JP2020132016A - Power transmission unit - Google Patents

Abstract

To provide a power transmission unit for enhancing the efficiency of power transmission and braking with a motor as a drive source, and a drum brake as a brake device, and to provide a power transmission unit for a drum brake to efficiently exhibit brake torque.SOLUTION: A power transmission unit 1 comprises: a drive source (100); a first shaft (10) connected to the drive source, and outputting power from the drive source; a second shaft (20) arranged in parallel with the first shaft, and transmitted with the power from the first shaft via a reduction gear pair (200); a third shaft (30) arranged in parallel with the first shaft and the second shaft, and transmitting the power transmitted from the second shaft to drive wheels via a differential mechanism part (400); a fourth shaft (40) connectable to the first shaft via a clutch (300); a drum brake mechanism part (500) arranged on the fourth shaft; and a pair of bearings (510, 520) arranged on the fourth shaft while sandwiching the drum brake mechanism part therebetween.SELECTED DRAWING: Figure 1

Description

The technology disclosed in this application relates to a power transmission unit.

Conventionally, a power transmission unit that transmits power to drive wheels using a motor as at least one drive source, a vehicle or a truck equipped with the power transmission unit, and the like have been known.

Patent Document 1 discloses a power transmission unit for a forklift that transmits the power of the motor to the drive wheels while using the motor as a drive source. Further, it is disclosed that a drum brake is used for the power transmission unit according to Patent Document 1 in order to express the brake torque required when stopping the forklift.

Further, Patent Document 2 discloses that an electromagnetic brake mechanism is provided in a housing of a motor drive unit using a motor as a drive source.

Chinese Patent Application Publication No. 1035228885 Japanese Unexamined Patent Publication No. 2017-145916

However, in the power transmission unit described in Patent Document 1, since the motor as a drive source and the drum brake that produces brake torque are always connected, the power output from the motor is transmitted to the drive wheels of the forklift. At that time, the load of the drum brake is always applied as a drag torque, and there is a problem in the efficiency of power transmission.

Further, in the motor drive unit described in Patent Document 2, since the electromagnetic brake mechanism is used, the power consumption is increased, and as a result of the electromagnetic brake mechanism being housed in the housing, the heat dissipation performance is deteriorated.

Therefore, according to various embodiments, a power transmission unit is provided in which a motor is used as a drive source and a drum brake is used as a braking device to improve power transmission and braking efficiency. Further, the present invention provides a power transmission unit in which the brake torque of the drum brake is efficiently exhibited.

The power transmission unit according to one aspect is arranged in parallel with a drive source, a first shaft connected to the drive source and output power from the drive source, and a reduction gear pair. The second axis through which the power is transmitted from the first axis is arranged parallel to the first axis and the second axis, and is transmitted from the second axis via a differential mechanism unit. A third shaft that transmits the power to the drive wheels, a fourth shaft that can be connected to the first shaft via a clutch, a drum brake mechanism portion provided on the fourth shaft, and the fourth shaft. Above, it is provided with a pair of bearings arranged so as to sandwich the drum brake mechanism portion.

According to the power transmission unit having this configuration, when the power from the drive source is transmitted to the drive wheels of a vehicle or the like, the first shaft and the fourth shaft are disconnected by the clutch, so that the drum brake mechanism is dragged. It is possible to suppress the generation of torque (power loss) and improve the efficiency of power transmission. On the other hand, when braking or stopping a vehicle or the like, the brake torque by the drum brake mechanism can be efficiently contributed to the first shaft by connecting the first shaft and the fourth shaft with a clutch. Since a pair of bearings are arranged on the fourth shaft so as to sandwich the drum brake mechanism portion, it is possible to efficiently suppress the shaking and runout of the drum brake mechanism portion on the fourth shaft. ..

Further, in the power transmission unit according to one aspect, the drive gear in the reduction gear pair is arranged between the drive source and the clutch on the first shaft, and the driven gear in the reduction gear pair is the second. It is preferably arranged on the shaft.

With this configuration, a power transmission unit having a compact configuration can be obtained. Further, the power from the drive source can be efficiently decelerated and transmitted.

Further, in the power transmission unit according to one aspect, a first housing that houses at least the drive source, the reduction gear pair, and the differential mechanism portion, and the drum brake mechanism portion fixed to the first housing are provided. It is preferable to further include at least a second housing for accommodating.

With this configuration, the drum brake mechanism portion is not housed in the first housing, but is housed separately in the second housing, so that the maintenance of the drum brake mechanism portion can be facilitated.

Further, in the power transmission unit according to one aspect, it is preferable that the second housing covers only a part of the drum brake mechanism portion.

With this configuration, the heat dissipation of the drum brake mechanism portion is improved, so that the brake torque by the drum brake mechanism portion can be efficiently exhibited. As a result, the brake torque generated by the drum brake mechanism can be used, for example, at the time of an emergency stop of a vehicle or the like.

Further, in the power transmission unit according to one aspect, one of the pair of bearings is arranged in the first wall portion of the first housing, and the other is arranged in the second wall portion of the second housing. Is preferable.

