive device as a traveling drive device such as an asphalt finisher that requires a wider range of speed control. Could not. For this reason, the swash plate of the swash plate type hydraulic motor can be tilted between a plurality of tilt positions, whereby the rotation speed of the output shaft of the hydraulic motor can be changed to a plurality of stages to thereby reduce the speed range. It was proposed to spread.

[0004]

If the tilt angle of the swash plate can be changed as described above, the speed range can be widened to some extent while the production cost is suppressed, but the speed range is not yet sufficient for use in asphalt finishers and the like. It was not enough.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydraulic drive device capable of rotating a hub at a wide range of rotation speed while being small and inexpensive.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a swash plate type hydraulic motor having an output shaft whose rotational speed changes to a plurality of stages by changing the tilt position of the swash plate to a plurality of positions, An eccentric differential reducer that reduces the rotation input to the parallel crankshaft by a pinion that eccentrically rotates and outputs the reduced rotation to a hub, and is interposed between an output shaft of the hydraulic motor and a crankshaft of the eccentric differential reducer. Transmission means for transmitting the rotation of the output shaft to the crankshaft,
The transmission means is supported on the output shaft of the hydraulic motor so as to be movable in the axial direction and to rotate integrally with the output shaft, and is attached to the first and second drive gears having different pitch circle diameters and the crankshaft. First and second driven gears having different pitch circle diameters and the first and second driven gears or the second driven gear by moving the first and second driving gears integrally in the axial direction; This can be achieved by having a moving mechanism for selectively meshing the second driven gears with each other.

When pressure oil is supplied to the hydraulic motor and the output shaft rotates, the rotation of the output shaft is transmitted to the crankshaft of the eccentric differential reducer via the transmission means to rotate the crankshaft. At this time, the rotation of the crankshaft is reduced by the eccentrically rotating pinion and output to the hub. Here, while controlling the amount of pressure oil supplied to the hydraulic motor and changing the tilt position of the swash plate of the hydraulic motor to a plurality of positions, the rotational speed of the output shaft (the rotational speed of the hub) can be reduced to a predetermined value. Can be a wide range. At this time, the first and second driving gears are integrally moved in the axial direction by the moving mechanism, and the first driving gear and the first driven gear mesh with each other, or
If the drive gear and the second driven gear mesh with each other, the rotation speed of the output shaft is changed in two stages while being transmitted to the hub, whereby the rotation speed range of the hub is further widened. For this reason, the present hydraulic drive device can be used as a travel drive device such as an asphalt finisher that requires a wide range of speed control.
Since it is only necessary to add two gears and a moving mechanism, the manufacturing cost is low and the size can be reduced.

Further, according to the second aspect of the present invention, the piston is housed in the eccentric differential reducer, and the entire hydraulic drive device can be reduced in size.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 11 denotes a swash plate type hydraulic motor mounted on a traveling frame of, for example, an asphalt finisher. The hydraulic motor 11 includes a case body 13 having a storage chamber 12 formed therein, and a A side plate 14 fixed to one end and closing the other end opening of the storage chamber 12 to form a closed space.
The side plate 14 constitutes a casing 15 as a whole. 16
Is an output shaft whose other side is inserted into the storage chamber 12,
The output shaft 16 is rotatably supported by the side plate 14 and the case body 13 via a bearing 17. One side of the output shaft 16 projects from the case body 13 toward one side.

Reference numeral 21 denotes a cylindrical cylinder block housed in the housing chamber 12, into which the other end of the output shaft 16 is inserted and connected by a spline. The cylinder block 21 is an output shaft
16 and can rotate together. Reference numeral 22 denotes a plurality of cylinder holes formed on one end surface of the cylinder block 21 and extending in the axial direction. Plungers 23 are slidably inserted into the cylinder holes 22, respectively. The shoes 25 are connected via ball joints 24, respectively. 27 is the cylinder block 21 and side plate 14
The timing plate 27 has two arc-shaped holes 28 spaced apart in the circumferential direction.
The cylinder holes 22 are connected to the arc holes 28 one after another by rotation of the cylinder block 21. 29 is the same number of supply and discharge passages as the arc-shaped holes 28 formed in the side plate 14,
One of the supply / discharge passages 29 communicates with one arc-shaped hole 28, and the other supply / discharge passage 29 communicates with the other arc-shaped hole 28. These supply / discharge passages 29 are connected to a pump and a tank via a switching valve (not shown). When the switching valve is switched, one of them becomes the supply side and the other becomes the discharge side.

