Drive unit

Abstract

To provide a drive unit capable of varying a wheel pressure, which is applied to a drive wheel, according to a weight of a moving body.SOLUTION: A link mechanism includes a first link, second link, and first joint. The first link is swingably attached to an upper unit. The first link extends downward from the upper unit in a second direction opposite to a first direction. The second link is swingably attached to a lower unit. The second link extends upward from the lower unit in the second direction. The first joint joins the first link and second link with each other. When a human power is inputted in the first direction, an operation member moves the first joint in the first direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] There has been proposed a drive unit that is attached to a moving body that does not have a drive source, such as a cart. For example, the drive unit disclosed in Patent Document 1 has an electric motor and a drive wheel driven by the electric motor. The drive unit also has a pressure-receiving spring member for applying wheel pressure to the drive wheel. The pressure-receiving spring member biases the drive wheel toward the ground to apply wheel pressure to the drive wheel, thereby preventing the drive wheel from spinning. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7040738 Summary of the Invention [Problem to be solved by the invention]

[0004] In the drive unit configured as described above, if the weight of the moving body is light compared to the setting of the spring member, the wheels of the moving body may float. Also, if the spring member is set to match a light moving body, if the moving body is heavy, the wheel pressure applied to the drive wheels by the spring member may be insufficient, and the drive wheels may spin freely.

[0005] An object of the present invention is to provide a drive unit capable of changing the wheel pressure applied to the drive wheels in accordance with the weight of a moving body. [Means for solving the problem]

[0006] The drive unit according to the first aspect is configured to be attached to a moving body capable of traveling in a first direction. The drive unit includes an upper unit, a lower unit, a drive source, a link mechanism, and an operating member. The upper unit is configured to be attached to the moving body. The lower unit has drive wheels. The lower unit is arranged to be movable in the up and down direction relative to the upper unit. The drive source is configured to drive the drive wheels. The link mechanism has a first link, a second link, and a first joint. The first link is swingably attached to the upper unit. The first link extends downward from the upper unit in a second direction opposite to the first direction. The second link is swingably attached to the lower unit. The second link extends upward from the lower unit in the second direction. The first joint connects the first link and the second link. The operating member is configured to move the first joint in the first direction when human force is input in the first direction.

[0007] According to this configuration, when a user inputs a human force in the first direction to the operating member to make the moving body travel in the first direction, the first joint moves in the first direction, and the upper end of the first link and the lower end of the second link move in a direction away from each other. That is, a force acts on the upper unit and the lower unit in a direction away from each other. As a result, wheel pressure is applied to the drive wheels. Here, if the weight of the moving body is large, the human force input by the user to the operating member becomes large, and the wheel pressure applied to the drive wheels also becomes large. Also, if the weight of the moving body is small, the human force input by the user to the operating member becomes small, and the wheel pressure applied to the drive wheels also becomes small. In this way, the wheel pressure applied to the drive wheels can be changed according to the weight of the moving body.

[0008] The drive unit according to the second aspect is configured as follows in the drive unit according to the first aspect. The link mechanism has a third link, a fourth link, and a second joint. The third link is swingably attached to the upper unit. The third link extends downward from the upper unit in a first direction. The fourth link is swingably attached to the lower unit. The fourth link extends upward from the lower unit in the first direction. The second joint connects the third link and the fourth link. The operating member is configured to move the second joint in the second direction when human force is input in the second direction.

[0009] According to this configuration, when a user inputs a human force in the second direction to the operating member in order to make the moving body travel in the second direction, the second joint moves in the second direction, and the upper end of the third link and the lower end of the fourth link move in a direction away from each other. That is, a force acts on the upper unit and the lower unit in a direction away from each other. As a result, wheel pressure is applied to the drive wheels. Here, if the weight of the moving body is large, the human force input by the user to the operating member becomes large, and the wheel pressure applied to the drive wheels also becomes large. Also, if the weight of the moving body is small, the human force input by the user to the operating member becomes small, and the wheel pressure applied to the drive wheels also becomes small. In this way, even when the moving body is traveled in the second direction, the wheel pressure applied to the drive wheels can be changed according to the weight of the moving body.

[0010] The drive unit according to a third aspect is the drive unit according to the first or second aspect, further comprising a biasing member. The biasing member biases the upper unit and the lower unit in directions away from each other.

[0011] A drive unit according to a fourth aspect is the drive unit according to any one of the first to third aspects, and is configured as follows: the operating member has a first contact surface facing a first direction. The first contact surface faces the first joint or a member that moves in the first direction integrally with the first joint.

