EP4610140A1

EP4610140A1 - Truck

Info

Publication number: EP4610140A1
Application number: EP24796491.9A
Authority: EP
Inventors: Masaya Kawano; Toshikazu Hayashi; Koshi TANIMOTO; Yukihide Yanobu; Masafumi NAKAKUBO
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 2023-04-28
Filing date: 2024-02-01
Publication date: 2025-09-03
Also published as: WO2024224732A1; EP4610140A4; JP2024158744A

Abstract

In this truck having a structure in which a motor is directly connected to an axle via a joint, a displacement allowance required for a joint unit is reduced while suppressing an increase in an unspring weight. The truck comprises: a truck frame; an axle including a non-rotary unit that supports the truck frame via an axle spring; a drive unit including a hollow-shaped motor through which the axle is inserted, and a motor bracket which holds the motor and which is supported by the truck frame in a relatively movable state in the upward direction; a joint unit that connects the motor and the axle so as to be capable of transmitting power; and a guide unit that is provided to the non-rotary unit, that abuts against the drive unit when the truck frame is displaced by a prescribed amount or more with respect to the axle, and that restricts the displacement of the drive unit with respect to the axle.

Description

Technical Field

The present disclosure relates to a truck.

Background Art

In a truck of a railway vehicle, a technique is known in which a hollow structure motor through which an axle is inserted directly drives the axle via a joint (so-called direct drive system). For example, a truck to which such a technique is applied is disclosed in PTL 1 below.
PTL 1 discloses a truck including a hollow shaft of a main motor (motor), an axle that penetrates the hollow shaft and that has wheels mounted on both end portions, and a joint device that connects the hollow shaft and the axle. The main motor is supported by the axle via the joint device. The joint device is configured with an elastic joint capable of adjusting a positional deviation occurring between a central axis of the hollow shaft and a central axis of the axle.

Citation List

Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No. 2005-59616

Summary of Invention

Technical Problem

As in PTL 1, the truck having a structure in which a weight of the motor connected to the axle via the joint is supported by the axle has a problem in that an unsprung weight (weight below an axle spring) increases. Therefore, it is conceivable that the motor is attached to a truck frame above the axle spring. When a load of the motor is supported by the truck frame above the axle spring, an unsprung load decreases accordingly.
However, in a case where the motor is attached to the truck frame, for example, the motor is relatively displaced with respect to the axle due to relative displacement of the truck frame with respect to the axle, and thus it is necessary to absorb the relative displacement by a joint unit. Therefore, a displacement allowance (magnitude of allowable relative displacement) required for the joint unit becomes excessive. Therefore, even in a case where the direct drive system is adopted, it is desirable to reduce the displacement allowance required for the joint unit while suppressing an increase in the unsprung weight.
The present disclosure is made to solve the above-described problems, and an object of the present disclosure is to provide a truck capable of reducing a displacement allowance required for a joint unit while suppressing an increase in an unsprung weight in a truck having a structure in which a motor is directly connected to an axle via a joint. Solution to Problem
A truck of the present disclosure for achieving the above object includes a truck frame, an axle including a non-rotary unit that supports the truck frame via an axle spring, a drive unit including a hollow-shaped motor through which the axle is inserted, and a motor bracket that holds the motor and is supported by the truck frame in a state of being relatively movable in an upward direction, a joint unit that connects the motor and the axle to be capable of transmitting power, and a guide unit that is provided on the non-rotary unit and that abuts against the drive unit to restrict displacement of the drive unit with respect to the axle when the truck frame is displaced by a prescribed amount or more with respect to the axle.

Advantageous Effects of Invention

According to the truck of the present disclosure, it is possible to reduce a displacement allowance required for a joint unit while suppressing an increase in an unsprung weight in a truck having a structure in which a motor is directly connected to an axle via a joint.

