JPH0520616B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reduction gear for a traveling device of a crawler vehicle used in construction machinery.

[Prior art]

Among construction machinery, crawler vehicles that are not required to run at high speeds are required to have a low rotational speed and high torque for driving the traveling device. When a hydraulic motor is used as the power source, a hydraulic motor that outputs high torque at a low rotational speed requires a large pressure-receiving area and becomes large in size.

Most construction machinery is used on unleveled areas. Further, the above-mentioned drive device is attached to the crawler portion and is located close to the ground surface. Therefore, if the power source is installed with the power source protruding sideways from the crawler part, there are problems such as damage from hitting rocks while the construction machine is running, so there has been a demand for downsizing of the power source. .

Therefore, in order to downsize the power source, it is necessary to integrate a low-torque, high-speed hydraulic motor and a reduction gear.
Achieved miniaturization with a structure that produces high torque and low rotational speed output.

An example of this type of technology is the technology shown in Figure 2 (Japanese Patent Publication No. 7131/1983). The invention comprises a hydraulic motor 11, a reducer 12 having an input shaft connected to an output shaft of the hydraulic motor 11, a flange in which the reducer 12 and the hydraulic motor 11 are housed, and a flange to which a sprocket of a crawler device is attached. 13 and a hub 14. In the hydraulic motor with a reduction gear having the above configuration, when pressure oil is supplied and discharged from the port 15 of the hydraulic motor 11, the piston 17 of the piston housing 16 is pressed against the swash plate 18,
The output shaft 19 rotates by that force. (Now assume that the rotation direction of the output shaft is clockwise when viewed from the right side of the diagram.)
This rotation is transmitted to the speed reducer 12 via the input shaft 20 connected to the output shaft 19.

The reducer 12 includes a sun gear 21 fixed to an input shaft 20, this sun gear 21, and this sun gear 21.
A first planetary gear 22 that meshes with the first planetary gear 22, a planetary gear base 24 that supports a second planetary gear 23 integrally connected to the first planetary gear 22 by a shaft 24a, and an internal gear 25 fixed to the casing 11A of the hydraulic motor 11. This internal gear 25 has a first
The second planetary gear 23 meshes with the planetary gear 22.
It meshes with an internal gear 14a provided on the hub 14.

As mentioned above, when the input shaft 20 is rotated clockwise, the first and second planetary gears 22 and 23
is rotated counterclockwise, and the planetary gear train 24 is rotated clockwise. Therefore, the hub 14 rotates counterclockwise.

This reducer applies a planetary gear device, and this device meshes a large number of gears (for example, meshes the first and second planetary gears 22 and 23 in FIG. 2) to increase the reduction ratio. ), which increases the axial dimension. If the dimension increases in the axial direction in this way, a part of the hydraulic motor or reduction gear will protrude from inside the crawler, which has the disadvantage of increasing the risk of damage during running.

That is, the drawback of the above-mentioned speed reducer is due to the fact that it is necessary to mesh a large number of gears in order to obtain a high speed reduction ratio.

In order to solve this drawback of increasing the axial dimension, a reduction gear shown in FIGS. 3a and 3b (Japanese Patent Laid-Open No. 56-39341) has been proposed. In this reducer, a projecting portion 32 is provided on a main body 31 to which a hydraulic motor 30 is attached, and an end plate 33 is fixed to this projecting portion. As shown in FIG. 3b, the protrusion 32 has
There are three recesses recessed from the outside toward the center, and an eccentric shaft 34 is installed in each recess.
As shown in Figure a, the main body 31 and the end plate 33 are supported via bearings. Two external gears 35, 35 are provided on this eccentric shaft 34 via bearings. Moreover, at one end of the eccentric shaft 34,
A gear 40 is fixed, and this gear 40 meshes with a gear 41 provided on a shaft 42 that is connected to the output shaft 30a of the hydraulic motor 30 and passes through the center of the protrusion 32. The external gears 35, 35 are connected to a hub 37.
It meshes with an internal gear 36 (pin gear) provided at. This hub 37 is supported by the main body 31 and the end plate 33 via bearings.