Reference numeral 31 denotes a substantially ring-shaped swash plate housed in the housing chamber 12 of the casing 15, and the inside of the swash plate 31 is provided with the output shaft.
16 are penetrating. The other end of the swash plate 31 facing the cylinder block 21 has an inclined surface 32 that is inclined with respect to a plane perpendicular to the rotation axis of the output shaft 16, and the shoe 25 slides on the inclined surface 32. ing. The back surface (one end surface opposite to the inclined surface 32) 33 of the swash plate 31 facing the inner surface of one end of the storage chamber 12 has a first flat portion 33a located on the thick portion side and a first flat portion 33a located on the thin portion side. The second flat portion 33b is inclined at a predetermined small angle with respect to the first flat portion 33a. The swash plate 31 is connected to the first and second swash plates.
The second flat portion 33b and the storage chamber 12 are centered on a fulcrum member (not shown) arranged on the boundary between the flat portions 33a and 33b.
The first tilt position (the position shown in FIG. 1) in which the inner surface of one end of the storage chamber 12 is in surface contact with the inner surface of the first flat portion 33a. Position can be tilted between two tilt positions. 35 is a substantially ring-shaped retainer plate engaged with all the shoes 25, and 36 is a spherical contact with the inner periphery of the retainer plate 35, and is fitted to the outside of the output shaft 16 and connected by a spline connection. The ball 37 is a spring that applies a biasing force toward the one side via the transmission rod 38 to the thrust ball 36.

A cylinder hole 41 is formed in the inner surface of one end of the case body 13 facing the second flat portion 33b of the swash plate 31, and a pressing piston 42 is slidably inserted into the cylinder hole 41. 43 is a passage formed in the casing 15,
One end of this passage 43 is connected to a hydraulic source (not shown),
The other end is connected to the cylinder hole 41. When the pressure oil is supplied to the cylinder hole 41 through the passage 43,
The pressing piston 42 presses the second flat portion 33b of the swash plate 31 to tilt the swash plate 31 from the first tilt position to the second tilt position, while the supply of the pressure oil to the cylinder hole 41 is stopped. Then, the swash plate 31 is tilted from the second tilt position to the first tilt position by the pressing force from the plunger 23. Thus, the stroke of the plunger 23 in the cylinder block 21 is changed in two stages, and the rotation speed of the cylinder block 21 and the output shaft 16 is changed in two stages.

Reference numeral 47 denotes an eccentric differential reducer attached to one end of the hydraulic motor 11. The eccentric differential reducer 47 has a substantially cylindrical hub 48. The hub 48 is, for example, an asphalt finisher. Drive wheels. This hub 48
At the central portion in the axial direction at the inner periphery of the cylindrical member, a large number of cylindrical internal tooth pins 49 are inserted by almost half. ing. Two disk-shaped pinions 50 are housed in the hub 48, and the inner teeth pins are provided on the outer periphery of each pinion 50.
The external teeth 51 are formed so as to mesh with the internal teeth 49 and have a slightly smaller number of teeth than the number of the internal teeth pins 49. Also, each pinion 50
Has a plurality of through holes 52 and a plurality of through holes
53 are formed respectively. 55 is a fixed carrier housed in the hub 48, and this fixed carrier 55 is a pinion
A disk-shaped end plate 56 arranged on one side of 50 and one end plate
A connecting body 58 is connected to the motor body 56 via a plurality of bolts 57, and the other end is integrally connected to the case body 13 of the hydraulic motor 11. The connecting bodies 58 extend in the axial direction and are loosely fitted in the loose fitting holes 52 of the pinion 50.