Brief Description of Drawings

Fig. 1 is a schematic front view showing a truck of a first embodiment.
Fig. 2 is an explanatory view showing a state where a truck frame in Fig. 1 is displaced.
Fig. 3 is a schematic view showing a structural example of a vicinity of an upper end portion of a guide unit.
Fig. 4 is an explanatory view showing a first attachment example of the guide unit to a non-rotary unit of an axle.
Fig. 5 is an explanatory view showing a second attachment example of the guide unit to the non-rotary unit of the axle.
Fig. 6 is a schematic view for describing a configuration of a motor bracket and a truck frame in a truck of a second embodiment.
Fig. 7 is an explanatory view showing a state where the truck frame in Fig. 6 is displaced.
Fig. 8 is a schematic view for describing a configuration of a truck frame in a truck of a third embodiment.
Fig. 9 is an explanatory view showing a state where the truck frame in Fig. 8 is displaced.
Fig. 10 is a schematic view showing a truck according to a first modification example.
Fig. 11 is a schematic view showing a truck according to a second modification example.

Description of Embodiments

Hereinafter, a preferred embodiment of the present disclosure will be described in detail with reference to the drawings. The present disclosure is not limited to the embodiment. In addition, in a case where there are a plurality of embodiments, the present disclosure also includes configurations obtained by combining each embodiment. In addition, components in the embodiments include those which can be easily assumed by those skilled in the art, those which are substantially the same, and those which have a so-called equivalent scope.

[First Embodiment]

Fig. 1 is a schematic front view showing a truck of a first embodiment, and Fig. 2 is an explanatory view showing a state where a truck frame is displaced. In the following description, the vertical direction is the upward-downward direction of a truck 10, the traveling direction of the truck 10 is the forward-rearward direction, and the direction orthogonal to the traveling direction in the horizontal plane is the width direction of the truck 10.
The truck 10 of the first embodiment is, for example, a truck (traveling device) for a railway vehicle. The truck 10 travels on a pair of rails RA that configure a railway track. The truck 10 is disposed below a vehicle body 100 (refer to a dashed double-dotted line portion) of the railway vehicle and supports the vehicle body 100 from below. A space for boarding and alighting of an occupant is provided inside the vehicle body 100.