In the above-mentioned speed reducer, when the shaft 42 is rotated counterclockwise by the hydraulic motor 30, the rotation is reduced in the first stage through the gears 41 and 40, and is transmitted to the eccentric shaft 34. Rotate clockwise. Therefore, the external gear 35 is rotated clockwise by the rotation of the eccentric shaft 34 without rotating on its own axis. This revolution causes the external gear 35 and the internal gear 36 to perform a second stage of deceleration, causing the internal gear 36 and the hub 37 to rotate clockwise.

[Problem that the invention seeks to solve]

The conventional speed reducer explained in FIGS. 3a and 3b is as follows:
The number of meshing gears is reduced to reduce the lateral dimension. For this purpose, an operating gear mechanism is used, the internal gear being a pin gear, and the external gear having a tooth profile of a pericycloid parallel curve. While this reducer is in operation,
The internal gear and the external gear have a structure in which a large number of teeth mesh together at the same time (the teeth on the load transmission side of the external gear mesh at the same time). However, high torque acts on the reducer, which tends to cause tooth deformation, errors in center distance, and errors in tooth profile (in particular, since the pericycloid curve is formed by a circular envelope, machining accuracy may be affected). ), and the tooth profile formed by the pericycloid parallel curve is formed by a circular envelope as described above, and the root is concave but the tooth tip is a convex curve. That is, since the center position of the radius of curvature changes from the outside to the inside, the inflection point where the shape changes from concave to convex engages with the convex portion of the pin. For this reason, the surface pressure on the tooth surfaces during meshing rotation increases. Therefore, when the transmitted load is relatively small, it is possible to achieve the above-mentioned problem of reducing the axial dimension, but as the load increases, the tooth surface pressure increases as described above. It is necessary to take some measures such as increasing the tooth width. Because of this, there was a problem that miniaturization was difficult.

In addition, under light loads, there are no teeth that are in a state of meshing but not in a state of meshing, so if one of the teeth in a state of meshing is damaged during load transmission, the other teeth will be damaged one after another. Therefore, there is a problem that the crawler runs on its own. (If this happens, especially when loading construction machinery onto a vehicle,
Construction equipment moves on its own and falls from the vehicle. ) [Means for solving the problems] Means for solving the above problems of the present invention are as follows:
A hydraulic motor is installed inside the hydraulic motor and is attached to the crawler vehicle body. The hydraulic motor body rotatably supports a hub of a crawler drive sprocket having an internal gear, and an eccentric shaft having an eccentric part connected to the output shaft of the hydraulic motor. The hydraulic motor main body is rotatably supported, and the eccentric portion of the eccentric shaft rotatably supports an external gear meshing with the internal gear via a bearing, and the external gear is rotatably supported on the eccentric portion of the eccentric shaft via a bearing. A plurality of carrier pins are provided that pass through the external gear and have one end fixed to the hydraulic motor main body, with a margin between them and the outer periphery of the gear so as to allow the revolution of the gear and suppress its rotation. The tooth profiles of the toothed gear and the external gear are formed by involute curves, the difference in the number of teeth between the internal gear and the external gear is set to 1, and the theoretical meshing ratio thereof is made smaller than 1.

[Effect]

Since the present invention has the above technical means, it operates as follows.

(a) When the eccentric shaft is rotated in a predetermined direction by the output shaft generated by the rotation of the hydraulic motor, for example clockwise when viewed from one end of the eccentric shaft, the external gear is rotated on the eccentric portion of the eccentric shaft. Therefore, it is driven and moves as follows. That is, the external gear does not rotate because it is restrained by the carrier pin, but revolves around a circle whose radius is the eccentricity of the eccentric portion. By one revolution of the external gear, the meshing internal gear is rotated in the same clockwise direction as described above by the difference in the number of teeth from the external gear, that is, one tooth (one pitch). When the number of teeth of the internal gear is N, when the eccentric shaft rotates N times, that is, when the external gear revolves N times, the internal gear rotates once in the same direction. Therefore, the rotational speed of the hydraulic motor is reduced to 1/N and transmitted to the hub provided with the internal gear, and the crawler is driven via the sprocket at the reduced rotational speed.