Reference numerals 61 and 62 denote through holes formed in the center of the eccentric differential reducer 47, more specifically, on the central axes of the pinion 50 and the end plate 56, respectively. One side of the output shaft 16 of the hydraulic motor 11 is loosely fitted. 63,
Reference numeral 64 denotes first and second drive gears provided at one end of the output shaft 16, and the first and second drive gears 63 and 64 are spline-coupled to the output shaft 16. Are supported so that they can move in the axial direction and can rotate integrally with the output shaft 16. The first and second drive gears 63 and 64 are connected to the output shaft 16 such that their external teeth and spline teeth have the same phase. In addition, these first and second
The drive gears 63 and 64 are separated from each other in the axial direction by a spacer 65 interposed therebetween by a distance slightly larger than the thickness of a first driven gear 75 described later, and have different pitch circle diameters (in this embodiment, The pitch circle diameter of the second drive gear 64 is larger than the pitch circle diameter of the first drive gear 63).

Reference numeral 69 denotes a plurality of crankshafts parallel to the output shaft 16, and both ends of the crankshafts 69
And end plates 56 rotatably supported by rolling bearings 70, respectively. Each crankshaft 69 has two eccentric portions 71 eccentric in the opposite direction from the center axis of the crankshaft 69 at the center portion in the axial direction. These eccentric portions 71 are needle roller bearings in shaft holes 53 of the pinion 50. Each is inserted with 72 interposed. First and second driven gears 75 and 76 are attached to one end of each crankshaft 69 protruding from the end plate 56 by spline coupling in a state where they are in close contact with each other. These first and second driven gears 75 and 76 are The pitch circle diameters are different from each other (in this embodiment, the pitch circle diameter of the first driven gear 75 is larger than the pitch circle diameter of the second driven gear 76). When the first and second drive gears 63 and 64 move integrally in the axial direction, the first drive gear 63 and the first driven gear 75 or the second drive gear 64 and the second driven gear 76 are connected. At this time, if the first drive gear 63 and the first driven gear 75 are meshed with each other, the rotation of the output shaft 16 becomes
For example, when the speed is reduced to 1/3 and transmitted to the crankshaft 69, while the second drive gear 64 and the second driven gear 76 are meshed with each other, the rotation of the output shaft 16 is equal, that is, without being reduced. The power is transmitted to the crankshaft 69. Here, the first and second
The driven gears 75 and 76 are also connected to the crankshaft 69 such that their external teeth and spline teeth have the same phase, so that the above-described meshing switching is performed smoothly.

Reference numeral 77 denotes a through hole 62 of the output shaft 16 and the end plate 56.
A piston disposed between the inner surface and the piston.
77 is supported on the output shaft 16 and the end plate 56 so as to be movable in the axial direction. When the piston 77 is arranged at such a position, the piston 77 is housed in the eccentric differential reducer 47, and the entire hydraulic drive device can be reduced in size. Reference numeral 78 denotes a passage formed in the casing 15 and the fixed carrier 55.One end of the passage 78 is connected to a hydraulic pressure source via a switching valve (not shown), and the other end is between the piston 77 and the end plate 56. Is connected to a cylinder chamber 79 formed at the bottom. Reference numeral 80 denotes a spring interposed between a spring receiver 81 attached to one end of the output shaft 16 and the second drive gear 64. The spring 80 moves the first and second drive gears 63 and 64 to the other side. Energize toward. When the pressure oil is guided to the cylinder chamber 79 through the passage 78, the piston 77 is pressed by the pressure oil and moves in one axial direction.
The first and second drive gears 63 and 64 are moved by the spring 80
When the pressure oil is no longer guided to the cylinder chamber 79 when the first drive gear 63 and the first driven gear 75 mesh with each other while moving in one axial direction while compressing the The urging force causes the piston 77 to move in the other axial direction, and the movement of the piston 77 causes the first and second drive gears 63 and 64 to move in the other axial direction, thereby causing the second drive gear 64 and the second driven gear 76 to move.
And bite. The piston 77, the passage 78, and the spring 80 described above as a whole move the first and second drive gears 63 and 64 integrally in the axial direction, thereby forming the first drive gear 63 and the first drive gear 63.
Driven gears 75 or second drive gear 64, second driven gear
The first and second driving gears 63 and 64, the first and second driven gears 75 and 76, and the moving mechanism 82 as a whole comprise the hydraulic motor 11 Between the output shaft 16 and the crankshaft 69 of the eccentric differential reducer 47, and constitutes transmission means 83 for transmitting the rotation of the output shaft 16 to the crankshaft 69. 84 is the hub 48 and casing 1
5, a bearing interposed between the fixed carrier 55 and the bearing for rotatably supporting the hub 48 on the casing 15 and the fixed carrier 55; 85 is interposed between the hub 48 and the casing 15, A sealing member 86 for sealing is fixed to one end of the hub 48 and is a cover for closing the one end opening of the hub 48.

