Drive unit

Abstract

To prevent movement during stopping.SOLUTION: The drive unit includes a frame, a drive wheel, an electric motor, a rotary member, and a brake mechanism. The drive wheel is rotatably supported by the frame. The electric motor is supported by the frame. The electric motor is configured to drive the drive wheel. The rotation member is configured to rotate in conjunction with the drive wheel. The brake mechanism includes an engagement portion. The brake mechanism is switchable between a braking state and a released state. When the brake mechanism is in the braking state, the engagement portion engages with the rotary member to brake the rotation of the rotary member. When the brake mechanism is in the released state, the engagement of the engaging portion with the rotating member is released to allow the rotating member to rotate.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a drive unit. [Background technology]

[0002] It has been proposed to improve the performance of a moving body by attaching a drive unit to a moving body that moves at low speed, such as a pallet truck, a hand lift truck, a hand truck, or a wheelchair (Patent Document 1). The drive unit includes a drive wheel and an electric motor. The electric motor outputs an assist force to assist the human power when the moving body is driven by human power. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2014-512307 Summary of the Invention [Problem to be solved by the invention]

[0004] A moving body equipped with the above-described drive unit may move while stopped. Therefore, an object of the present invention is to provide a drive unit that can prevent the moving body from moving while stopped. [Means for solving the problem]

[0005] A drive unit according to a first aspect includes a frame, a drive wheel, an electric motor, a rotating member, and a brake mechanism. The drive wheel is rotatably supported by the frame. The electric motor is supported by the frame. The electric motor is configured to drive the drive wheel. The rotating member is configured to rotate in conjunction with the drive wheel. The brake mechanism has an engagement portion. The brake mechanism is switchable between a braking state and a release state. When the brake mechanism is in the braking state, the engagement portion engages with the rotating member to brake rotation of the rotating member. When the brake mechanism is in the release state, the engagement portion is released from engagement with the rotating member, allowing the rotating member to rotate.

[0006] According to this configuration, the engaging portion of the brake mechanism can engage with the rotating member to brake the rotation of the rotating member, thereby preventing the rotating member from moving while the vehicle is stopped.

[0007] The drive unit according to the second aspect is the drive unit according to the first aspect, and is configured as follows: The engagement portion is movable along the axial direction of the rotating member.

[0008] A drive unit according to a third aspect is the drive unit according to the first or second aspect, and is configured as follows: the rotating member is a sprocket, and the engaging portion engages with the teeth of the sprocket when the brake mechanism is in a braking state.

[0009] A drive unit according to a fourth aspect is the drive unit according to the third aspect, and is configured as follows: A part of the engaging portion is disposed radially outward of the tip of the sprocket tooth.

[0010] A drive unit according to a fifth aspect is the drive unit according to the third or fourth aspect, and is configured as follows: The engaging portion abuts against the sprocket teeth radially outward from the pitch circle of the sprocket.

[0011] A sixth aspect of the present invention relates to the drive unit of any one of the first to fifth aspects, and further includes a transmission member. The transmission member is configured to transmit power between the electric motor and the drive wheels. The rotating member is attached to an output shaft of the electric motor. The electric motor and the engaging portion are movable in the direction in which the transmission member extends.

[0012] A drive unit according to a seventh aspect is the drive unit according to any one of the first to sixth aspects and is configured as follows: The brake mechanism has a mounting plate and a brake main body. The mounting plate is attached to the frame. The brake main body is attached to the mounting plate. The brake main body has an engagement portion at its tip.

[0013] A drive unit according to an eighth aspect is the drive unit according to the seventh aspect, and is configured as follows: the electric motor is attached to the frame so as to be swingable about a swing shaft, and the mounting plate is attached to the frame so as to be swingable about the swing shaft.

[0014] A drive unit according to a ninth aspect is the drive unit according to any one of the first to eighth aspects, further comprising a drive wheel sprocket. The drive wheel sprocket is attached to the rotating shaft of the drive wheel. The rotating member is an electric motor sprocket attached to the output shaft of the electric motor.

