JPH10318339A - Speed reducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decelerate the rotation of an input shaft over a wide range, whereas it is compact in size and inexpensive in cost. SOLUTION: In this device, when speed is reduced at a low ratio, a first external gear 70 and a fourth external gear 79 are engaged with each other, carrying out a single reduction, but when the speed reduced at a high ratio, both first and third external gears 70 and 76 as well as both second and fourth external gears 72 and 79 are engaged with each other, whereby a rotation of an input shaft 69 is transmitted to an output shaft 75 via the first external gear 70, the third external gear 76, an internal gear 82, the second external gear 72 and the fourth external gear 79. With this constitution, a double reduction is carried out in succession, while the speed is largely reduced at the first stage used with the internal gear 82, and thus deceleration over a wide range is made achievable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed reducer capable of changing a speed reduction ratio in a wide range.

[0002]

2. Description of the Related Art In recent years, a wide range of rotational speed control has been performed for civil engineering construction machines, such as hydraulic shovels and wheel loaders, by controlling the flow rate of supplied pressure oil and changing the tilting position of a swash plate while being inexpensive. Swash plate type hydraulic motors that can be used in many cases, but when the rotation of such a hydraulic motor is transmitted to drive wheels such as a hydraulic shovel as it is,
Since the traveling speed of the hydraulic excavator or the like becomes too high, a speed reducer capable of decelerating at a high ratio is interposed between the hydraulic motor and the drive wheel to reduce the rotational speed of the drive wheel to an appropriate value. ing. Here, as such a speed reducer, for example, an eccentric differential type speed reducer and a gear type speed reducer, the gear type speed reducer meshes with each other to rotate,
For example, a gear composed of a pair of external gears that reduce the speed by half is often used.

Recently, it has been considered to use such a speed reducer with a hydraulic motor as a drive for driving an asphalt finisher or the like that requires a wider range of speed control, but the speed range is narrow as it is. Could not be used. For this reason, the present applicant has filed Japanese Patent Application
In the specification of JP-A-78871, a first drive gear and a second drive gear which are axially movable on an output shaft of a hydraulic motor and are supported so as to rotate integrally with the output shaft and have different pitch circle diameters, and First and second driven gears attached to each other and having different pitch circle diameters and the first and second driven gears are integrally moved in the axial direction to integrally move the first and second driven gears or the second driven gear. A gear type speed reducer provided with a gear and a moving mechanism for selectively meshing the second driven gear with each other has been proposed.

[0004]

Here, such a speed reducer can be used for an ordinary asphalt finisher or the like because the speed range can be extended to a considerable extent, but it has been recently proposed. It was not enough for high-performance asphalt finishers.

SUMMARY OF THE INVENTION An object of the present invention is to provide a speed reducer that can reduce the rotation of an input shaft over a wide range while being small and inexpensive.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an input shaft which is rotated by receiving a driving force, and which is supported by the input shaft so as to be movable in the axial direction, and which rotates integrally with the input shaft to form an outer periphery. A first external gear having external teeth formed thereon, and the first external gear is supported movably in the axial direction by an input shaft on one side of the first external gear, and freely rotates with respect to the input shaft to form external teeth on the outer periphery; A second external gear, an output shaft extending parallel to the input shaft, a third external gear supported on the output shaft so as to be freely rotatable, and having external teeth formed on an outer periphery thereof, and a first external gear on one side of the third external gear. A fourth external gear connected to the output shaft so as to rotate integrally therewith and having external teeth formed on the outer circumference; and an external tooth of the third external gear disposed on the inner circumference and disposed radially outside the third and fourth external gears. A cylindrical portion having internal teeth that always mesh with the second external gear; The first external gear is formed by moving the first and second external gears integrally in the axial direction, the internal gear being constituted by a disk portion which is rotatably supported and integrally rotates with the second external gear. , The external teeth of the third external gear, the external teeth of the second external gear and the external teeth of the fourth external gear, or
This can be achieved by providing a moving mechanism that selectively meshes the external teeth of the external gear and the external teeth of the fourth external gear.