The truck 10 includes a truck frame 20, an axle 30, a drive unit 40, a joint unit 50, and a guide unit 60.
The truck frame 20 is a frame body in which each component of the truck 10 is assembled. The truck frame 20 includes, for example, a pair of side beams 21 and a cross beam 22 connecting the pair of side beams 21. The pair of side beams 21 extend along the forward-rearward direction and are disposed at an interval in the width direction. The cross beam 22 extends in the width direction, and both ends of the cross beam 22 are connected to each of the pair of side beams 21. The truck frame 20 is mainly formed to extend in a horizontal direction. The truck frame 20 has a vehicle body support portion 23 such as a bolster spring on an upper surface side, and supports the vehicle body 100 via the vehicle body support portion 23.
The axle 30 is a rotary shaft member disposed below the truck frame 20 and extending in the width direction. Wheels 31 are provided at both ends of the axle 30. The truck 10 travels as each wheel 31 rotates on the rail RA with the rotation of the axle 30.
The axle 30 supports the truck frame 20 from below. Specifically, the axle 30 includes a non-rotary unit 32 that supports the truck frame 20 via an axle spring 33. The non-rotary unit 32 is a bearing housing that accommodates a bearing that rotates and supports the axle 30. One pair of the non-rotary units 32 are provided near both end portions of the axle 30, and the axle 30 is inserted through the non-rotary units 32. The axle spring 33 is provided on an upper portion of each non-rotary unit 32, and the truck frame 20 is supported on the axle spring 33. Although not shown, the axle 30 is provided at least one in each forward-rearward direction of the truck frame 20.
The axle spring 33 is an elastic member that can be elastically deformed in the upward-downward direction, and is, for example, a compression coil spring. The axle spring 33 alleviates the relative vibration between the truck frame 20 and the axle 30 in the upward-downward direction. When the weight of the vehicle body 100 changes due to the boarding and alighting of the occupants, the axle spring 33 is elastically deformed in response to the load. In this manner, the truck frame 20 is displaced up and down with respect to the axle 30. In addition, while the truck 10 travels, the wheels 31 and the axle 30 are displaced up and down following undulations of the rail RA, and the axle spring 33 is elastically deformed in response to the displacement.
The drive unit 40 includes a motor 41 and a motor bracket 42. In Fig. 1, the internal structure of the motor 41 is shown in a cross section for convenience.
The motor 41 is provided at a position below the truck frame 20 and between both ends of the axle 30. The motor 41 has a hollow shape, and the axle 30 is inserted through a hollow portion of the motor 41. The motor 41 is a so-called direct drive system motor, and directly drives the axle 30 via the joint unit 50 without the use of a speed reducer.
The motor 41 includes a stator 41a, a rotor 41b, and a bearing 41c. The stator 41a is formed in a cylindrical shape with a central axis thereof aligned along the axis of the axle 30. The rotor 41b is provided on the radial inner side of the stator 41a. The rotor 41b is formed in a cylindrical shape with a central axis thereof aligned along the axis of the axle 30, similarly to the stator 41a. The rotor 41b is provided to be rotatable around the central axis by the bearing 41c. The rotor 41b is connected to the joint unit 50 at an axial end portion. The motor 41 rotates the rotor 41b around the central axis in accordance with power supply.
The motor bracket 42 is a holding member that holds the motor 41, and is connected to an outer peripheral surface (upper surface) of the motor 41. The motor bracket 42 is supported by the truck frame 20 in a state of being relatively movable in the upward direction. The motor bracket 42 includes a support plate portion 43 extending in the horizontal direction and a connection portion 44 extending downward from the lower surface of the support plate portion 43 and connected to the motor 41. The support plate portion 43 is placed on a support surface SF of the truck frame 20. In the example of Fig. 1, the support surface SF is the upper surface of the truck frame 20 (upper surface of the side beam 21). That is, the motor bracket 42 is supported from below by the truck frame 20 (side beam 21) at both end portions of the support plate portion 43 in the width direction. The connection portion 44 passes through a space between the pair of side beams 21 of the truck frame 20 and is connected to the motor 41. The motor bracket 42 (support plate portion 43) is movable in the upward direction and can be separated from the upper surface of the truck frame 20.
In this way, in the first embodiment, the motor 41 is supported in a state of being suspended from the truck frame 20 via the motor bracket 42. In a state where the motor bracket 42 is in contact with the upper surface of the truck frame 20 without being separated from the upper surface, the motor 41 is relatively displaced with respect to the axle 30 in the upward-downward direction in an integrated manner with the truck frame 20.
The joint unit 50 connects the motor 41 and the axle 30 to be capable of transmitting power. The joint unit 50 is disposed between the motor 41 and the non-rotary unit 32 on one side (right side in Fig. 1) in the width direction. The joint unit 50 includes an annular axle-side member 51 and a coupling 52. The axle-side member 51 is fixed to the axle 30 in a state where the axle 30 is inserted through the inner peripheral side. An outer peripheral portion of the axle-side member 51 faces an end surface of the rotor 41b in a central axis direction (width direction of the truck 10) and is connected to the rotor 41b via the coupling 52. In this manner, the joint unit 50 transmits the rotation of the rotor 41b to the axle 30.
The coupling 52 is formed to be elastically deformable. The joint unit 50 can absorb the relative displacement of the drive unit 40 (motor 41) with respect to the axle 30 by elastically deforming the coupling 52. That is, the joint unit 50 can transmit the power even in a state where the central axis position of the motor 41 is displaced from the central axis position of the axle 30. In the first embodiment, the guide unit 60 is provided so that the relative displacement of the drive unit 40 (motor 41) with respect to the axle 30 does not exceed the displacement allowance of the joint unit 50. The displacement allowance of the joint unit 50 means an allowable value of the magnitude of the deviation between the central axis position of the motor 41 and the central axis position of the axle 30 in the upward-downward direction.
The guide unit 60 is provided in the non-rotary unit 32 of the axle 30. The guide unit 60 abuts against the drive unit 40 to restrict the displacement of the drive unit 40 with respect to the axle 30 when the truck frame 20 is displaced by a prescribed amount PA or more with respect to the axle 30.
The guide unit 60 is provided in each of the non-rotary units 32. The configurations of the respective guide units 60 are the same. The guide unit 60 is provided on a side surface of each of the non-rotary units 32 on a central side (motor 41 side) of the truck 10 in the width direction. The guide unit 60 is a columnar or plate-shaped member extending upward from the non-rotary unit 32. The guide unit 60 extends to a predetermined position in the vicinity of the lower surface of the motor bracket 42 (support plate portion 43) through the inside of the pair of side beams 21 of the truck frame 20. That is, the guide unit 60 is provided such that the interval between an upper end portion 61 of the guide unit 60 and the motor bracket 42 (support plate portion 43) in the upward-downward direction is the prescribed amount PA.
In this manner, for example, when the truck frame 20 is displaced downward by more than the prescribed amount PA with respect to the axle 30 due to the boarding of the occupant, the guide unit 60 abuts against the lower surface of the motor bracket 42 (support plate portion 43) on the truck frame 20 to restrict (prevent) the downward displacement of the motor bracket 42. As a result, in a state where the truck frame 20 is displaced downward by more than the prescribed amount PA, as shown in Fig. 2, the guide unit 60 supports the entire drive unit 40 including the motor bracket 42 from below, and the support plate portion 43 of the motor bracket 42 is separated from the support surface SF of the truck frame 20 by an interval CL. For this reason, the guide unit 60 limits the relative displacement of the drive unit 40 (motor bracket 42 and motor 41) with respect to the axle 30 in the upward-downward direction to within the prescribed amount PA in Fig. 1 regardless of the displacement amount of the truck frame 20.
The prescribed amount PA is smaller than the displacement allowance of the joint unit 50 in the upward-downward direction. Therefore, even in a case where the motor 41 is displaced up and down due to the relative displacement between the truck frame 20 and the axle 30, the displacement amount of the central axis of the motor 41 with respect to the central axis of the axle 30 is limited to the prescribed amount PA, which is less than the displacement allowance of the joint unit 50.
The prescribed amount PA may be zero. In this case, the upper end portion 61 of the guide unit 60 is disposed at a height position substantially the same as the height position of the support surface SF (upper surface) of the truck frame 20 in the reference state shown in Fig. 1. In this case, the upper end portion 61 of the guide unit 60 can be provided in a state of being in contact with the motor bracket 42 that is not displaced. Here, the reference state of the truck frame 20 is, for example, a state (state where no occupant is on board) where the truck 10 is assembled into the railway vehicle and the weight of the vehicle body 100 other than the occupant acts on the truck frame 20. The displacement amount of the truck frame 20 is defined as the displacement amount from the reference state, and is zero in the reference state.
In the first embodiment, the prescribed amount PA is nonzero. The guide unit 60 is provided at a position at which the guide unit 60 is not in contact with the drive unit 40 (the support plate portion 43 of the motor bracket 42) when the displacement of the truck frame 20 with respect to the axle 30 is less than the prescribed amount PA. That is, a gap of the prescribed amount PA (refer to Fig. 1) is provided between the upper end portion 61 of the guide unit 60 and the motor bracket 42.
With such a configuration, in the reference state shown in Fig. 1, the weight of the drive unit 40 (motor bracket 42 and motor 41) acts on the axle 30 via the truck frame 20 and via the axle spring 33. That is, since the weight of the drive unit 40 is excluded from the "unsprung weight" which is the weight below the axle spring 33, the unsprung weight is reduced, for example, as compared with a case where the drive unit 40 is directly supported by the axle 30.
In a state where the guide unit 60 supports the motor bracket 42 (drive unit 40) as shown in Fig. 2, the weight of the drive unit 40 is supported by the axle 30 via the guide unit 60 (without the interposition of the axle spring 33). Therefore, the weight of the drive unit 40 is included in the unsprung weight.