[0015] A drive unit according to a tenth aspect is the drive unit according to the ninth aspect, and is configured as follows: The engagement portion engages with the teeth of the electric motor sprocket on an imaginary line connecting the rotational shaft of the electric motor sprocket and the rotational shaft of the drive wheel sprocket, or above the imaginary line. [Effects of the Invention]

[0016] According to the present invention, it is possible to prevent the vehicle from moving while stopped. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a side view of a drive unit mounted on a pallet truck. [Figure 2] FIG. [Figure 3] FIG. 10 is a side view of the drive unit with one side plate and the like removed. [Figure 4] Cross-sectional view of line IV-IV in Figure 2. [Figure 5] 5 is a view corresponding to FIG. 4 when the brake mechanism is in a released state. [Figure 6] 10 is a diagram showing an engagement state between an electric motor sprocket and an engagement portion. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of a drive unit 100 attached to a pallet truck 200 will be described below with reference to the drawings. The drive unit 100 is configured to assist the travel of a mobile object. The drive unit 100 is attached to the mobile object. The mobile object is driven by human power. The mobile object travels at a low speed. The mobile object is configured to transport an object. The concept of an object includes people, etc. Examples of such mobile objects include a pallet truck, a hand lift truck, a hand truck, and a wheelchair. In this embodiment, the mobile object is a pallet truck 200. In the following description, "forward" means the direction in which a user moves while towing the pallet truck 200, and "rearward" means the direction in which a user moves while pushing the pallet truck 200.

[0019] <Pallet truck> FIG. 1 is a side view of a pallet truck 200 to which a drive unit 100 is attached. The right side of FIG. 1 is the front, and the left side of FIG. 1 is the rear. As shown in FIG. 1, the pallet truck 200 has a loading platform (a pair of fork arms) 201, an operating handle 202, and a plurality of wheels 204. Each wheel 204 is a non-drive wheel. The drive unit 100 is attached to this pallet truck 200.

[0020] <Drive unit> Fig. 2 is a side view of the drive unit 100, and Fig. 3 is a side view of the drive unit 100 with one side plate 21 and the like removed. As shown in Figs. 2 and 3, the drive unit 100 has a frame 2, drive wheels 3, drive wheel sprockets 4, an electric motor 5, an electric motor sprocket 6 (an example of a rotating member), a chain 7 (an example of a transmission member), and a brake mechanism 8. The drive unit 100 also has a battery 11, a mount plate 12, and a pair of wheel covers 13.

[0021] <frame> The frame 2 is configured to support each member. The frame 2 has a pair of side plates 21. The side plates 21 are arranged at a distance from each other in the width direction. The side plates 21 are fastened to each other by a plurality of bolts or the like.

[0022] <Drive wheels and drive sprockets> The drive wheels 3 are rotatably supported by the frame 2. More specifically, the rotating shafts 31 of the drive wheels 3 are rotatably supported by the frame 2 via bearing members or the like. The rotating shafts 31 of the drive wheels 3 extend in the width direction. The rotating shafts 31 rotate integrally with the drive wheels 3.

[0023] The lower ends of the drive wheels 3 are positioned lower than the lower ends of the frame 2. In other words, the drive wheels 3 are in contact with the floor surface. It is preferable that the frame 2 is not in contact with the floor surface. The drive wheels 3 roll on the floor surface. In this embodiment, the drive unit 100 has one drive wheel 3, but the drive unit 100 may have multiple drive wheels 3.

[0024] The drive wheel sprocket 4 is attached to the rotation shaft 31 of the drive wheel 3. The drive wheel sprocket 4 is configured to rotate integrally with the drive wheel 3.