[0012] The drive unit according to a fifth aspect is the drive unit according to the second aspect, and is configured as follows: the operating member has a second contact surface facing the second direction. The second contact surface faces the second joint or a member that moves integrally with the second joint in the second direction. Effect of the Invention

[0013] According to the present invention, the wheel pressure applied to the drive wheels can be changed in accordance with the weight of the moving body. [Brief description of the drawings]

[0014] [Figure 1] FIG. [Diagram 2] FIG. 4 is a schematic diagram showing a state of the drive unit when traveling in a first direction. [Diagram 3] FIG. 6 is a schematic diagram showing a state of the drive unit when traveling in a second direction. [Figure 4] FIG. 11 is a schematic diagram of a drive unit according to a modified example. [Diagram 5] FIG. 11 is a schematic diagram of a drive unit according to another modified example. [Figure 6] FIG. 11 is a schematic diagram of a drive unit according to still another modified example. [Figure 7] FIG. 11 is a schematic diagram of a drive unit according to still another modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the drive unit 100 according to this embodiment will be described with reference to the drawings. FIG. 1 is a side view showing the drive unit 100 attached to a dolly 200 (an example of a moving body). In this embodiment, the first direction is the direction in which the drive unit 100 moves when it is pulled, and the second direction is the direction in which the drive unit 100 moves when it is pushed. When using the drive unit 100, the user is positioned in the first direction relative to the drive unit 100. The right direction in FIG. 1 is the first direction, and the left direction in FIG. 1 is the second direction. The axial direction is the direction in which the rotation axis of the drive wheel 32 extends.

[0016] As shown in FIG. 1, the drive unit 100 is attached to a dolly 200. The dolly 200 has a platform 201 and a number of wheels (not shown). The dolly 200 is a moving body that does not have a driving source such as an electric motor. The wheels of the dolly 200 are driven wheels. The dolly 200 can travel in a first direction when pulled by a user. In addition, the dolly 200 can travel in a second direction when pushed by a user. Note that the drive unit 100 can be attached to moving bodies other than dollies, such as stretchers, basket carts, and wheelchairs.

[0017] The drive unit 100 is configured to be attached to a cart 200. The drive unit 100 includes an upper unit 2, a lower unit 3, an electric motor 4 (an example of a drive source), a link mechanism 5, and an operating member 6.

[0018] The upper unit 2 is configured to be attached to the dolly 200. For example, the upper unit 2 has a toggle clamp, and may be attached to the dolly 200 using the toggle clamp. Alternatively, the upper unit 2 may be attached to the dolly 200 by a bolt or the like. The upper unit 2 is fixed to the dolly 200 so as to move integrally therewith. Note that, although the upper unit 2 is disposed below the dolly 200, it does not have to be disposed below the dolly 200.

[0019] The lower unit 3 has a frame 31 and a pair of drive wheels 32. The drive wheels 32 are rotatably supported by the frame 31. The lower unit 3 is arranged so as to be movable in the up and down direction relative to the upper unit 2. In other words, the distance between the lower unit 3 and the upper unit 2 is variable. For example, an elastic member may be arranged between the upper unit 2 and the lower unit 3.

[0020] The electric motor 4 is supported by the lower unit 3. In detail, the electric motor 4 is supported by a frame 31 of the lower unit 3. The electric motor 4 is configured to drive driving wheels 32. The electric motor 4 is supplied with power from a battery (not shown).

[0021] The link mechanism 5 has a first link 51, a second link 52, a third link 53, a fourth link 54, a first joint 55, and a second joint 56. The link mechanism 5 also has a third joint 57 and a fourth joint 58.

[0022] The first link 51 is attached to the upper unit 2 so as to be able to swing. In detail, the first link 51 is attached at its upper end to the upper unit 2. The upper end of the first link 51 is configured to move integrally with the upper unit 2 in the up and down direction.

[0023] The first link 51 extends downward in the second direction from the upper unit 2. That is, the lower end of the first link 51 is disposed in the second direction relative to the upper end of the first link 51.

[0024] The first link 51 can swing about the first swing axis O1. In detail, the first link 51 swings in a first direction and a second direction about the first swing axis O1. When the first link 51 swings in the first direction, the lower end of the first link 51 moves in the first direction. That is, in FIG. 1, the first link 51 swings counterclockwise about the first swing axis O1. When the first link 51 swings in the second direction, the lower end of the first link 51 moves in the second direction. That is, in FIG. 1, the first link 51 swings clockwise about the first swing axis O1.

[0025] The second link 52 is attached to the lower unit 3 so as to be able to swing. More specifically, the second link 52 is attached to the lower unit 3 at its lower end. The second link 52 is attached to a member of the lower unit 3 that moves up and down integrally with the drive wheel 32. The lower end of the second link 52 is configured to move in the up and down direction integrally with the lower unit 3. In this embodiment, the second link 52 is attached to a shaft that supports the drive wheel 32.

[0026] The second link 52 extends upward in the second direction from the lower unit 3. That is, the upper end of the second link 52 is disposed in the second direction relative to the lower end of the second link 52.