Fig. 3 is a schematic view showing a structural example of a vicinity of the upper end portion 61 of the guide unit 60.
As shown in Fig. 3, the guide unit 60 may include an abutment member 62 that is provided to be inclinable in any direction. Specifically, the guide unit 60 may be provided with a spherical-shaped (hemispherical-shaped) sliding portion 63. The abutment member 62 has a spherical seat (spherical recessed portion) 64 that is fitted to the sliding portion 63. The abutment member 62 is inclined in any direction by the sliding between the spherical seat 64 and the sliding portion 63. Accordingly, even when the motor bracket 42 (support plate portion 43) is inclined with respect to and abuts against the guide unit 60, the abutment member 62 can be inclined to be in surface contact with the motor bracket 42 in accordance with the inclination of the motor bracket 42, and thus a stable contact state can be ensured.
In addition, as in the structural example of Fig. 3, the truck frame 20 may include a guide member 24 that guides the relative displacement between the guide unit 60 and the truck frame 20. The guide member 24 is fixed to the side beam 21 of the truck frame 20, for example. The guide member 24 has a tubular shape facing the upward-downward direction, and the guide unit 60 is slidably inserted into the guide member 24. The guide member 24 supports the guide unit 60 such that the guide unit 60 does not deviate in position or incline in the horizontal direction while allowing the relative up-down displacement between the truck frame 20 and the guide unit 60 (axle 30).
In addition, the non-rotary unit 32, the truck frame 20, and the motor bracket 42 may be provided with a bush, a guide groove, or the like that supports the guide unit 60.
Fig. 4 is an explanatory view showing a first attachment example of the guide unit 60 to the non-rotary unit 32 of the axle 30. Fig. 5 is an explanatory view showing a second attachment example of the guide unit 60 to the non-rotary unit 32 of the axle 30.
In the example of Fig. 4, one guide unit 60 is attached to one non-rotary unit 32. A lower end portion of the guide unit 60 is fixed to the axial side surface of a housing 32a of the non-rotary unit 32. The non-rotary unit 32 supports the guide unit 60 at a position directly above the axle 30 (on a vertical line passing through the central axis of the axle 30).
Fig. 5 shows an example in which a plurality of (two) guide units 60 are attached to one non-rotary unit 32. In the example of Fig. 5, the non-rotary unit 32 has a pair of attachment portions 32b and 32c that each protrude forward and rearward from the housing 32a. The attachment portions 32b and 32c each support the lower end portion of one guide unit 60.