Note that the external gear may be composed of one piece, but
When composed of two sheets, the overall engagement rate is 1.
Eccentric shafts are installed so that they are close to each other in the axial direction, and the positions where each external gear meshes with the internal gear are equally spaced in the circumferential direction with a phase difference of 180°. This is good in terms of the dynamic balance in the rotation of the shaft and the balance of the acting force in the direction perpendicular to the eccentric axis due to the load.

(b) Since the internal gear and the external gear are involute gears in which the tooth profile curves are involute curves, it is possible to reduce tooth surface pressure during load transmission. In other words, with an involute tooth profile, when a load is transmitted, even if the center distance changes due to the pressure angle, only the backlash changes. In addition, when the teeth of an internal gear and an external gear mesh, the tooth surfaces are concave and convex, and the involute curve is formed by a straight envelope, resulting in high machining accuracy. . Therefore, the accuracy of the entire speed reducer is maintained high and the structure is not easily affected by high load transmission, so that the surface pressure on the tooth surfaces can be reduced.

(c) The theoretical meshing ratio is determined by the number of teeth of the two gears that mesh. In other words, as the number of teeth increases, the meshing ratio increases, but the radial dimension of the gear also increases accordingly. Therefore, the theoretical meshing ratio is reduced and the radial dimension of the reducer is reduced. Furthermore, the theoretical engagement rate
By making the tooth smaller than 18, even if a meshing tooth breaks during load transmission, that breakage will not continue to the next tooth. In other words, when the meshing ratio is set to 1 or higher as described above, if the meshing teeth break, the meshing ratio becomes 1 or lower and the load concentrates on the meshing teeth, causing the teeth to break one after another. become. but,
If the engagement ratio is set lower than 1 from the beginning, even if the meshing teeth are damaged and the next tooth has to support the load, the design is such that one tooth can withstand the load. Since it has been protected, it will not be damaged in the future.

Also, if the theoretical engagement ratio is made smaller than 1, the angular velocity of rotation will change.
In other words, it is theoretically an intermittent rotation, but
Depending on the relationship with the load, this intermittent rotation can actually be made so that the engagement ratio is 1. In other words, since the teeth of the gear are deflected by the load that is applied when the reducer is driven, the period between when one tooth finishes meshing and when the next tooth starts meshing is within the range of tooth deflection. If so, it can be set to 0 using this tooth deflection. In fact, when the theoretical meshing ratio is made slightly smaller than 1, there is a very small gap between when one tooth finishes meshing and when the next tooth starts meshing. That is, 1/
In order to achieve a reduction ratio of about 40, the number of teeth on the external gear should be 39 and the number of teeth on the internal gear should be 40. In this case, the module m = 3 and the pressure angle is If the angle is 30°, the distance will be several microns. This degree of tooth deflection can easily occur when a high load is applied. Therefore, theoretically, the rotation of the reducer is intermittent rotation, but when driving a load, the meshing of one tooth ends and the meshing of the next tooth begins, so in reality, the meshing ratio is reduced to 1. The result will be the same as that of , and the meshing rotation will be smooth. The change in angular velocity is equal to the gap divided by 1 pitch, so it is almost negligible.

(d) If the theoretical engagement ratio is made smaller than 1, the engagement pressure angle can be reduced. The engagement pressure angle α is related to the load acting on the bearing during load transmission, that is, the magnitude of the radial component force F _R. If the component force in the direction tangent to the pitch circle of the load acting perpendicularly to the tooth surface is F, then F _R =
F・tan α, and the smaller α is, the smaller the load acting on the bearing is. Therefore, by reducing the meshing pressure angle α, it is possible to downsize the bearing.

〔Example〕

The embodiment of the present invention shown in FIGS. 1a and 1b will now be described. In the figure, 1 is a main body in which a hydraulic motor 2 is installed. A hub 4 having a flange 5 to which a crawler drive sprocket is attached is rotatably attached to the main body 1 via bearings 1a, 1b, and an internal gear 7 provided on the hub 4
and the external gears 6, 6 form a reduction gear 3.

The speed reducer 3 has an eccentric shaft 50 connected to the output shaft 47 of the hydraulic motor 2 rotatably held between the main body 1 and an end plate 51, and the eccentric shaft 50 has two external gears 6, 6. It is provided via bearings 50a and 50b. Further, on the outer periphery of the end plate 51, a carrier pin 52 passing through the external gears 6, 6 is fixed with a bolt 53 between the end plate 51 and the main body 1. Eight carrier pins 52 are provided as shown in FIG. 1B, and bushes 55 are interposed in the holes 54 of the external gears 6, 6. The two external gears 6, 6 are arranged to mesh with the internal gear 7 at rotational positions 180 degrees apart from each other, so that dynamic balance during rotation can be achieved.