Now, when the first and second external gears are integrally moved to one side in the axial direction by the moving mechanism, and the external teeth of the first external gear and the external teeth of the fourth external gear mesh with each other. I do.
At this time, the rotation of the input shaft is reduced to the ratio of the number of external teeth of the first and fourth external gears, transmitted to the output shaft, and rotates the output shaft. At this time, the external teeth of the third external gear do not mesh with the external teeth of the first external gear, and the second external gear rotates freely with respect to the input shaft. And the internal gear does not receive the driving force. Next, when transmitting the rotation of the input shaft to the output shaft at a higher speed,
The first and second external gears are integrally moved to the other side in the axial direction by the moving mechanism, and the external teeth of the first external gear and the external teeth of the third external gear and between the external teeth of the second external gear and the fourth external gear. The external teeth of the gear mesh with each other. As a result, the rotation of the input shaft is controlled by the first external gear, the third
The rotation is transmitted to the output shaft while being reduced via the external gear, the internal gear, the second external gear, and the fourth external gear. When this rotation is transmitted from the first external gear to the internal gear, First, the speed is reduced according to the ratio of the number of teeth of the external gear of the external gear to the number of internal teeth of the internal gear, and when the gear is transmitted from the second external gear to the fourth external gear, the second and fourth external gears The speed is reduced to the ratio of the number of external teeth, and consequently the speed is reduced to the product of the ratio of both teeth. In this way, the former is one-stage reduction of the external gears, whereas the latter is reduced to two stages,
Moreover, in the first stage of deceleration, the transmission side is an internal gear having a large number of teeth, so that the reduction ratios of the two are greatly different.
The deceleration range can be considerably widened. For this reason, this reduction gear can be used for a high-performance asphalt finisher or the like that requires a wide range of speed control, and at this time, it is only necessary to add an internal gear. Can also be planned.

Further, according to the second aspect, the rotation of the output shaft can be further reduced at a high ratio.
It is suitable for asphalt finishers and the like that require low-speed rotation. Furthermore, according to the structure described in claim 3, the piston is housed in the eccentric differential type reduction gear, and the entire device can be reduced in size. Further, according to the structure described in claim 4, the transmission of the rotational driving force can be cut off inside the speed reducer, and the transmission system subsequent to the output shaft can be freely rotated. Further, according to the structure described in claim 5, it can be used as a drive device capable of controlling a wide range of rotation speed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 11 denotes a swash plate type hydraulic motor mounted on a traveling frame of a high performance asphalt finisher, for example.
11 has a case main body 13 in which a storage chamber 12 is formed, and a side plate 14 fixed to the other end of the case main body 13 and closing the other end opening of the storage chamber 12 to form a closed space, The case body 13 and the side plates 14 constitute a casing 15 as a whole. Reference numeral 16 denotes a rotating shaft whose other side is inserted into the storage chamber 12. The rotating shaft 16 is rotatably supported by the side plate 14 and the case body 13 via a bearing 17. One side of the rotating shaft 16 protrudes from the case body 13 toward one side.

Reference numeral 21 denotes a cylindrical cylinder block housed in the storage chamber 12, into which the other end of the rotary shaft 16 is inserted and connected by a spline. The cylinder block 21 is a rotating 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
16 are penetrating. The swash plate 31 has, at the other end facing the cylinder block 21, an inclined surface 32 that is inclined with respect to a plane perpendicular to the rotation axis of the rotating 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.
1st tilting position (FIGS. 1 and 2)
2) and a second tilt position where the first flat portion 33a and the inner surface of one end of the storage chamber 12 are in surface contact with each other. 35 is all shoes
A substantially ring-shaped retainer plate engaged with 25 is in spherical contact with the inner periphery of the retainer plate 35, and a thrust ball fitted to the outside of the rotary shaft 16 and connected by a spline connection, 37 is a transmission ball. This is a spring that applies a biasing force toward one side via the 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. Accordingly, 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 rotating shaft 16 is changed in two stages, thereby enabling a wide range of rotation speed control.

