JP3727135B2 - Hydraulic drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic drive device having a swash plate type hydraulic motor and an eccentric differential reduction gear.
[0002]
[Prior art]
In recent years, as hydraulic drive devices for civil engineering construction machines such as hydraulic excavators and wheel loaders, there are swash plate hydraulic motors, eccentric differential reducers, output shafts of these hydraulic motors, and crank shafts of eccentric differential reducers. Those equipped with a pair of spur gears that are respectively attached and meshed with each other to reduce the rotation to 1/3, for example, have come to be used frequently. This is because the swash plate hydraulic motor is inexpensive and can control a wide range of rotation speeds by controlling the flow rate of the supplied hydraulic pressure, and the eccentric differential reducer performs high ratio deceleration while maintaining high mechanical strength. This is the result of evaluation.
[0003]
Recently, it has been studied 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, but the current speed range cannot be used narrowly. It was. For this reason, the swash plate of the swash plate type hydraulic motor can be tilted between a plurality of tilt positions, whereby the speed range can be changed by changing the rotation speed of the output shaft of the hydraulic motor to a plurality of stages. Suggested to spread.
[0004]
[Problems to be solved by the invention]
If the tilt angle of the swash plate can be changed in this way, the speed range can be widened to some extent while suppressing the manufacturing cost, but the speed range has not yet been sufficient for use in asphalt finishers and the like.
[0005]
It is an object of the present invention to provide a hydraulic drive device that can rotate a hub at a wide range of rotation speeds while being small and inexpensive.
[0006]
[Means for Solving the Problems]
The purpose of this is to provide a swash plate type hydraulic motor having an output shaft whose rotational speed changes in a plurality of stages by changing the tilt position of the swash plate into a plurality of stages, and a rotation input to a crankshaft parallel to the output shaft. An eccentric differential reducer that decelerates the output by a pinion that rotates eccentrically and outputs it to the hub, and is interposed between the output shaft of the hydraulic motor and the crankshaft of the eccentric differential reducer. The transmission means includes a transmission means for transmitting to the output shaft of the hydraulic motor. 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. The first and second driven gears, the first and second driven gears that are attached to the crankshaft and have different pitch circle diameters, and the first and second drive gears are integrally moved in the axial direction. Drive gear, 1st driven tooth Or between the second drive gear, it can be accomplished by having a moving mechanism for selectively engaging the second driven gears.
[0007]
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 reduction gear via the transmission means to rotate the crankshaft. The rotation of the crankshaft is decelerated by the eccentric pinion and output to the hub. Here, if the amount of pressure oil supplied to the hydraulic motor is controlled and the tilt position of the swash plate of the hydraulic motor is changed to a plurality of positions, the rotational speed of the output shaft (the rotational speed of the hub) is set to a predetermined value. Can be a wide range. At this time, the first and second drive gears are integrally moved in the axial direction by the moving mechanism, and the first drive gear and the first driven gear are engaged with each other, or the second drive gear and the second driven gear are engaged with each other. If matched, the rotational speed of the output shaft is shifted in two stages while being transmitted to the hub, thereby further expanding the rotational speed range of the hub. For this reason, the 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 only two gears and a moving mechanism need to be added. Costs can be reduced and downsizing can be achieved.
[0008]
According to the second aspect of the present invention, the piston is accommodated in the eccentric differential reduction gear, and the entire hydraulic drive device can be reduced in size.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 11 denotes a swash plate type hydraulic motor attached to a traveling frame of, for example, an asphalt finisher. The hydraulic motor 11 includes a case main body 13 in which a storage chamber 12 is formed, and a case main body 13. The side plate 14 is fixed to the end and closes the other end opening of the storage chamber 12 to form a sealed space. The case body 13 and the side plate 14 constitute a casing 15 as a whole. Reference numeral 16 denotes an output shaft whose other side portion is inserted into the storage chamber 12, and this 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 protrudes from the case body 13 toward one side.
[0010]
21 is a cylindrical cylinder block stored in the storage chamber 12, and the other end of the output shaft 16 is inserted into the cylinder block 21 and connected by a spline. As a result, the cylinder block 21 can rotate integrally with the output shaft 16. A plurality of cylinder holes 22 are formed on one end surface of the cylinder block 21 and extend in the axial direction. Plungers 23 are slidably inserted into the cylinder holes 22, respectively. The shoes 25 are connected to each other through the ball joint 24. Reference numeral 27 denotes a timing plate interposed between the cylinder block 21 and the side plate 14, and two arc-shaped holes 28 separated in the circumferential direction are formed in the timing plate 27. The holes 22 are connected one after another as the cylinder block 21 rotates. 29 is the same number of supply / discharge passages as the arc-shaped holes 28 formed in the side plate 14, and one of the supply / discharge passages 29 of these supply / discharge passages 29 is in one arc-shaped hole 28 and the other supply / discharge passage 29 is It communicates with the other arcuate hole 28. Further, 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 the supply / discharge passages 29 becomes the supply side and the rest becomes the discharge side.