Next, the operation of the embodiment of the present invention will be described. When the pressure oil is supplied to the cylinder hole 22 of the cylinder block 21 through the one supply / discharge passage 29 and the arc-shaped hole 28,
The plunger 23 in the cylinder hole 22 projects toward the swash plate 31 and presses the inclined surface 32.At this time, since the tip of the plunger 23 is engaged with the inclined surface 32 via the shoe 25,
The circumferential component of the pressing force acts on the plunger 23, whereby the plunger 23 and the shoe 25 slide on the inclined surface 32 from the thick part side to the thin part side.
3. The cylinder block 21 and the output shaft 16 rotate integrally. Due to the rotation of the cylinder block 21, the plunger 23 in the cylinder hole 22 communicating with the other arc-shaped hole 28 becomes
In order to move from the thin portion side to the thick portion side on the inclined surface 32 of the swash plate 31, the inclined surface 32 is gradually pushed into the cylinder hole 22 and the pressure oil in the cylinder hole 22 is discharged to the other side. It discharges through the arcuate hole 28 and the supply / discharge passage 29. At this time, the rotation of the output shaft 16 is input to the crankshaft 69 via the transmission means 83, and rotates each crankshaft 69 around the central axis. As a result, the eccentric portion 71 of the crankshaft 69 eccentrically rotates in the shaft hole 53 of the pinion 50 to cause the pinion 50 to eccentrically revolve, but the number of the external teeth 51 is smaller than the number of the internal tooth pins 49 as described above. Since it is slightly less, the hub 48 is greatly decelerated by the eccentric orbital motion of the pinion 50 and rotates at a low speed.

Here, when it is desired to rotate the hub 48 at the minimum rotational speed, the amount of pressure oil supplied to the cylinder hole 22 of the hydraulic motor 11 is minimized and the pressure applied to the cylinder hole 41 through the passage 43 is reduced. Stop oil supply. As a result, the swash plate 31 is tilted to the first tilt position by the pressing force from the plunger 23, and the stroke of the plunger 23 is lengthened.
21, the rotation speed of the output shaft 16 is the lowest. At this time,
The pressurized oil is supplied to the cylinder chamber 79 through the passage 78, and the piston 77, the first and second drive gears 63 and 64 are moved in one axial direction to mesh the first drive gear 63 and the first driven gear 75 with each other. The rotation of the output shaft 16 is further reduced by the first drive and driven gears 63 and 75, and is reduced to 1/3 here. As a result, the hub 48 rotates at the minimum rotational speed.

On the other hand, when it is desired to rotate the hub 48 at the maximum rotational speed, the amount of pressure oil supplied to the cylinder hole 22 of the hydraulic motor 11 is maximized, and
Supply pressure oil to 41. As a result, the swash plate 31 is
The plunger 23 is tilted to the second tilt position by the projection of
The stroke of the cylinder block 21 and the rotation speed of the output shaft 16 are maximized in combination with the supply of the maximum amount of pressure oil. At this time, since the supply of the pressure oil from the passage 78 to the cylinder chamber 79 is stopped, the piston 7
7, the first and second drive gears 63 and 64 move in the other axial direction by the urging force of the spring 80, and the second drive gear 64 and the second driven gear 76 mesh with each other.
Since the hubs 64 and 76 transmit the rotation at a constant speed, that is, without deceleration, the hub 48 rotates at the maximum rotation speed.