In FIG. 1, reference numeral 47 denotes an eccentric differential speed reducer. The hydraulic motor 11 is attached to the other end of the eccentric differential speed reducer 47. The eccentric differential reducer 47 has a substantially cylindrical hub 48, which is connected to the drive wheels of the asphalt finisher. At the center in the axial direction of the inner periphery of the hub 48, a large number of cylindrical internal tooth pins 49 are inserted by almost half, and these internal tooth pins 49 extend in the axial direction and are separated by an equal distance in the circumferential direction. It is arranged. Two disc-shaped pinions are provided in the hub 48
50 are housed, and the inner teeth pins 49 are provided on the outer periphery of each pinion 50.
The external teeth 51 having a slightly smaller number of teeth than the number of the internal teeth pins 49 are formed. Each of the pinions 50 has a plurality of through holes 52 and a plurality of through holes 53.
Are formed respectively. Reference numeral 55 denotes a fixed carrier housed in the hub 48, and the fixed carrier 55 is a pinion 50
A disk-shaped end plate 56 arranged on one side, and one end plate 56
And a hydraulic motor at the other end.
And a connector 58 integrally connected to the eleven case body 13. The connecting bodies 58 extend in the axial direction and are loosely fitted in the loose fitting holes 52 of the pinion 50. Numeral 59 denotes a plurality of crankshafts extending in parallel with the rotary shaft 16, and both ends of the crankshafts 59 are rotatably supported by the case body 13 and the end plate 56 via rolling bearings 60, respectively. Each crankshaft 59 has two eccentric portions 61 eccentric in the opposite direction from the central axis of the crankshaft 59 at the axial center thereof, and these eccentric portions 61 are needle roller bearings in shaft holes 53 of the pinion 50. Each is inserted with 62 interposed. When the crankshaft 59 rotates around the central axis, the eccentric portions 61 of the crankshaft 59
The eccentric rotation in 53 causes the pinion 50 to eccentrically revolve, but at this time, since the number of the external teeth 51 is slightly smaller than the number of the internal teeth pins 49, the hub 48 is greatly decelerated by the eccentric revolving motion of the pinion 50. Rotating at low speed. The aforementioned hub 48,
The pinion 50, the fixed carrier 55, and the crankshaft 59 constitute the eccentric differential reducer 47 as a whole, and such an eccentric differential reducer 47 reduces the rotation of the crankshaft 59 at a high ratio as described above. Since it can be decelerated, it is suitable for driving an asphalt finisher or the like that requires low-speed rotation.
63 and 64 are through holes formed in the center of the eccentric differential type reduction gear 47, more specifically, on the central axis of the pinion 50 and the end plate 56, respectively. 11
The center of the rotary shaft 16 is loosely fitted.

In FIGS. 1 and 3, reference numeral 68 denotes a gear type speed reducer. The eccentric differential type speed reducer is provided on the other side of the gear type speed reducer 68.
47 are located. The gear-type speed reducer 68 has an input shaft 69 that rotates by receiving a driving force at a central portion, and the input shaft 69 is formed integrally with the rotary shaft 16 of the hydraulic motor 11. It corresponds to one end of 16. 70 is the input shaft
The first external gear 70 is spline-coupled to the first external gear 70 so as to be axially movable on the input shaft 69 and supported so as to be able to rotate integrally with the input shaft 69. Teeth 71 are formed. One side of the first external gear 70 has a second axial length substantially twice the axial length of the first external gear 70.
An external gear 72 is provided.
73 are formed over almost the entire length. Also, this second
The input shaft 69 is inserted into a through hole 74 formed on the center axis of the external gear 72, and as a result, the second external gear 72 is connected to the input shaft 69 on one side of the first external gear 70. In this manner, the input shaft 69 is supported so as to freely rotate with respect to the input shaft 69.

Reference numeral 75 denotes an output shaft extending parallel to the input shaft 69. The output shaft 75 is formed integrally with the crankshaft 59 of the eccentric differential reducer 47, and an end plate of the crankshaft 59 is provided.
It corresponds to one end protruding from 56. Reference numeral 76 denotes a third external gear as an idle gear which is supported on the output shaft 75 via a needle roller bearing 77 so as to be freely rotatable.
External teeth 78 are formed on the outer periphery of 76. The external teeth 78 of the third external gear 76 can mesh with the external teeth 71 of the first external gear 70. A fourth external gear 79 is connected to the output shaft 75 on one side of the third external gear 76 so as to be able to rotate integrally with the output shaft 75 by spline coupling. External teeth 80 are provided on the outer periphery of the fourth external gear 79. Is formed. And this fourth external gear 79
Of the first external gear 70 or the second external gear 72
Can be selectively engaged with any one of the external teeth 73 of the first embodiment.
Reference numeral 82 denotes an internal gear that is coaxial with the input shaft 69 and has a cylindrical shape with a bottom.
The internal gear 82 has a cylindrical portion 83 disposed radially outside the third and fourth external gears 76 and 79. On the inner periphery of the other side of the cylindrical portion 83, there are formed internal teeth 84 which are always meshed with the external teeth 78 of the third external gear 76, and the number of these internal teeth 84 is the external teeth 71 of the first external gear 70. Considerably more than the number of teeth. The fourth external gear
On one side of 79, a disk-shaped disk portion 85 is arranged, and a radially outer end of the disk portion 85 is integrally connected to one end of the cylindrical portion 83. The radial inner end of the disk portion 85 has a second
Internal teeth 86 of the same number as the external teeth 73 of the external gear 72 are formed, and these internal teeth 86 always mesh with the external teeth 73 of the second external gear 72 with all the teeth. As a result, the disk portion 85 is supported by the second external gear 72 so as to be movable in the axial direction, and the second external gear 72
And can rotate together. The cylindrical part 83 described above,
The disk portion 85 constitutes the internal gear 82 as a whole.