[Second Embodiment]

Fig. 6 is a schematic view for describing a configuration of a motor bracket 42A and a truck frame 20A in a truck 10A of a second embodiment. Fig. 7 is an explanatory view showing a state where the truck frame 20A in Fig. 6 is displaced. In the second embodiment, since the structure is the same as that of the first embodiment except for the structures of the motor bracket 42A and the truck frame 20A, description thereof will be omitted. In addition, the members having the same functions as in the above-described first embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.
The truck 10A according to the second embodiment further includes a first biasing member 70 that biases the drive unit 40 toward the guide unit 60 in a state where the drive unit 40 and the guide unit 60 abut against each other.
The first biasing member 70 is a compression coil spring in Fig. 6. The first biasing member 70 may be an elastic body such as rubber or a cushion. The first biasing member 70 is provided in a compressed state between the head of a fixing bolt 71 and the upper surface of the motor bracket 42A. In Fig. 6, the first biasing members 70 are provided on both sides (that is, both side beams 21) of the truck frame 20A in the width direction.
The fixing bolt 71 is inserted through the inside of the first biasing member 70. The fixing bolt 71 passes through a through-hole 45 formed in the motor bracket 42A and is engaged with a screw hole 25 formed in the support surface SF of the truck frame 20A, thereby being fixed to the truck frame 20A. The through-hole 45 penetrates the support plate portion 43 in the upward-downward direction. The inner diameter of the through-hole 45 is larger than the outer diameter of the shaft portion of the fixing bolt 71 and smaller than the outer shape of the head of the fixing bolt 71. Therefore, the motor bracket 42A can be displaced in the upward-downward direction between the support surface SF, which is the upper surface of the truck frame 20A, and the head of the fixing bolt 71. A bush or the like having high slidability and wear resistance may be provided between the inner peripheral surface of the through-hole 45 and the outer peripheral surface of the shaft portion of the fixing bolt 71.
The first biasing member 70 biases the drive unit 40 (motor bracket 42A) downward toward the support surface SF of the truck frame 20A. The first biasing member 70 applies a biasing force F1 downward toward the support surface SF of the truck frame 20A, to the motor bracket 42A. The first biasing member 70 suppresses the motor bracket 42A from being separated from the support surface SF of the truck frame 20A by the biasing force F1 with respect to the vibration during the traveling of the truck 10A. A spacer may be provided between the first biasing member 70 and the motor bracket 42A to increase the compression amount of the first biasing member 70.
Here, as shown in Fig. 7, it is assumed that the truck frame 20A is displaced downward by the prescribed amount PA or more with respect to the axle 30 (refer to Fig. 1). The displacement of the drive unit 40 (motor bracket 42A and motor 41) is restricted by the motor bracket 42A abutting against the guide unit 60. The first biasing member 70 biases the drive unit 40 downward toward the guide unit 60 in a state where the drive unit 40 is supported (restricted) by the guide unit 60.
That is, when the truck frame 20A is displaced downward, the guide unit 60 forms the interval CL between the motor bracket 42A and the support surface SF of the truck frame 20A. The first biasing member 70 is compressed in response to the interval CL, and biases the motor bracket 42A against the guide unit 60 with a biasing force F2 corresponding to the compression amount. The first biasing member 70 suppresses the motor bracket 42A from being separated from the guide unit 60 by the biasing force F2 even in a case where the guide unit 60 vibrates up and down due to the vibration transmitted from the wheels 31 during the traveling of the truck 10A. In this manner, the first biasing member 70 suppresses the vibration of the motor 41 with respect to the axle 30.