[0025] <Electric motors, sprockets for electric motors, chains> The electric motor 5 outputs an assist force for assisting the travel of the pallet truck 200 when the user is manually traveling the pallet truck 200. Note that the electric motor 5 may output torque for traveling the pallet truck 200 while the user is operating the operation part of the operating handle 202. The electric motor 5 is configured to drive the drive wheels 3 to rotate.

[0026] The electric motor 5 has an output shaft 51. The output shaft 51 rotates integrally with the rotor of the electric motor 5. The output shaft 51 extends in the width direction. The direction in which the output shaft 51 extends is also referred to as the axial direction. In other words, the width direction is synonymous with the axial direction.

[0027] The electric motor sprocket 6 is attached to the output shaft 51 of the electric motor 5. The electric motor sprocket 6 is configured to rotate integrally with the output shaft 51. The electric motor sprocket 6 is disposed forward of the drive wheel sprocket 4. The electric motor sprocket 6 is also disposed above the drive wheel sprocket 4.

[0028] The chain 7 is configured to transmit power between the electric motor sprocket 6 and the drive wheel sprocket 4. In other words, the chain 7 is stretched over the electric motor sprocket 6 and the drive wheel sprocket 4.

[0029] The electric motor sprocket 6 rotates integrally with the drive wheel sprocket 4 via the chain 7, and the drive wheel sprocket 4 rotates integrally with the drive wheel 3. In other words, the electric motor sprocket 6 is configured to rotate in conjunction with the drive wheel 3.

[0030] The electric motor 5 is supported by the frame 2. The electric motor 5 is disposed forward relative to the drive wheels 3. The electric motor 5 is movable in the direction in which the chain 7 extends. In other words, the electric motor 5 is movable in the direction in which the electric motor sprocket 6 moves away from or towards the drive wheel sprocket 4.

[0031] Specifically, the electric motor 5 is attached to the frame 2 so as to be able to swing about a swing axis O. More specifically, the electric motor 5 is attached to a plurality of bolts 101 that extend in the width direction so as to fasten the pair of side plates 21 together. One of the plurality of bolts 101 forms the swing axis O. The remaining bolts 101 fasten the pair of side plates 21 together via elongated holes formed in each of the pair of side plates 21. This allows the electric motor 5 to swing about the swing axis O.

[0032] In Figure 3, when the electric motor 5 rotates clockwise around the swing axis O, the electric motor sprocket 6 moves in a direction away from the drive wheel sprocket 4. As a result, if the chain 7 is loose, it can be tightened. Note that Figures 2 and 3 show the state after the electric motor 5 has rotated clockwise.

[0033] <Brake mechanism> The brake mechanism 8 is configured to brake the rotation of the drive wheels 3 of the drive unit 100. The brake mechanism 8 is switchable between a braking state and a release state. In the braking state, the brake mechanism 8 brakes the rotation of the electric motor sprocket 6. Note that the electric motor sprocket 6 rotates in conjunction with the drive wheels 3, so braking the rotation of the electric motor sprocket 6 also brakes the rotation of the drive wheels 3.

[0034] On the other hand, in the released state, the brake mechanism 8 allows the rotation of the electric motor sprocket 6. In other words, in the released state, the brake mechanism 8 releases the braking of the rotation of the electric motor sprocket 6.

[0035] The brake mechanism 8 has a mounting plate 81 and a brake main body 82. The mounting plate 81 is attached to the frame 2. More specifically, the mounting plate 81 is fastened to the side plate 21 by a plurality of bolts 101 to which the electric motor 5 is attached. Therefore, the mounting plate 81 is attached to the frame 2 so as to be able to swing about the swing axis O. The mounting plate 81 is disposed so as to cover an opening 211 formed in one of the side plates 21.

[0036] The brake main body 82 is attached to the mounting plate 81. Therefore, the brake main body 82 can swing together with the mounting plate 81 around the swing axis O. That is, the brake main body 82 can move in the direction in which the chain 7 extends, similar to the electric motor 5. More specifically, the brake main body 82 swings integrally with the electric motor 5. The brake main body 82 extends through the side plate 21 via the opening 211.