When the first and second external gears 70 and 72 move integrally in the axial direction, the external teeth 71 of the first external gear 70 and the external teeth 78 of the third external gear 76 and the second external gear 72 external teeth 73 and 4
The external teeth 80 of the external gear 79 or the external teeth 71 of the first external gear 70
And the external teeth 80 of the fourth external gear 79 are selectively meshed with each other. When the gears are meshed as in the former, the rotation of the input shaft 69 is transmitted from the first external gear 70 to the internal gear 82. sometimes,
The gear ratio of the external teeth 71 of the first external gear 70 to the internal teeth 84 of the internal gear 82 is reduced to, for example, 1/5, and then transmitted from the second external gear 72 to the fourth external gear 79. Sometimes, the second and fourth external gears
The gear ratio of the external teeth 73, 80 of 72, 79 is reduced to, for example, 1/2,
As a result, the product is transmitted to the output shaft 75 after being greatly decelerated to the product of the ratio between the two teeth, here 1/10. On the other hand, when the gears are engaged as in the latter case, the rotation of the input shaft 69 is restricted to the first and fourth external gears 7.
The gear ratio of the external teeth 71 and 80 of 0 and 79 is reduced to, for example, 1/2, and transmitted to the output shaft 75.

Reference numeral 90 denotes a central portion of the eccentric differential speed reducer 47, specifically, between the outer periphery of the rotary shaft 16 and the inner surface of the through hole 64 of the end plate 56. The piston 90 is in contact with the rotating shaft 16, the end plate 56.
Are supported movably in the axial direction. If the piston 90 is arranged at such a position, the piston 90 is housed in the eccentric differential speed reducer 47, and the entire device can be reduced in size. On the other side of the piston 90, a cylindrical stopper 91 supported by the case body 13 is provided, and the stopper 91 is fitted outside the rotary shaft 16. Reference numeral 92 denotes a spring interposed between a step provided at the other end of the stopper 91 and the other end surface of the piston 90. The spring 92 applies a biasing force toward the piston 90 to one side, and the piston 90 90, first and second external gears 70,
72 is moved to one side integrally. Reference numeral 93 denotes a passage formed in the casing 15 and the fixed carrier 55, and this passage
One end of 93 is connected to a hydraulic pressure source via a switching valve (not shown), and the other end is connected to a cylinder chamber 94 formed between the piston 90 and the end plate 56. When the pressure oil is guided to the cylinder chamber 94 through the passage 93, the piston 90 is pressed by the pressure oil and moves to the other side in the axial direction while compressing the spring 92. Reference numeral 95 denotes a spring interposed between a spring receiver 96 attached to one end of the input shaft 69 and the second external gear 72, and this spring 95
0 and 72 are biased toward the other side. Here, the biasing force of the spring 95 is smaller than the biasing force of the spring 92. As a result, when the piston 95 moves to the other side until the piston 90 comes into contact with the stopper 91, the first and second external forces are reduced. The gears 70 and 72 follow the piston 90 and move to the other side.