[0011]
31 is a substantially ring-shaped swash plate stored in the storage chamber 12 of the casing 15, and the output shaft 16 passes through the swash plate 31. The swash plate 31 has an inclined surface 32 that is inclined with respect to a plane perpendicular to the rotation axis of the output shaft 16 at the other end facing the cylinder block 21, and the shoe 25 is in sliding contact with the inclined surface 32. ing. In addition, the rear surface (one end surface opposite to the inclined surface 32) 33 of the swash plate 31 facing the inner surface at one end of the storage chamber 12 is positioned at the first flat portion 33a located on the thick portion side and 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 centered on a fulcrum member (not shown) disposed on the boundary between the first and second flat portions 33a and 33b, and the second flat portion 33b and the inner surface of one end of the storage chamber 12. 2 of the first tilt position (position shown in FIG. 1) in which the first flat portion 33a is in surface contact and the second tilt position in which the first flat portion 33a and one inner surface of the storage chamber 12 are in surface contact. It is possible to tilt between two tilt positions. 35 is a substantially ring-shaped retainer plate engaged with all the shoes 25, 36 is a spherical contact with the inner periphery of the retainer plate 35, and is a thrust fitted outside the output shaft 16 and connected by spline coupling. A ball 37 is a spring that applies an urging force directed to one side via the transmission rod 38 to the thrust ball 36.
[0012]
A cylinder hole 41 is formed in the inner surface of one end of the case main 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. Reference numeral 43 denotes a passage formed in the casing 15. One end of the passage 43 is connected to a hydraulic pressure source (not shown), and the other end is connected to the cylinder hole 41. When 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 move the swash plate 31 from the first tilt position to the second tilt position. When the supply of pressure oil to the cylinder hole 41 is stopped, the swash plate 31 is tilted from the second tilt position to the first tilt position by the pressing force from the plunger 23. As a result, the stroke of the plunger 23 in the cylinder block 21 is changed to two stages, and the rotational speeds of the cylinder block 21 and the output shaft 16 are changed to two stages.
[0013]
47 is an eccentric differential speed reducer attached to one end of the hydraulic motor 11, and this eccentric differential speed reducer 47 has a substantially cylindrical hub 48, which is, for example, a driving wheel of an asphalt finisher. It is connected to. In the inner periphery of the hub 48, a large number of cylindrical internal pins 49 are inserted into the central portion in the axial direction, and these internal teeth pins 49 extend in the axial direction and are equidistant from each other in the circumferential direction. Are arranged. In the hub 48, two disk-shaped pinions 50 are accommodated. The outer periphery of each pinion 50 meshes with the internal tooth pins 49 and has a number of teeth slightly smaller than the number of the internal tooth pins 49. Teeth 51 are formed. Each pinion 50 is formed with a plurality of penetrating loose-fitting holes 52 and a plurality of penetrating shaft holes 53, respectively. Reference numeral 55 denotes a fixed carrier housed in the hub 48. The fixed carrier 55 includes a disk-shaped end plate 56 disposed on one side of the pinion 50, and one end of the end plate 56 via a plurality of bolts 57. And the other end is integrally connected to the case body 13 of the hydraulic motor 11. These coupling bodies 58 extend in the axial direction and are loosely fitted in the loose fitting holes 52 of the pinion 50.
[0014]
61 and 62 are through holes formed in the central portion of the eccentric differential reduction gear 47, more specifically, on the central axes of the pinion 50 and the end plate 56, respectively. The through holes 61 and 62 include the hydraulic motor 11 One side of the output shaft 16 is loosely fitted. Reference numerals 63 and 64 denote first and second drive gears provided at one end of the output shaft 16, and these first and second drive gears 63 and 64 are spline-coupled to the output shaft 16 so that the output is achieved. The shaft 16 is supported so as to be movable in the axial direction and to rotate integrally with the output shaft 16. The first and second drive gears 63 and 64 are coupled to the output shaft 16 so that the external teeth thereof and the spline teeth have the same phase. The first and second drive gears 63 and 64 are separated by a spacer 65 interposed therebetween in the axial direction by a distance slightly larger than the thickness of the first driven gear 75 described later, and the pitch circle diameters are different from each other. (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).