[0037] Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 2. In Fig. 4, the brake mechanism 8 is in a braking state. As shown in Fig. 4, the brake main body 82 has an engagement pin 821 (an example of an engagement portion) at its tip. The engagement pin 821 advances or retreats in the axial direction by operating an operation portion 822 of the brake main body 82. In other words, the engagement pin 821 is movable along the axial direction of the electric motor sprocket 6.

[0038] The engagement pin 821 advances or retracts in the axial direction by rotating the operating portion 822. For example, the brake main body 82 is an index plunger. The engagement pin 821 engages with the teeth of the electric motor sprocket 6 by advancing in the axial direction. On the other hand, the engagement pin 821 disengages from the teeth of the electric motor sprocket 6 by retracting in the axial direction. Note that FIG. 4 shows the state in which the engagement pin 821 advances. When the engagement pin 821 retracts, the engagement pin 821 moves to the right in FIG. 4 and is disengaged.

[0039] When the brake mechanism 8 is in a braking state, the engagement pin 821 engages with the teeth of the electric motor sprocket 6. More specifically, when the brake mechanism 8 is in a braking state, the engagement pin 821 advances toward the electric motor sprocket 6 and engages with the teeth of the electric motor sprocket 6. On the other hand, when the brake mechanism 8 is in a released state, the engagement pin 821 is released from engagement with the teeth of the electric motor sprocket 6. More specifically, when the brake mechanism 8 is in a released state, the engagement pin 821 retracts away from the electric motor sprocket 6 and is released from engagement with the teeth of the electric motor sprocket 6.

[0040] Fig. 6 is a diagram showing an engagement state between the engagement pin 821 and the electric motor sprocket 6. As shown in Fig. 6, when the brake mechanism 8 is in a braking state, the engagement pin 821 is engaged with the teeth of the electric motor sprocket 6. In other words, the engagement pin 821 is disposed between a pair of adjacent teeth.

[0041] A portion of the engagement pin 821 is disposed radially outward from the tooth tips of the electric motor sprocket 6. That is, a portion of the engagement pin 821 protrudes outward from the space between a pair of adjacent teeth. More specifically, more than half of the engagement pin 821 protrudes outward from the space between a pair of adjacent teeth. The engagement pin 821 abuts against a tooth of the electric motor sprocket 6 radially outward from the pitch circle P of the electric motor sprocket 6.

[0042] 3, the engagement pin 821 engages with the teeth of the electric motor sprocket 6 on an imaginary line L. Here, the imaginary line L is a line connecting the rotational axis of the electric motor sprocket 6 and the rotational axis of the drive wheel sprocket 4.

[0043] In the drive unit 100 configured as described above, by putting the brake mechanism 8 into a braking state when the pallet truck 200 is stopped, that is, by operating the operating part 822 of the brake main body 82 to engage the engagement pin 821 with the electric motor sprocket 6, the drive wheels 3 can be made non-rotatable. As a result, the pallet truck 200 can be maintained in a stopped state.

[0044] <Battery and mounting plate> 2 and 3, the battery 11 is attached to the frame 2 via a mount plate 12. The battery 11 supplies power to the electric motor 5 and other components. The mount plate 12 protrudes widthwise and forward beyond the battery 11 to prevent the battery 11 from colliding with obstacles and the like. The outer periphery of the mount plate 12 is made of an elastic body with a core metal inside.

[0045] <Wheel cover> Each wheel cover 13 is provided to prevent feet or the like from coming into contact with the wheels 204 of the pallet truck 200. Each wheel cover 13 is disposed in front of the corresponding wheel 204. Each wheel cover 13 is attached to the frame 2.

[0046] More specifically, each wheel cover 13 is fastened to the frame 2 by a bolt 102. Each wheel cover 13 also has a notch 131. Each wheel cover 13 is hooked onto a protruding portion 103 that protrudes from the frame 2 via this notch 131. This prevents each wheel cover 13 from rotating. Note that this protruding portion 103 and the notch 131 overlap with the wheel 204 in a side view.