When the pressure oil is guided to the cylinder chamber 94 through the passage 93, the piston 90 is pressed by the pressure oil and moves to the other side in the axial direction until it comes into contact with the stopper 91 while compressing the spring 92. At this time, the first and second external gears 70 and 72 move integrally to the other side in the axial direction by the urging force of the spring 95, and the external teeth 71 of the first external gear 70 and the third external gear
The external teeth 78 of 76 and the external teeth 73 of the second external gear 72 and the external teeth 80 of the fourth external gear 79 mesh with each other. On the other hand, the cylinder chamber 94
When the pressure oil is no longer guided to the
The first and second external gears 70 and 72 move integrally to one side in the axial direction while compressing the spring 95 by the movement of the piston 90 due to the urging force of the piston 90. The external teeth 71 of the first external gear 70 mesh with the external teeth 80 of the fourth external gear 79. Piston 9 described above
0, stopper 91, spring 92, passage 93, spring 9
5 as a whole, by moving the first and second external gears 70 and 72 integrally in the axial direction, the external teeth 71 of the first external gear 70 and the third
The external teeth 78 of the external gear 76, the external teeth 73 of the second external gear 72 and the external teeth 80 of the fourth external gear 79, or the external teeth of the first external gear 70
The moving mechanism 97 selectively meshes the external teeth 80 of the fourth and fourth external gears 79 with each other. The input shaft 69, the first, second, third, and fourth external gears 70, 72, 76 , 79, the output shaft 75, and the moving mechanism 97 as a whole are interposed between the rotary shaft 16 of the hydraulic motor 11 and the crankshaft 59 of the eccentric differential reducer 47, and rotate the rotary shaft 16 to the crankshaft. The gear type speed reducer 68 for transmitting the gears to the gear 59 at a reduced speed is constituted. Reference numeral 98 denotes a bearing interposed between the hub 48 and the casing 15 and the fixed carrier 55, and a bearing for rotatably supporting the hub 48 on the casing 15 and the fixed carrier 55.99 denotes a bearing between the hub 48 and the casing 15. It is a sealing member that is interposed and seals between them.

The hub 101 is fixed to one end of the hub 48,
A central portion of a screw shaft 102 coaxial with the input shaft 69 is rotatably supported on the cover plate 101, and a male screw portion is provided on the other side of the screw shaft 102. 103
Is provided. Reference numeral 104 denotes a movable member which is coaxial with the input shaft 69 and has a substantially cylindrical shape with a bottom. The male screw portion 103 is screwed into a bottom wall located at one end of the movable member 104.
The other end of the movable member 104 is formed with a claw 105 extending inward in the radial direction.
Can be brought into contact with a ring plate 106 attached to one end of the ring. Reference numeral 107 denotes a knob fixed to one end of the screw shaft 102. When the screw shaft 102 is rotated by the knob 107, the amount of screwing of the male screw portion 103 into the movable member 104 changes, and the movable member 104 is moved in the axial direction. Go to The external teeth 71 of the first external gear 70 and the external teeth 78 of the third external gear 76
And the external teeth 73 of the second external gear 72 and the external teeth of the fourth external gear 79
When the screw member 102 is rotated to move the movable member 104 to one side in the axial direction while the members 80 are engaged with each other, the claw 105 contacts the ring plate 106. Is further moved to one side in the axial direction.
Only the second external gear 72 is moved to one side in the axial direction while compressing the spring 95 by being hooked on the
The external teeth 73 of the external gear 72 are disengaged from the engagement with the external teeth 80 of the fourth external gear 79. The screw shaft 102, the movable member 104, the ring plate 106, and the knob 107 described above are provided on one side of the input shaft 69 as a whole, and move only the second external gear 72 to one side to form the second external gear 72. A detaching mechanism 108 for detaching the external teeth 73 from engagement with the external teeth 80 of the fourth external gear 79 is provided. In addition, 109
Is detachably attached to the lid plate 101, and the knob 107
The cover 110 is a bearing interposed between the internal gear 82 and the cover plate 101.