[Third Embodiment]

Fig. 8 is a schematic view for describing a configuration of a truck frame 20B in a truck 10B of a third embodiment. Fig. 9 is an explanatory view showing a state where the truck frame 20B in Fig. 8 is displaced. In the third embodiment, since the structure is the same as that of the second embodiment except for the structure of the truck frame 20B, description thereof will be omitted. In addition, the members having the same functions as in the above-described second embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.
The truck 10B according to the third embodiment further includes a second biasing member 80. The second biasing member 80 is provided between the truck frame 20B and the motor bracket 42A and biases the motor bracket 42A in the upward direction away from the support surface SF of the truck frame 20B.
The second biasing member 80 is a compression coil spring in Fig. 8. The second biasing member 80 may be an elastic body such as rubber or a cushion. The second biasing member 80 is provided in a compressed state between the lower surface of the motor bracket 42A and the upper surface of the truck frame 20B. In Fig. 8, the second biasing members 80 are provided on both sides (both side beams 21) of the truck frame 20B in the width direction.
Specifically, a recessed portion 26 for accommodating the second biasing member 80 is formed on the upper surface (support surface SF) of the truck frame 20B. The second biasing member 80 is disposed in the recessed portion 26, and the shaft portion of the fixing bolt 71 is inserted into the second biasing member 80. The screw hole 25 for fixing the fixing bolt 71 is formed on the bottom surface of the recessed portion 26.
In this manner, the second biasing member 80 applies a biasing force F3 in the upward direction away from the support surface SF of the truck frame 20B, to the motor bracket 42A. In the reference state shown in Fig. 8, the biasing force F3 of the second biasing member 80 is smaller than the biasing force F1 of the first biasing member 70. The motor bracket 42A is pressed against the support surface SF by the downward biasing force having a magnitude corresponding to the difference between the biasing forces F1 and F3. Therefore, even when the truck frame 20B vibrates up and down, the motor bracket 42A is suppressed from being separated from the support surface SF.
As shown in Fig. 9, it is assumed that the truck frame 20B is displaced downward with respect to the axle 30 and the interval CL is formed between the motor bracket 42A, which abuts against the guide unit 60, and the support surface SF of the truck frame 20B.
In the third embodiment, the second biasing member 80 still biases the motor bracket 42A in the upward direction even in a state where the motor bracket 42A is separated from the support surface SF of the truck frame 20B and is supported on the guide unit 60. In other words, the pre-compression amount by which the second biasing member 80 is compressed in advance in the reference state (see Fig. 8) is larger than the prescribed amount PA for the motor bracket 42A and the guide unit 60 to abut against each other. A biasing force F4 of the second biasing member 80 acts as a support force with which the truck frame 20B supports the motor bracket 42A.
For this reason, the second biasing member 80 reduces the load acting on the guide unit 60 from the motor bracket 42A by the amount of the biasing force F4. As described above, the weight acting on the guide unit 60 is included in the "unsprung weight" below the axle spring 33. On the other hand, the biasing force F4 of the second biasing member 80 is supported by the non-rotary unit 32 of the axle 30 via the truck frame 20B and the axle spring 33. Therefore, the biasing force F4 is not included in the "unsprung weight". Therefore, in the third embodiment, even when the weight of the motor bracket 42A (drive unit 40) is supported by the guide unit 60, the unsprung weight is reduced by the amount of the biasing force F4.