Each of the teeth 6a-1 to 6a-43 of the external gears 6 and 6 and the teeth 7a-1 to 7a-44 of the internal gear 7 has an involute tooth profile and a low tooth profile. The meshing ratio between the internal gear 7 and each external gear 6 is set to 0.5, and the meshing ratio of the teeth of these gears is set to 1 by making the phases of the two sets of meshing positions different by 180 degrees. .

In the reducer with the above configuration, when the eccentric shaft 50 is rotated clockwise, the external gear 6 is restrained from rotating by the carrier pin 52 fixed to the main body, so that the external gear 6 does not rotate and the eccentric shaft is eccentric. It is caused to revolve along a circle whose radius is the amount, and its direction is the same clockwise direction as the eccentric shaft 50. One revolution of the external gear 6 causes the internal gear 7 to rotate clockwise by one tooth pitch.

In the above operation, when the tooth 7a-1 of the internal gear and the tooth 6a-1 of the external gear 6 are meshing, there is a gap between the teeth 6a-2 and 7a-2 that will mesh next. . This gap is determined by the number of teeth of the external gear 6.
In the example with 43 sheets (m=3, pressure angle 30°), the diameter is 4 to 5 microns. Therefore, even if there is a change in the speed of the hub 4, it is extremely small.

Furthermore, even if the tooth 7a-1 or 6a-1 is damaged during load transmission, the next tooth 7a-2 and 6a-2 will mesh with each other, so there is no possibility that the teeth will be damaged one after another due to the load. There isn't.

〔Effect of the invention〕

According to the present invention, the tooth profile of the gear constituting the reducer is an involute curve, and the theoretical meshing ratio is 1.
By making the gear smaller, the meshing pressure angle is kept small and the load acting on the bearing that supports the gear is reduced, so the bearing can be made smaller, and this reduces the overall size of the reducer. Although it is not a general speed reducer, it can be applied to a speed reducer for a traveling device of a crawler vehicle, and has the effect that its traveling drive unit can be made smaller. Furthermore, since the tooth surface pressure during load transmission can be reduced, it is possible to reduce the size accordingly.
In addition, even if the teeth of a gear that meshes with each other are damaged while transmitting a load, the next tooth that meshes with the next one will not be damaged, so the load can move on its own. Effects such as not causing danger can be obtained.

[Brief explanation of the drawing]

FIG. 1a is a longitudinal sectional side view of the main part of an embodiment of the present invention, FIG. 1b is a partial sectional view taken along the line A-A in FIG. 1a, and FIG. Figure 3a is a longitudinal sectional side view of the main parts of another conventional reducer.
Figure b is a partial cross-sectional view taken along line BB in Figure 3a. 1...Body, 2...Hydraulic motor, 3...Reducer, 4...Hub, 5...Flange, 6...External gear, 7...Internal gear, 47...Output shaft, 50...
Eccentric shaft (input shaft).

Claims (1)

[Claims] 1. An eccentric shaft having an eccentric portion connected to the output shaft of the hydraulic motor, which rotatably supports the hub of a crawler drive sprocket having an internal gear on the hydraulic motor body which is installed on the crawler vehicle body side and has a hydraulic motor therein. is rotatably supported on the hydraulic motor body, an external gear meshing with the internal gear is rotatably supported on the eccentric portion of the eccentric shaft via a bearing, and the external gear is rotatably supported on the eccentric portion of the eccentric shaft via a bearing. A plurality of carrier pins are provided that pass through the external gear and have one end fixed to the hydraulic motor main body with a margin between them and the outer periphery of the gear so as to allow the revolution of the gear and suppress its rotation. For a traveling device of a crawler vehicle, in which the tooth profiles of the internal gear and the external gear are formed by an involute curve, the difference in the number of teeth between the internal gear and the external gear is 1, and the theoretical meshing ratio is smaller than 1. Decelerator.