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 rotating 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 rotary shaft 16 is transmitted to the crankshaft 59 of the eccentric differential reducer 47 via the gear type reducer 68, and rotates each crankshaft 59 around the center axis. As a result, the eccentric portion 61 of the crankshaft 59 eccentrically rotates within the shaft hole 53 of the pinion 50 to cause the pinion 50 to eccentrically revolve.
Since the number of the pins 51 is slightly smaller than the number of the internal teeth pins 49, the hub 48 is largely 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 highest rotational speed, 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. Supply. As a result, the swash plate 31 is tilted to the second tilting position by the projection of the pressing piston 42, and the stroke of the plunger 23 is shortened. As a result, the cylinder block 21 and the rotating shaft 16 Rotation speed is the highest. At this time, since the supply of the pressure oil from the passage 93 to the cylinder chamber 94 is stopped, the piston 90 moves to one side in the axial direction until the stroke end due to the urging force of the spring 92. The first and second external gears 70 and 72 move integrally to one side in the axial direction while compressing the spring 95, and the external teeth 71 of the first external gear 70
And the external teeth 80 of the fourth external gear 79 mesh with each other. At this time, the rotation of the rotary shaft 16 (input shaft 69) is reduced to the ratio of the number of the external teeth 71, 80 of the first and fourth external gears 70, 79, in this case only to 1/2, and the crankshaft 59 is reduced. (The output shaft 75), the hub 48 rotates at the maximum rotation speed. At this time, the external teeth 78 of the third external gear 76 do not mesh with the external teeth 71 of the first external gear 70, and the second external gear 72 rotates freely with respect to the input shaft 69. 2, third external gear 7
2, 76 and the internal gear 82 do not receive the driving force.

On the other hand, when it is desired to rotate the hub 48 at the lowest rotational speed, the rotation of the rotating shaft 16 (input shaft 69) is reduced at the highest ratio.
The supply of pressurized oil to the hydraulic motor 11 is temporarily stopped, and the rotation of the hydraulic motor 11 is stopped. Next, the pressure oil is supplied to the cylinder chamber through the passage 93.
The piston 90 is moved to the other side in the axial direction until the piston 90 comes into contact with the stopper 91 by the pressure oil. As a result, the first and second external gears 70 and 72 move integrally to the other side in the axial direction by the urging force of the spring 95, and the external teeth 71 of the first external gear 70
And the external teeth 78 of the third external gear 76 and the external teeth of the second external gear 72
73 and the external teeth 80 of the fourth external gear 79 mesh with each other. In this state, the minimum amount of pressure oil is supplied to the cylinder hole 22 of the hydraulic motor 11 and the supply of pressure oil to the cylinder hole 41 through the passage 43 is stopped. As a result, the swash plate 31 is tilted to the first tilt position by the pressing force from the plunger 23, and
The length of the stroke of the cylinder block 21 and the rotation shaft 16 is minimized in combination with the supply of the minimum amount of pressure oil. Next, the rotation of the rotary shaft 16 (input shaft 69) is caused by the first gear because the gears are engaged as described above.
While being reduced via the external gear 70, the third external gear 76, the internal gear 82, the second external gear 72, and the fourth external gear 79, the power is transmitted to the crankshaft 59 (output shaft 75). When transmitted from the first external gear 70 to the internal gear 82, the external teeth 71 of the first external gear 70
The ratio of the number of teeth of the internal gear 82 to the number of internal teeth 84, here, 1/5, is first reduced and then transmitted from the second external gear 72 to the fourth external gear 79. 4 External teeth 73, 80 of external gears 72, 79
Is reduced to 1/2 here, and consequently the product of the ratio of both teeth, here 1/10, is transmitted. As a result, the hub 48 rotates at the minimum rotational speed. In this way, at the highest rotation speed, the gear is reduced by one stage from the gear 70 to 79. At the lowest rotation speed, the gear is reduced to two stages from the gear 70 to 82 and from 72 to 79. Since the transmission side is an internal gear 82 with a large number of teeth, the reduction ratio (1/2 and 1/10) at the highest speed and lowest speed rotation is greatly different, and as a result, it is possible to reduce the speed in a fairly wide range. it can. For this reason, it is possible to use the present speed reducer for a high-performance asphalt finisher or the like that requires a wide range of speed control, and at this time, it is only necessary to add the internal gear 82, so that the manufacturing cost is reduced. The size can be reduced.

If the asphalt finisher or the like equipped with such a speed reducer breaks down and needs to be pulled, the piston 90 is moved to the other side in the axial direction and the external teeth 71 of the first external gear 70 are moved. And the external teeth 78 of the third external gear 76 and the second
After the external teeth 73 of the external gear 72 mesh with the external teeth 80 of the fourth external gear 79, the knob 107 is rotated to rotate the screw shaft 102. As a result, the movable member 104 moves to one side in the axial direction and the claw 105 comes into contact with the ring plate 106. After such contact, the movable member 104 is further moved to one side in the axial direction,
Only the external gear 72 is hooked on the movable member 104 and moved to one side in the axial direction. As a result, the second external gear 72 is disengaged from the fourth external gear 79, and the transmission of the rotational driving force from the input shaft 69 to the output shaft 75 is interrupted inside the gear type reduction gear 68, and the transmission after the output shaft 75 The system can rotate freely and traction is easy.