[Operations and Effects of Embodiment]

A truck according to a first aspect includes a truck frame 20, an axle 30 including a non-rotary unit 32 that supports the truck frame 20 via an axle spring 33, a drive unit 40 including a hollow-shaped motor 41 through which the axle 30 is inserted, and a motor bracket 42 that holds the motor 41 and is supported by the truck frame 20 in a state of being relatively movable in an upward direction, a joint unit 50 that connects the motor 41 and the axle 30 to be capable of transmitting power, and a guide unit 60 that is provided on the non-rotary unit 32 and that abuts against the drive unit 40 to restrict displacement of the drive unit 40 with respect to the axle 30 when the truck frame 20 is displaced by a prescribed amount PA or more with respect to the axle 30.
In the truck according to the first aspect, the drive unit 40 is supported by the truck frame 20 in a state of being relatively movable in the upward direction. In this manner, the weight of the drive unit 40 acts on the truck frame 20 above the axle spring 33. Therefore, the unsprung weight can be reduced as compared with a case where the drive unit 40 is directly supported by the axle 30. In a case where truck frame 20 is displaced by the prescribed amount PA or more, the guide unit 60 abuts against the drive unit 40 to restrict the displacement of the drive unit 40 (that is, the motor 41). Therefore, the displacement of the motor 41 can be suppressed within the range of the prescribed amount PA. Accordingly, it is possible to reduce a displacement allowance required for the joint unit 50 while suppressing an increase in an unsprung weight in the truck 10 having a structure in which the motor 41 is directly connected to the axle 30 via the joint unit 50. As a result, since the required design specification for the joint unit 50 is relaxed, the degree of freedom in designing the joint unit 50 can be increased. In addition, since the relative displacement amount to be absorbed by the joint unit 50 is limited, the stress amplitude acting on the joint unit 50 is reduced, and as a result, the life of the joint unit 50 can be extended.
The truck according to a second aspect further includes a first biasing member 70 that biases the drive unit 40 toward the guide unit 60 in a state where the drive unit 40 and the guide unit 60 abut against each other. In this manner, the drive unit 40 is pressed against the guide unit 60 by the first biasing member 70 in a state where the truck frame 20A is displaced by the prescribed amount PA or more and the guide unit 60 abuts against the drive unit 40. Therefore, the drive unit 40 is suppressed from being separated from the guide unit 60 by the biasing force even in a case where the guide unit 60 vibrates up and down due to the vibration transmitted from the wheels 31 during the traveling of the truck 10A. Therefore, it is possible to suppress the vibration of the motor 41 with respect to the axle 30.
The truck according to a third aspect further includes a second biasing member 80 that is provided between the truck frame 20B and the motor bracket 42 and biases the motor bracket 42 in the upward direction away from a support surface SF of the truck frame 20B. Accordingly, in a state where the truck frame 20B is displaced by the prescribed amount PA or more and the guide unit 60 abuts against the drive unit 40, the weight of the drive unit 40 can be shared by the truck frame 20B side (above the axle spring 33) by the amount of the biasing force F4 of the second biasing member 80. Therefore, the unsprung weight can be reduced.
In the truck according to a fourth aspect, the prescribed amount PA is smaller than a displacement allowance of the joint unit 50 in an upward-downward direction. In this manner, the relative displacement of the motor 41 with respect to the axle 30 can be within a range that the joint unit 50 can allow. In other words, the relative displacement of the motor 41 with respect to the axle 30 is limited to within the prescribed amount PA, so that the displacement amount that the joint unit 50 has to allow can be reduced. Therefore, the required design specification for the joint unit 50 can be relaxed, and the life of the joint unit 50 can be extended.
In the truck according to a fifth aspect, the guide unit 60 is provided at a position at which the guide unit 60 is not in contact with the drive unit 40 when the displacement of the truck frame 20 with respect to the axle 30 is less than the prescribed amount PA. In this manner, in a case where the displacement of the truck frame 20 is less than the prescribed amount PA, the weight of the drive unit 40 is not directly applied to the axle 30 via the guide unit 60, and thus the unsprung weight can be effectively reduced.
In the present specification, the motor bracket 42 is described as being relatively displaced in parallel as shown in Fig. 2 and the like. However, even in a case where only one side of the motor bracket 42 is relatively displaced (that is, in a case where the truck frame 20 is inclined with respect to the axle 30), the displacement amount on the one side can be limited by the guide unit 60. Therefore, the same effect as described above can be obtained.