[0015]
Reference numeral 69 denotes a plurality of crankshafts parallel to the output shaft 16, and both ends of the crankshafts 69 are rotatably supported by the case main body 13 and the end plate 56 via rolling bearings 70, respectively. Each crankshaft 69 has two eccentric portions 71 which are eccentric in the opposite direction from the central axis of the crankshaft 69 at the center in the axial direction, and these eccentric portions 71 are needle roller bearings in the shaft hole 53 of the pinion 50. Each is inserted with 72 interposed. First and second driven gears 75 and 76 are attached to one end portion of each crankshaft 69 projecting from the end plate 56 by spline connection, and these first and second driven gears 75 and 76 are attached to each other. 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 together 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 communicate with each other. At this time, if the first drive gear 63 and the first driven gear 75 are engaged with each other, the rotation of the output shaft 16 is reduced to 1/3 and transmitted to the crankshaft 69, for example. On the other hand, when the second drive gear 64 and the second driven gear 76 are engaged with each other, the rotation of the output shaft 16 is transmitted to the crankshaft 69 without being decelerated, that is, without being decelerated. Here, the first and second driven gears 75 and 76 are also coupled to the crankshaft 69 so that the external teeth thereof and the spline teeth have the same phase. Is called.
[0016]
77 is a piston disposed between the outer periphery of the output shaft 16 and the inner surface of the through hole 62 of the end plate 56, and this piston 77 is supported by the output shaft 16 and the end plate 56 so as to be movable in the axial direction. . If the piston 77 is arranged at such a position, the piston 77 is accommodated in the eccentric differential reduction gear 47, and the entire hydraulic drive device can be reduced in size. 78 is 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 provided between the piston 77 and the end plate 56. Is connected to a cylinder chamber 79 formed in 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 towards. 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. By the movement of the piston 77, the first and second drive gears 63, 64 compresses the spring 80 and moves integrally in one axial direction to mesh the first drive gear 63 and the first driven gear 75. On the other hand, when the pressure oil is not guided to the cylinder chamber 79, the piston 77 The first and second drive gears 63 and 64 are moved in the other axial direction by the movement of the piston 77, and the second drive gear 64 and the second driven gear 76 are moved by the biasing force of the spring 80. And bite. The piston 77, the passage 78, and the spring 80 described above as a whole move the first drive gear 63, the first driven gear 75, or the second drive gear 63, 64 by integrally moving the first and second drive gears 63, 64 in the axial direction. A moving mechanism 82 for selectively meshing the driving gear 64 and the second driven gear 76 is configured, and the first and second driving gears 63 and 64, the first and second driven gears 75 and 76, and the moving mechanism. As a whole, 82 is interposed between the output shaft 16 of the hydraulic motor 11 and the crankshaft 69 of the eccentric differential reduction gear 47, and constitutes a transmission means 83 for transmitting the rotation of the output shaft 16 to the crankshaft 69. . Note that 84 is interposed between the hub 48 and the casing 15 and the fixed carrier 55, a bearing that rotatably supports the hub 48 on the casing 15 and the fixed carrier 55, and 85 is between the hub 48 and the casing 15. A seal member 86 that is interposed and seals between them is a cover that is fixed to one end of the hub 48 and closes one end opening of the hub 48.
[0017]
Next, the operation of one embodiment of the present invention will be described.
When 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 protrudes 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 are inclined. Sliding on the surface 32 from the thick portion side toward the thin portion side, the plunger 23, 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 moves on the inclined surface 32 of the swash plate 31 from the thin portion side toward the thick portion side. The inclined surface 32 is gradually pushed into the cylinder hole 22, and the pressure oil in the cylinder hole 22 is discharged through the other arc-shaped 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 parts 71 of these crankshafts 69 are eccentrically rotated in the shaft hole 53 of the pinion 50 to cause the pinion 50 to perform an eccentric revolving motion. The hub 48 is slightly decelerated by the eccentric revolving motion of the pinion 50 and rotates at a low speed because it is slightly less.
[0018]
Here, when it is desired to rotate the hub 48 at the minimum number of rotations, the amount of pressure oil supplied to the cylinder hole 22 of the hydraulic motor 11 is minimized, and the supply of pressure oil to the cylinder hole 41 through the passage 43 is performed. To stop. As a result, the swash plate 31 is tilted to the first tilting position by the pressing force from the plunger 23, and the stroke of the plunger 23 is lengthened. As a result, the cylinder block 21 and the output shaft are coupled with the supply of the minimum amount of pressure oil. The number of revolutions of 16 is the lowest. At this time, pressure 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, and the first drive gear 63 and the first driven gear are moved. The 75 is meshed, and the rotation of the output shaft 16 is further decelerated by these first drive and driven gears 63 and 75, in this case, 1/3. As a result, the hub 48 rotates at the minimum rotational speed.
