JPH0470501B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a speed reducer on which a relatively heavy load is applied, such as for driving a traveling mechanism of a crawler vehicle.

[Conventional technology]

A hydraulic motor with a reduction gear is used as a drive device for the traveling mechanism of a crawler vehicle. This hydraulic motor with a reduction gear needs to have a storage width within the width of the crawler of the traveling mechanism. That is, if the hydraulic motor equipped with a speed reducer is larger than the width of the crawler, it will be more likely to be hit by rocks or the like while traveling, causing problems such as damage to the hydraulic motor.

Therefore, in order to reduce the size of a hydraulic motor equipped with a reduction gear, it is possible to reduce the size of the hydraulic motor and to reduce the size of the reduction gear. In order to downsize a hydraulic motor, it can be designed to have low torque and high rotational speed. Therefore, when using a hydraulic motor with small torque and high rotational speed, a reduction gear with a large reduction ratio is required. In order to reduce the size of this speed reducer, it is necessary to reduce the number of gears used for speed reduction.

Based on this idea, the reduction gear shown in FIGS. 2a and 2b (Japanese Patent Application Laid-open No. 163725/1983) was proposed. Second
The reducer shown in Figures a and b has a hydraulic motor (not shown) installed in a main body 1 attached to a body 2 of a vehicle, and internal teeth 3 formed by pins as shown in Figure 2b. A hub 4 and an input shaft 5 connected to a hydraulic motor are rotatably attached. A pinion 8 having teeth 6 that mesh with internal teeth 3 of the hub 4
is supported by an eccentric shaft 9 fixed to the main body 1. A gear 11 is fixed to the tip of the eccentric shaft 9, and the eccentric shaft 9 is connected to the input shaft 5 via a gear 10 that meshes with the gear 11. The eccentric shaft 9 is supported at both ends by bearings 14a and 14b between an end plate 12 fixed to a convex portion 13 of the main body 1 and the main body 1, and between both supported parts between the end plate 12 and the main body 1. Eccentric portions 15a and 15b are provided in which the directions of eccentricity e are different from each other by 180 degrees, and the pinion 8
Bearings 16 are attached to these eccentric parts 15a and 15b.
It is attached via a and 16b. Note that, as shown in FIG. 2b, three eccentric shafts 9 are provided, but the other two have the same structure as the eccentric shafts 9 described above.

In the reducer having the above configuration, the rotation applied to the input shaft 5 is reduced through the gears 10 and 11,
The eccentric shaft 9 is rotated. This rotation of the eccentric shaft 9 causes the pinions 8, 8 to oscillate and rotate, and as a result, the hub 4 divides the difference in the number of teeth between the pinion 8 and the number of teeth of the internal teeth 3 by the number of teeth of the internal teeth 3. The input shaft 5 rotates in the same direction as the rotation direction of the input shaft 5.

[Problem that the invention seeks to solve]

The speed reducer having the above structure has the following problems when used in a crawler vehicle traveling device.

(a) Since the eccentric shaft 9 is supported by the main body 1 and the end plate 12, the structure in which the input shaft 5 and the eccentric shaft 9 are connected by the gears 10 and 11 causes the following two problems. A point occurs.

Part 1 is gears 10 and 11 in front of the differential speed reduction mechanism (speed reduction mechanism using pinion 8 and internal gear).
Since the speed is decelerated by , the amount of backlash is large. In other words, the breakdown is gear 10
This is because it exists both in the meshing part between and 11 and in the meshing part of the gears of the differential reduction gear. For this reason, when the crawler vehicle is switched from forward to reverse, a large impact occurs due to the large amount of backlash.

Part 2 is that in the configuration (a) above, the eccentric shaft 9
It is necessary to insert bearings between the main body 1, the end plate 12, and the pinion 8. Bearings have a limited lifespan, and the more bearings there are between the input shaft and the output shaft, the shorter the lifespan of the reducer will be. (Time life is the probability of failure within a given time when operating with a given load.) Therefore, in order to obtain sufficient life, the load capacity (load that can be carried) of the bearing should be increased. Therefore, it is necessary to use larger bearings. For this reason, it is impossible to avoid increasing the size.

(b) Since the teeth 3 of the internal gear are formed by pins, the tooth profile of the external gear 8 is a pericycloid parallel curve, which is the envelope of a circle formed by the pins.

A pericycloid curve is a curve formed by the center of a pin when rotating a circle that is eccentric by a predetermined value from the center of the internal gear in an internal gear having internal teeth formed by a pin. ,
The tooth profile of the external gear of the conventional reduction gear described above uses a curve parallel to the pericycloid curve, and is further provided with a backlash so that it can rotate when a load is applied to the reduction gear.