With this configuration, it is possible to efficiently suppress the sway and runout of the drum brake mechanism portion on the fourth axis.

According to various embodiments, it is possible to provide a power transmission unit that uses a motor as a drive source and a drum brake as a braking device to enhance power transmission and braking efficiency. Further, it is possible to provide a power transmission unit in which the brake torque of the drum brake is efficiently exhibited.

It is the schematic which shows the structure of the power transmission unit which concerns on one Embodiment simply. It is a schematic diagram which enlarges and shows the drum brake mechanism part and the 2nd housing in the power transmission unit which concerns on one Embodiment.

Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings. The same reference numerals are given to the common constituent requirements in the drawings. It should also be noted that the components represented in one drawing may be omitted in another for convenience of explanation. Furthermore, it should be noted that the attached drawings are not always drawn to the correct scale.

1. 1. Configuration of Power Transmission Unit An outline of the overall configuration of the power transmission unit according to one embodiment will be described with reference to FIG. FIG. 1 is a schematic view simply showing the configuration of the power transmission unit 1 according to the embodiment.

As shown in FIG. 1, the basic configuration of the power transmission unit 1 according to one embodiment mainly includes a motor 100 as a drive source, a reduction gear pair 200, a clutch 300, and a differential mechanism unit 400. , The drum brake mechanism 500, the motor shaft 10 as the first shaft for outputting the power from the motor 100, the second shaft 20 as the second shaft arranged parallel to the motor shaft 10, and the motor shaft 10. And an output shaft 30 as a third shaft arranged parallel to the second shaft 20 and transmitting power to a drive wheel (not shown), and a fourth shaft that can be connected to the motor shaft 10 via a clutch 300. The brake shaft 40, the first housing 50, and the second housing 60 are included.

1-1. Motor 100 and motor shaft 10
The motor 100 has, for example, a general configuration in which a rotor (not shown) is arranged at a position facing a stator (not shown), and the rotor rotates around the stator to generate power. Can be used. Further, a motor shaft 10 is connected to the rotor, and the power of the motor 100 is output by the motor shaft 10. It should be noted that the ON / OFF and the number of rotations of the rotation of the motor 100 (rotation of the rotor) are controlled by a separately provided control device (not shown) according to the traveling state and road surface condition of the vehicle on which the power transmission unit 1 is mounted. ) Is controlled.

As the drive source in the power transmission unit 1, not only the motor 100 but also an engine (not shown) used in a general vehicle may be additionally provided. In this case, for example, a structure in which the engine is also connected to the motor shaft 10 can be adopted on the upstream side of the motor 100.

1-2. Reduction gear pair 200 and second shaft 20
As shown in FIG. 1, the reduction gear pair 200 is provided to reduce and increase the power output to the motor shaft 10 and transmit the increased power to the second shaft 20. The drive gear 201 of the reduction gear pair 200 is provided on the motor shaft 10, and the driven gear 202 of the reduction gear pair 200 is provided on the second shaft 20 and meshes with each other.

The drive gear 201 of the reduction gear pair 200 is arranged on the motor shaft 10 between the motor 100 and the clutch 300 described later. With this configuration, the power transmission unit 1 can be made compact as a whole.

1-3. Clutch 300 and brake shaft 40
As shown in FIG. 1, the clutch 300 is provided to connect or disconnect the motor shaft 10 and the brake shaft 40. As the clutch 300, a very general clutch such as a clutch using frictional force or a dog clutch can be adopted.

The operation of the clutch 300 (the operation of connecting or disconnecting the motor shaft 10 and the brake shaft 40) is controlled by a separately provided control device (not shown) according to the vehicle speed or the like. Specifically, when the power from the motor 100 is transmitted to the drive wheels of a vehicle or the like, the motor shaft 10 and the brake shaft 40 are disconnected by the clutch 300. As a result, it is possible to suppress the generation of drag torque (power loss) by the drum brake mechanism unit 500, which will be described later, and improve the efficiency of power transmission from the motor shaft 10 to the drive wheels.

On the other hand, when braking or stopping the vehicle or the like, the motor shaft 10 and the brake shaft 40 can be connected by the clutch 300, and the brake torque by the drum brake mechanism portion 500 can be efficiently contributed to the motor shaft 10. ..

1-4. Differential mechanism unit 400 and output shaft 30
As shown in FIG. 1, when power is transmitted to the final driven gear 26 in the differential mechanism unit 400 that engages with the final drive gear 25 provided on the second shaft 20, the power is transmitted in the differential mechanism unit 400. It is transmitted to the differential gear 401 of the above, and in the differential gear 401, differential control (for example, control of the rotation difference between the left and right wheels) is performed according to an operating condition (straight forward, right / left turn, etc.). The output shaft 30 is connected to the differential gear 401, and the power is distributed to the output shaft 30 based on the above-mentioned differential control, and finally distributed to each drive wheel (not shown). Power is transmitted. As the configuration of the differential mechanism unit 400, a generally known configuration can be adopted.