[0019]
On the other hand, when it is desired to rotate the hub 48 at the maximum number of rotations, the amount of pressure oil supplied to the cylinder hole 22 of the hydraulic motor 11 is maximized and the pressure oil is supplied to the cylinder hole 41 through the passage 43. As a result, the swash plate 31 is tilted to the second tilted position by the protrusion of the pressing piston 42, and the stroke of the plunger 23 is shortened. As a result, the cylinder block 21 and the output shaft 16 are coupled with the maximum amount of pressure oil supply. The number of revolutions is the highest. At this time, since the supply of pressure oil from the passage 78 to the cylinder chamber 79 is stopped, the piston 77, the first and second drive gears 63, 64 move to the other axial direction by the urging force of the spring 80. The second drive gear 64 and the second driven gear 76 mesh with each other. Since the second drive and driven gears 64 and 76 transmit the rotation at a constant speed, that is, without decelerating, the hub 48 has a maximum rotational speed. Will rotate.
[0020]
If the amount of pressure oil supplied to the hydraulic motor 11 is controlled as described above and the tilt position of the swash plate 31 of the hydraulic motor 11 is changed in two stages, the rotational speed of the output shaft 16 (the hub 48) The number of rotations) can be set within a predetermined range. 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 to thereby perform the first drive. If the gear 63 and the first driven gear 75 or the second drive gear 64 and the second driven gear 76 are selectively meshed with each other, the rotational speed of the output shaft 16 is 2 during transmission to the hub 48. The speed is further changed in stages, thereby further expanding the rotation speed range of the hub 48. 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, and at this time, two gears, specifically, the second drive and the driven gear 64 are used. , 76 and the moving mechanism 82 need only be added, so that the manufacturing cost can be reduced and the size can be reduced.
[0021]
Here, for example, a normal swash plate type hydraulic motor having a two-step change angle with a minimum rotation speed of 35 rpm and a maximum rotation speed of 3000 rpm and a normal eccentric differential reduction gear with a reduction ratio of 1/50 are used. In the case of the hydraulic drive system used, if the transmission means is composed of a gear train with a reduction ratio of 1/3 as in the prior art, the rotation speed of the hub is at least 0.23 rpm and at most 20 rpm. Usually requires a speed range of 0.3 rpm to 60 rpm and cannot be used as it is. However, if the second drive gear 64 and the second driven gear 76 are meshed 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 rotation speed range can be expanded), and it can be applied to asphalt finishers and the like.
[0022]
In the above-described embodiment, the rotation angle of the output shaft 16 is changed in two stages by changing the tilt angle of the swash plate 31 in two stages, but in the present invention, it is changed in three stages. You may do it. In the above-described embodiment, the first and second drive gears 63 and 64 are moved to the axial direction one side by the piston 77 and moved to the other axial direction side by the spring 80. The first and second drive gears may be coupled to each other, and pressure oil may be alternately guided to both end faces of the piston so that the first and second drive gears are moved in the axial direction only by the piston.
[0023]
【The invention's effect】
As described above, according to the present invention, the hub can be rotated at a wide range of rotation speeds while being small and inexpensive.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing one 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 ... 1st driven gear 76 ... 2nd driven gear
77 ... piston 78 ... passage
82 ... Movement mechanism 83 ... Transmission means

Claims (2)

A swash plate type hydraulic motor having an output shaft whose rotational speed changes in a plurality of stages by changing the tilt position of the swash plate into a plurality of stages, and a pinion that eccentrically rotates the rotation input to the crankshaft parallel to the output shaft An eccentric differential reducer that decelerates and outputs to the hub, and a transmission means that is interposed between the output shaft of the hydraulic motor and the crankshaft of the eccentric differential reducer and transmits the rotation of the output shaft to the crankshaft. The first and second drive gears having different pitch circle diameters are supported by the transmission means so as to be axially movable on the output shaft of the hydraulic motor and to rotate integrally with the output shaft. The first and second driven gears attached to the crankshaft and having different pitch circle diameters and the first and second drive gears are integrally moved in the axial direction to move the first drive gear and the first driven gear. Gears or second Dohaguruma, hydraulic drive apparatus characterized by having a moving mechanism for selectively engaging the second driven gears. A through hole is formed in the central portion of the eccentric differential reduction gear, the output shaft of the hydraulic motor is loosely fitted in the through hole, and the moving mechanism is disposed between the output shaft and the inner surface of the through hole. The hydraulic pressure according to claim 1, further comprising: a piston movable in the axial direction of the output shaft; and a passage for moving the first and second drive gears by guiding pressure oil to the piston and moving the piston in the axial direction. Drive device.

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