For the operation of this speed reducer, the number of teeth that mesh with the internal teeth is plural (approximately half of the number of external teeth mesh with each other). However, since the tooth profile of the external teeth is a circular envelope, it is difficult to obtain sufficient machining accuracy, and the number of engagements decreases due to errors and deflection during load transmission.

The load acting on the bearing of the eccentric shaft of this reducer is a combination of the force from the carrier pin and the force acting from the meshing point of the meshing teeth in the direction of the intersection of the base circles of the external gear and internal gear. It is determined by the relationship. Therefore, when transmitting a predetermined load, if the number of meshing teeth is a predetermined number, the transmitted load does not change, and if the number of meshing teeth decreases, the force in the direction of the intersection of the base circles increases, The radial load acting on the bearing also increases.

Furthermore, if the number of meshes during load transmission decreases, the number of teeth that share the load decreases, and therefore the load acting on the tooth surface increases.

As mentioned above, even if the same load is applied to each of multiple reducers, the number of meshes during operation remains constant depending on the accuracy and overall strength (rigidity) of the reducer. However, there is a large variation in lifespan.

Therefore, the purpose of improving this drawback is to:
A technology to eliminate changes in the number of meshes during load transmission was proposed in Japanese Patent Publication No. 55-21224. This tooth profile is called a circular arc tooth profile, and is intended to utilize only the circular arc portion of the above-mentioned pericycloid tooth profile.

If this tooth profile is designed to reduce the meshing pressure angle, the meshing with the pin gear will become closer to edge contact, and the strength of the gear will decrease. In order to avoid this drawback, the diameter of the arc of the arc tooth profile is increased, and the meshing point between the pin gear and the arc is moved away from the edge of the arc. For this reason, the meshing pressure angle becomes large and the backlash also becomes large. As the engagement pressure angle increases,
As the radial load acting on the bearing increases and the backlash increases, the impact at the time of switching from forward rotation to reverse rotation increases accordingly, and the amount of retreat when stopping the uphill climb increases.

[Means for solving problems]

The means of the present invention is such that a hub having an internal gear is rotatably attached to a main body to which a hydraulic motor is attached, and an input shaft connected to the hydraulic motor and having an eccentric portion is rotatably provided, and the eccentricity of the input shaft is A traveling device for a crawler vehicle, wherein an external gear meshing with the internal gear is rotatably attached to the part, and a plurality of carrier pins parallel to the input shaft are respectively passed through the external gear and one end thereof is fixed to the main body. In the reduction gear for use, the tooth profile of the internal gear and the external gear are involute tooth profile, the difference in the number of teeth between both gears is one tooth, and the gear is integrally connected to the main body across the other end of each of the carrier pins. Further, a support block is provided to rotatably support the input shaft together with the main body, and a bush is provided in each of the external gear penetrating portions of the carrier pin.

[Effect]

In the reducer of the present invention, the rotation of the hydraulic motor is converted into the oscillating rotation of the external gear via the input shaft at its eccentric portion, and when the external gear is oscillated and rotated,
Since the carrier pin is fixed to the main body, the internal gear rotates at a reduced speed.

This reducer has an eccentric part on the input shaft, and there are no intermediate gears other than external gears and internal gears, so only one backlash is required.
It's a place. In addition, the tooth profile of the gear is an involute tooth profile, and this involute tooth profile is different from other tooth profiles (pericycloid parallel curve and circular arc tooth profile).
The curve is a circular envelope, whereas it is a straight envelope. Therefore, when machining the tooth profile, the manufacturing error of the tooth profile is reduced. The load acting on the tooth surface during load transmission is stable and can be made small. In addition, in order to avoid convex-to-convex engagement and edge contact, there is no need to change the engagement pressure angle, and it can be set to the minimum necessary value. Therefore, the load acting on the bearing can be reduced, and there is almost no change in the pressure angle with respect to deflection during load transmission, so
The load acting on the bearing can be stabilized.

Furthermore, this reducer has a structure in which the carrier pin is held by a support block and a bush is provided between the external gear and the carrier pin, so that loads, slips, etc. acting on each part can be reduced. In other words, when the internal gear and external gear of this reducer engage and rotate, the load that acts on the carrier pin is equal to the length of the cosine of the line connecting the center of the carrier pin and the center of the input shaft. A proportional load acts whose direction is a cosine, but
Since the tip of the carrier pin is held by the support block, the load is distributed and the stress acting on the carrier pin can be reduced. Since the bush is interposed between the carrier pin and the external gear, oil films can be interposed between the carrier pin, the bush, and the external gear, respectively. When the speed reducer is in operation, rolling and sliding can occur together between the carrier pin and the external gear. For this reason, it is possible to reduce slippage compared to a type without a bushing, and the contact area between the carrier pin and the bushing is large, so it is possible to reduce slippage during operation. The Hertzian stress can be reduced to a low value.