1-5. Drum brake mechanism 500
As the drum brake mechanism unit 500, a general one that presses the leading shoe 505 and the trailing shoe 506 against the inner surface of the drum 501 to exert the brake torque can be adopted. The operation of the leading shoe 505 and the trailing shoe 506 may be a manual type using a wire or the like, or an automatic type using a motor or the like.

As shown in FIG. 1, the drum brake mechanism portion 500 is preferably provided on the brake shaft 40. In other words, it is preferable to have a configuration in which the brake torque is exerted before the power of the motor 100 is decelerated / increased by the reduction gear pair 200. As a result, the configuration of the drum brake mechanism 500 can be made compact (since the power of the motor 100 has not been decelerated / increased, it is not necessary to increase the size of the drum brake mechanism 500).

By the way, on the brake shaft 40, a pair of bearings 510 and 520 are arranged so as to sandwich the drum mechanism portion 500. This makes it possible to efficiently suppress the sway and runout of the drum brake mechanism portion 500 on the brake shaft 40. The bearing 510 is arranged in the first wall portion 51 of the first housing 50 described later, and the bearing 520 is arranged in the second wall portion 61 of the second housing 60 described later.

1-6. First housing 50
As shown in FIG. 1, the first housing 50 houses at least the motor 100, the reduction gear pair 200, and the differential mechanism unit 400. Further, the first housing 50 may accommodate the clutch 300 inside. As shown in FIG. 1, a part of the motor shaft 10, the second shaft 20, the output shaft 30, and the brake shaft 40 is also housed inside the first housing 50.

The first housing 50 is provided with a third wall portion 52 that supports one end of the second shaft 20. This makes it possible to set the second shaft 20 to the minimum necessary compact length.

Further, as shown in FIG. 1, in the first wall portion 51, the third wall portion 52, and the fourth wall portion 53 in the first housing 50, in addition to the bearing 510 and the bearing 520 described above, the motor shaft 10 A bearing 11 and a bearing 12 for supporting the second shaft 20, a bearing 21 and a bearing 22 for supporting the second shaft 20, and a bearing 31 and a bearing 32 for supporting the output shaft 30 are arranged respectively.

1-7. Second housing 60
As shown in FIG. 1, the second housing 60 accommodates the drum brake mechanism portion 500.

The details of the second housing 60 will be described with reference to FIG. FIG. 2 is an enlarged schematic view showing a drum brake mechanism portion 500 and a second housing 60 in the power transmission unit 1 according to the embodiment.

As shown in FIG. 2, the second housing 60 is fixed to the side surface of the first housing 50.
Then, the drum brake mechanism portion 500 is not housed in the first housing 50, but is housed separately in the second housing 60, so that the maintenance of the drum brake mechanism portion 500 can be facilitated.

Further, the second housing 60 preferably has a substantially U-shaped side surface. As a result, the second housing 60 covers only a part of the drum brake mechanism portion 500, thereby improving the heat dissipation of the drum brake mechanism portion 500.

As described above, one embodiment has been illustrated, but the above embodiment is merely an example and is not intended to limit the scope of the invention. The above-described embodiment can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. In addition, each configuration, arrangement order, shape, size, length, width, thickness, height, number, etc. can be appropriately changed for implementation.

1 Power transmission unit 10 Motor shaft (1st shaft)
20 Second shaft (2nd shaft)
30 Output shaft (3rd axis)
40 Brake shaft (4th axis)
50 1st housing 51 1st wall 60 2nd housing 61 2nd wall 100 Motor (drive source)
200 reduction gear vs. 201 drive gear 202 driven gear 300 clutch 400 differential mechanism 500 drum brake mechanism 510, 520 pair of bearings

Claims (5)

With the drive source
A first shaft that is connected to the drive source and outputs power from the drive source,
A second shaft, which is arranged parallel to the first shaft and whose power is transmitted from the first shaft via a reduction gear pair,
A third axis, which is arranged parallel to the first axis and the second axis and transmits the power transmitted from the second axis to the drive wheels via the differential mechanism unit,
A fourth shaft that can be connected to the first shaft via a clutch,
A drum brake mechanism provided on the fourth shaft and
A pair of bearings on the fourth axis and arranged so as to sandwich the drum brake mechanism portion.
A power transmission unit equipped with. The drive gear in the reduction gear pair is arranged between the drive source and the clutch on the first shaft, and the driven gear in the reduction gear pair is arranged on the second shaft. Power transmission unit. It further includes a first housing that houses at least the drive source, the reduction gear pair, and the differential mechanism, and a second housing that is fixed to the first housing and houses at least the drum brake mechanism. , The power transmission unit according to claim 1 or 2. The power transmission unit according to claim 3, wherein the second housing covers only a part of the drum brake mechanism portion. The power transmission according to claim 3 or 4, wherein one of the pair of bearings is arranged in the first wall portion of the first housing and the other is arranged in the second wall portion of the second housing. unit.

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