As described above, by controlling the amount of pressure oil supplied to the hydraulic motor 11 and changing the tilt position of the swash plate 31 of the hydraulic motor 11 in two stages, the rotation speed of the output shaft 16 ( The number of rotations of the hub 48) can be within a predetermined range. However, as in this embodiment, the first and second drive gears 63 and 64 are integrally moved in the axial direction by the piston 77 and the spring 80, The first drive gear 63 and the first driven gear 75 or the second
If the drive gear 64 and the second driven gear 76 are selectively meshed with each other, the rotation speed of the output shaft 16 is further shifted in two stages while being transmitted to the hub 48, whereby the hub
The rotation speed range of 48 is further expanded. From this, the present hydraulic drive device can be used as a travel drive device such as an asphalt finisher that requires a wide range of speed control, and at this time, two gears, specifically, the second drive,
Since it is only necessary to add the driven gears 64 and 76 and the moving mechanism 82, the manufacturing cost is low and the size can be reduced.

Here, for example, a normal tilt angle two-step change type swash plate type hydraulic motor having a minimum rotation speed of 35 rpm and a maximum rotation speed of 3000 rpm and a normal eccentric differential having a reduction ratio of 1/50 In the case of a hydraulic drive device using a reduction gear, if the transmission means is constituted by a gear train having a reduction ratio of 1/3 as in the prior art,
The rotation speed of the hub is at least 0.23 rpm and up to 20 rpm, but in the case of asphalt finishers etc., it is usually 0.3 rpm to 60 rpm.
A speed range of rpm is required and cannot be used as is. However, as described above, if the second drive gear 64 and the second driven gear 76 can be engaged with each other as necessary to transmit the rotation at an equal ratio, the maximum rotation speed of the hub can be reduced to 60 rpm. The speed can be increased (the range of the number of rotations can be increased), and the present invention can be sufficiently applied to an asphalt finisher or the like.

In the above-described embodiment, the swash plate 31 is used.
The rotation speed of the output shaft 16 is changed to two stages by changing the tilt angle of the rotation shaft to two stages, but may be changed to three stages in the present invention. Further, in the above-described embodiment, the first and second drive gears 63 and 64 are
In the present invention, the first and second drive gears are connected to the piston and the pressure is alternately applied to both end faces of the piston. The first and second driving gears may be moved in the axial direction only by the piston by guiding the oil.

[0023]

As described above, according to the present invention, the hub can be rotated at a wide range of rotation speed while being small and inexpensive.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 11 ... swash plate type hydraulic motor 16 ... output shaft 31 ... swash plate 47 ... eccentric differential reducer 48 ... hub 50 ... pinion 62 ... through hole 63 ... first drive gear 64 ... second drive gear 69 ... crankshaft 75 ... 1 driven gear 76 ... second driven gear 77 ... piston 78 ... passage 82 ... moving mechanism 83 ... transmission means

Claims (2)

[Claims] A swash plate type hydraulic motor having an output shaft whose rotation speed changes in a plurality of stages by changing the tilt position of the swash plate to a plurality of stages, and a rotation input to a crankshaft parallel to the output shaft. An eccentric differential reducer that decelerates and outputs to a hub by an eccentric rotating pinion, and is interposed between an output shaft of the hydraulic motor and a crankshaft of the eccentric differential reducer, and rotates the output shaft to a crankshaft. And a transmission means for transmitting the transmission means, wherein the transmission means is axially movable on an output shaft of the hydraulic motor and supported so as to rotate integrally with the output shaft, and the first transmission means has a different pitch circle diameter from each other. , A second drive gear, first and second driven gears attached to the crankshaft and having different pitch circle diameters, and a first drive by moving the first and second drive gears integrally in the axial direction. gear,
A hydraulic drive device comprising: a moving mechanism that selectively meshes the first driven gears or the second drive gear and the second driven gear. 2. A through hole is formed in a central portion of the eccentric differential reducer, an output shaft of a hydraulic motor is loosely fitted in the through hole, and an output shaft and an inner surface of the through hole are used as the moving mechanism. A piston which is disposed between the pistons and which is movable in the axial direction of the output shaft, and a passage which guides the hydraulic oil to the pistons to move the pistons in the axial direction to move the first and second drive gears. Item 2. The hydraulic drive device according to Item 1.