Furthermore, by setting the difference in the number of teeth between the internal gear and the external gear to 1 to a degree that does not cause trochoidal interference, the theoretical meshing ratio of both gears will be about 0.4, but The gap between the teeth is several microns. This gap becomes smaller as the number of teeth increases. Therefore, when the teeth are slightly bent, the two teeth will mesh with each other. At this time, a speed change occurs in the ratio of the gap to one pitch, but since the gap is small, the value is extremely small. Therefore, in reality, the engagement ratio is approximately 1, and the sliding length is approximately 1.
It becomes pitchy. Note that it is theoretically possible to set the meshing ratio to 1, but in order to do so, the difference in the number of teeth must be 2.
It is necessary to use ~3 teeth, and in this case, the maximum number of meshing teeth is 3, and the sliding length increases.
This is not preferred because it requires an intermediate speed reduction device to obtain a high speed reduction ratio.

〔Example〕

In FIG. 1a and FIG. 1b, 1 is a main body, which is provided with a hydraulic motor 21, a hub 20 and an input shaft 23 connected to a shaft 22 of the hydraulic motor 21, which are rotatably provided, and a carrier pin 25. , 25a~2
Bolts 32, 32a to 32h that fix 5h are screwed in. A lid 26 is provided at the end of the hub 20, and the hub 20, lid 26, and main body 1 form an oil chamber 2.
7 is formed. The hub 20 has an external gear 3
It has an internal gear 28 in which gears 0 and 31 mesh, and a flange 29 to which a sprocket is fixed.

The input shaft 23 is provided with an eccentric portion 24, and external gears 30, 31 are rotatably fitted into the eccentric portion 24. In addition, the eccentric part 24
is supported by the main body 1 and the support block 33 via bearings 40 and 41. There are eight carrier pins 25a to 25 as shown in FIG. 1b.
h, each of which passes through the external gears 30 and 31, is supported by the support block 33 and the main body 1, and is fixed to a bolt 32,
Through holes 35, 35a of the external gears 30 and 31
- 35h, bushes 37, 37a - 3
7h is provided.

The difference in the number of teeth between the internal gear 28 and the external gears 30 and 31 is one, and the tooth profile is an involute tooth profile, and the teeth are low enough not to cause trochoidal interference during meshing rotation. In addition, external gears 30, 3
1 is an eccentric amount δ as shown in FIG. It is designed to maintain balance when rotating.

In FIG. 1b, when the rotational force in the direction of arrow c is transmitted to the input shaft 23, the external gears 30 and 31 are oscillated and rotated in the direction shown by arrow d, and the hub 20 is rotated in the direction of arrow e. do.

〔Effect of the invention〕

In the present invention, since the gears mesh at one location, only one location is required for backlash, and since the tooth profile is an involute curve, the amount of backlash can be reduced. . Therefore, the impact at the time of switching from normal rotation to reverse rotation can be reduced and the maneuverability of the crawler vehicle can be improved.

In addition, by stabilizing the load acting on the tooth surface of the gear and reducing the number of time-life parts, the quality of each product is made uniform and reliability is improved.

Furthermore, since the load is distributed, it is possible to downsize the device.

[Brief explanation of drawings]

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. Second
FIG. b is a partial cross-sectional view taken along line B-B in FIG. 2a. 1...Main body, 20...Hub, 21...Hydraulic motor, 2
2... Hydraulic motor shaft, 23... Input shaft, 24... Eccentric part, 25, 25a to 25h... Carrier pin, 26
...Lid, 27...Oil chamber, 28...Internal gear, 29...Flange, 30, 31...External gear, 32...Bolt, 3
3... Support block, 35, 35a to 35h... Through hole, 37, 37a to 37h... Bush.

Claims (1)

[Claims] 1. A hub having an internal gear is rotatably attached to a main body to which a hydraulic motor is attached, and an input shaft connected to the hydraulic motor and having an eccentric part is rotatably provided, and the eccentric part of the input shaft has the internal gear. In a speed reducer for a traveling device of a crawler vehicle, an external gear meshing with a gear is rotatably mounted, and a plurality of carrier pins parallel to the input shaft are respectively passed through the external gear and one end thereof is fixed to the main body. , the tooth profile of the internal gear and the external gear is an involute tooth profile, and the difference in the number of teeth between both gears is one tooth,
A support block is provided over the other end of each of the carrier pins and is integrally connected to the main body and rotatably supports the input shaft together with the main body, and a bush is provided in each of the external gear penetrating portions of the carrier pin. Reducer for traveling equipment of crawler vehicles.