[0047] [Variations] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications are possible without departing from the spirit of the present invention. Note that the following modifications can basically be applied simultaneously.

[0048] (a) The rotating member to be braked by the brake mechanism 8 does not have to be the electric motor sprocket 6. For example, the brake mechanism 8 may brake the drive wheel sprocket 4. Alternatively, another sprocket may be installed between the electric motor sprocket 6 and the drive wheel sprocket 4, and the brake mechanism 8 may brake that other sprocket. Furthermore, the rotating member to be braked by the brake mechanism 8 does not have to be the sprocket 6.

[0049] (b) In the above embodiment, the engaging portion of the brake mechanism is configured by the engaging pin 821 that moves forward and backward, but the engaging portion of the brake mechanism is not limited to this. For example, the engaging portion of the brake mechanism may be a plate shaped to fit the teeth of the electric motor sprocket 6. In this case, the plate is configured to move forward and backward so as to move toward and away from the electric motor sprocket 6, thereby engaging with and disengaging from the teeth of the electric motor sprocket 6.

[0050] (c) A reducer may be installed between the electric motor 5 and the drive wheels 3. In this case, the reducer is disposed between the electric motor sprocket 6 and the drive wheel sprocket 4. The reducer reduces the speed of the power from the electric motor 5 and transmits it to the drive wheels.

[0051] (d) The engagement pin 821 may be engaged with the teeth of the sprocket 6 for the electric motor above the imaginary line L. [Explanation of symbols]

[0052] 2: Frame 3: Drive wheels 31: Rotating shaft 4: Drive wheel sprocket 5: Electric motor 51: Output shaft 6: Electric motor sprocket 7: Chain 8: Brake mechanism 81: Mounting plate 82: Brake body 821: Engagement pin 100: Drive unit

Claims

1. The frame and a drive wheel rotatably supported by the frame; an electric motor supported by the frame and configured to drive the drive wheels; a rotating member configured to rotate in conjunction with the drive wheel; a brake mechanism having an engaging portion, the brake mechanism being switchable between a braking state in which the engaging portion engages with the rotating member to brake the rotation of the rotating member, and a release state in which the engagement portion is released from the rotating member to allow the rotating member to rotate; A drive unit comprising:

2. The engaging portion is movable along the axial direction of the rotating member.

2. The drive unit according to claim 1.

3. the rotating member is a sprocket, The engaging portion engages with the teeth of the sprocket when the brake mechanism is in the braking state.

2. The drive unit according to claim 1.

4. a part of the engaging portion is disposed radially outward of the tip of a tooth of the sprocket; 4. The drive unit according to claim 3.

5. The engaging portion abuts against a tooth of the sprocket radially outward from a pitch circle of the sprocket.

4. The drive unit according to claim 3.

6. a transmission member configured to transmit power between the electric motor and the drive wheels; the rotating member is attached to an output shaft of the electric motor; the electric motor and the engaging portion are movable in a direction in which the transmission member extends; 2. The drive unit according to claim 1.

7. the brake mechanism includes a mounting plate attached to the frame and a brake main body attached to the mounting plate, The brake main body has the engagement portion at a tip end thereof.

2. The drive unit according to claim 1.

8. the electric motor is attached to the frame so as to be swingable about a swing axis; The mounting plate is attached to the frame so as to be swingable about the swing axis.

8. A drive unit according to claim 7.

9. a drive wheel sprocket attached to a rotation shaft of the drive wheel; the rotating member is an electric motor sprocket attached to the output shaft of the electric motor; 2. The drive unit according to claim 1.

10. the engaging portion engages with the teeth of the electric motor sprocket on an imaginary line connecting the rotational axis of the electric motor sprocket and the rotational axis of the drive wheel sprocket, or above the imaginary line; 10. A drive unit according to claim 9.

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