[Modification Example]

In the above-described embodiment, an example has been shown in which the guide unit 60 abuts against the lower surface of the motor bracket 42 (support plate portion 43) of the drive unit 40 to restrict the displacement of the drive unit 40. However, the guide unit 60 may abut against any portion of the drive unit 40. Fig. 10 is a schematic view showing a truck 10C according to a first modification example. In the example of Fig. 10, the guide unit 60 abuts against an abutment piece 46 provided in the connection portion 44 of the motor bracket 42 to restrict the displacement of the drive unit 40 with respect to the axle 30. In this example, the guide unit 60 is configured by an L-shaped bracket that extends upward from the non-rotary unit 32 of the axle 30 and then is bent inward in the width direction at an upper end portion. The abutment piece 46 protrudes outward in the width direction from the side surface of the connection portion 44 on the outer side in the width direction to the upper position of the guide unit 60. Accordingly, when the drive unit 40 is downwardly displaced as the truck frame 20 is downwardly displaced, the guide unit 60 abuts against the abutment piece 46 to restrict the displacement of the drive unit 40 and to support the drive unit 40. In addition, for example, the guide unit 60 may abut against a part of the housing of the motor 41 or an abutment piece provided in the housing.
In addition, the guide unit 60 may not be provided separately from the non-rotary unit 32 of the axle 30. That is, the guide unit 60 may be a protrusion or the like integrally formed on the non-rotary unit 32 (bearing housing).
In addition, in the above-described embodiment, an example in which the motor bracket 42 (the support plate portion 43) is placed on the upper surface of the truck frame 20 (an example in which the upper surface of the truck frame 20 is the support surface SF) has been shown. However, the motor bracket 42 may be placed on a portion other than the upper surface of the truck frame 20. In the example of Fig. 10, the motor bracket 42 is supported by an L-shaped support bracket 27 provided on the inner side surface of the side beam 21 of the truck frame 20. The upper surface of the distal end portion of the support bracket 27 is the support surface SF. In addition, the motor bracket 42 may be supported at a position below the truck frame 20 (side beam 21) by a bracket or the like.
In addition, in the above-described embodiment, an example has been shown in which the non-rotary unit 32, the axle spring 33, and the guide unit 60 are disposed inside a pair of wheels 31 of the axle 30 in the width direction. However, each of these units may be disposed outside the pair of wheels 31. Fig. 11 is a schematic view showing a truck 10D according to a second modification example in which the non-rotary unit 32, the axle spring 33, and the guide unit 60 are disposed outside the pair of wheels 31.
In addition, in the above-described embodiment, an example in which the joint unit 50 is a flexible joint having the elastically deformable coupling 52 has been shown. However, a structure of the joint unit 50 is not particularly limited, and the joint unit 50 may be a joint other than the flexible joint.

Reference Signs List

10, 10A, 10B, 10C, 10D: truck
20, 20A, 20B: truck frame
30: axle
32: non-rotary unit
40: drive unit
41: motor
42, 42A: motor bracket
50: joint unit
60: guide unit
70: first biasing member
80: second biasing member
PA: prescribed amount
SF: support surface

Claims

A truck comprising:
a truck frame;

an axle including a non-rotary unit that supports the truck frame via an axle spring;

a drive unit including a hollow-shaped motor through which the axle is inserted, and a motor bracket that holds the motor and is supported by the truck frame in a state of being relatively movable in an upward direction;

a joint unit that connects the motor and the axle to be capable of transmitting power; and

a guide unit that is provided on the non-rotary unit and that abuts against the drive unit to restrict displacement of the drive unit with respect to the axle when the truck frame is displaced by a prescribed amount or more with respect to the axle.
The truck according to Claim 1, further comprising:
a first biasing member that biases the drive unit toward the guide unit in a state where the drive unit and the guide unit abut against each other.
The truck according to Claim 2, further comprising:
a second biasing member that is provided between the truck frame and the motor bracket and biases the motor bracket in the upward direction away from a support surface of the truck frame.
The truck according to any one of Claims 1 to 3,
wherein the prescribed amount is smaller than a displacement allowance of the joint unit in an upward-downward direction.
The truck according to any one of Claims 1 to 3,
wherein the guide unit is provided at a position at which the guide unit is not in contact with the drive unit when the displacement of the truck frame with respect to the axle is less than the prescribed amount.