In the above embodiment, the swash plate 31 is used.
By changing the tilt angle of the rotary shaft 16 in two steps, the number of rotations of the rotary shaft 16 is changed in two steps. However, in the present invention, it may be changed in three steps. In the above-described embodiment, the first and second external gears 70 and 72 are
0, the spring 95 is moved to the other side in the axial direction, and the spring 92 is moved to the one side in the axial direction. However, in the present invention, the first and second external gears are connected to the piston and both end faces of the piston are The first and second external gears may be moved in the axial direction only by the piston by alternately guiding the pressure oil.

[0025]

As described above, according to the present invention, the rotation of the input shaft can be reduced over a wide range while being small and inexpensive.

[Brief description of the drawings]

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

FIG. 2 is a front sectional view showing a part of the hydraulic motor.

FIG. 3 is a front sectional view showing a part of a gear type speed reducer.

[Explanation of symbols]

 11 ... Swash plate type hydraulic motor 16 ... Rotating shaft 31 ... Swash plate 47 ... Eccentric differential reducer 48 ... Hub 50 ... Pinion 59 ... Crank shaft 69 ... Input shaft 70 ... First external gear 71 ... External teeth 72 ... Second External gear 73 ... External tooth 75 ... Output shaft 76 ... Third external gear 78 ... External tooth 79 ... Fourth external gear 80 ... External tooth 82 ... Internal gear 83 ... Cylindrical part 84 ... Internal tooth 85 ... Disk part 90 ... Piston 93 ... passage 97 ... moving mechanism 108 ... detachment mechanism

Claims (5)

[Claims] An input shaft that is rotated by a driving force, and a first external gear that is supported by the input shaft so as to be movable in the axial direction, rotates integrally with the input shaft, and has external teeth formed on the outer periphery. A second external gear supported by the input shaft on one side of the first external gear so as to be movable in the axial direction, freely rotating with respect to the input shaft, and having external teeth formed on the outer periphery thereof; An output shaft extending in parallel with the first shaft, a third external gear supported on the output shaft so as to be freely rotatable, and having external teeth formed on the outer periphery, and connected to the output shaft on one side of the third external gear so as to rotate integrally therewith, A fourth external gear having external teeth formed on an outer periphery thereof; and a cylindrical portion having radially outside the third and fourth external gears and having internal teeth always meshing with the external teeth of the third external gear on the inner periphery. And one side of the fourth external gear, which is supported by the second external gear so as to be movable in the axial direction, and By moving the first and second external gears integrally in the axial direction with the internal gear composed of a disk portion that rotates integrally with the vehicle, the external gear of the first external gear and the external gear of the third external gear are moved. A moving mechanism for selectively meshing the teeth with each other and the external teeth of the second and fourth external gears or the external teeth of the first and fourth external gears; A speed reducer characterized by the above-mentioned. 2. An eccentric differential type reduction gear for reducing the rotation input to a crankshaft by a pinion rotating eccentrically and outputting the reduced rotation to a hub on the other side of the first and third external gears. The reduction gear according to claim 1, wherein the shaft and the crankshaft are formed integrally. 3. The first moving mechanism according to claim 1, wherein the moving mechanism comprises a piston disposed at a central portion of the eccentric differential type speed reducer, the piston being movable in an axial direction, and a hydraulic oil being guided to the piston to move the piston in the axial direction. And a passage for moving the second external gear. 4. When the external teeth of the first external gear and the external teeth of the third external gear mesh with each other and the external teeth of the second external gear and the external teeth of the fourth external gear mesh with each other, only the second external gear is used. 2. The reduction gear transmission according to claim 1, further comprising a release mechanism for moving the first external gear to one side to release the external teeth of the second external gear from meshing with the external teeth of the fourth external gear. 5. A swash plate type hydraulic motor having a rotating shaft whose rotation speed changes to a plurality of stages by changing the tilt position of the swash plate to a plurality of positions, is provided on the other side of the eccentric differential type speed reducer. 3. The reduction gear transmission according to claim 2, wherein the input shaft and the rotation shaft are integrally formed.