[0027] The second link 52 can swing about the second swing axis O2. In particular, the second link 52 swings in a first direction and a second direction about the second swing axis O2. When the second link 52 swings in the first direction, the upper end of the second link 52 moves in the first direction. That is, in FIG. 1, the second link 52 swings clockwise about the second swing axis O2. When the second link 52 swings in the second direction, the upper end of the second link 52 moves in the second direction. That is, in FIG. 1, the second link 52 swings counterclockwise about the second swing axis O2.

[0028] The first joint 55 connects the first link 51 and the second link 52. More specifically, the first joint 55 connects a lower end of the first link 51 and an upper end of the second link 52. The first link 51 and the second link 52 are connected by the first joint 55 to be rotatable with each other.

[0029] The first joint 55 is disposed in the second direction with respect to a virtual line L connecting the first oscillation axis O1 and the second oscillation axis O2. The first joint 55 is disposed so as to be movable in the first and second directions. When the first joint 55 moves in the first direction, that is, when the first joint 55 approaches the virtual line L, the first oscillation axis O1 and the second oscillation axis O2 move in directions away from each other. Note that the first joint 55 does not move beyond the virtual line L in the first direction.

[0030] The third link 53 is attached to the upper unit 2 so as to be able to swing. More specifically, the third link 53 is attached at its upper end to the upper unit 2. The upper end of the third link 53 is configured to move vertically together with the upper unit 2.

[0031] The third link 53 extends downward in the first direction from the upper unit 2. That is, the lower end of the third link 53 is disposed in the first direction relative to the upper end of the third link 53.

[0032] The third link 53 can swing about the first swing axis O1. In detail, the third link 53 swings in a first direction and a second direction about the first swing axis O1. When the third link 53 swings in the first direction, the lower end of the third link 53 moves in the first direction. That is, in FIG. 1, the third link 53 swings counterclockwise about the first swing axis O1. When the third link 53 swings in the second direction, the lower end of the third link 53 moves in the second direction. That is, in FIG. 1, the third link 53 swings clockwise about the first swing axis O1.

[0033] The fourth link 54 is attached to the lower unit 3 so as to be able to swing. More specifically, the fourth link 54 is attached at its lower end to the lower unit 3. The fourth link 54 is also attached to a member of the lower unit 3 that moves up and down integrally with the drive wheel 32. The lower end of the fourth link 54 is configured to move in the up and down direction integrally with the lower unit 3. In this embodiment, the fourth link 54 is attached to a shaft that supports the drive wheel 32.

[0034] The fourth link 54 extends upward in the first direction from the lower unit 3. That is, an upper end of the fourth link 54 is disposed in the first direction relative to a lower end of the fourth link 54.

[0035] The fourth link 54 can swing about the second swing axis O2. In particular, the fourth link 54 swings in a first direction and a second direction about the second swing axis O2. When the fourth link 54 swings in the first direction, the upper end of the fourth link 54 moves in the first direction. That is, in FIG. 1, the fourth link 54 swings clockwise about the second swing axis O2. When the fourth link 54 swings in the second direction, the upper end of the fourth link 54 moves in the second direction. That is, in FIG. 1, the fourth link 54 swings counterclockwise about the second swing axis O2.

[0036] The second joint 56 connects the third link 53 and the fourth link 54. More specifically, the second joint 56 connects a lower end of the third link 53 and an upper end of the fourth link 54. The third link 53 and the fourth link 54 are connected by the second joint 56 so as to be rotatable with each other.

[0037] The second joint 56 is disposed in a first direction with respect to a virtual line L connecting the first oscillation axis O1 and the second oscillation axis O2. The second joint 56 is disposed so as to be movable in the first and second directions. When the second joint 56 moves in the second direction, that is, when the second joint 56 approaches the virtual line L, the first oscillation axis O1 and the second oscillation axis O2 move in directions away from each other. Note that the second joint 56 does not move beyond the virtual line L in the second direction.

[0038] The third joint 57 connects the first link 51 and the third link 53. In detail, the third joint 57 connects an upper end of the first link 51 and an upper end of the third link 53. The first link 51 and the third link 53 are connected by the third joint 57 to be rotatable with respect to each other.

[0039] The third joint 57 is disposed at the same position as the first oscillation axis O1. The third joint 57 is attached to the upper unit 2 so as to move integrally therewith in the up and down direction.

[0040] The fourth joint 58 connects the second link 52 and the fourth link 54. In detail, the fourth joint 58 connects a lower end of the second link 52 and a lower end of the fourth link 54. The second link 52 and the fourth link 54 are connected by the fourth joint 58 so as to be rotatable with respect to each other.

[0041] The fourth joint 58 is disposed at the same position as the second oscillation axis O2. The fourth joint 58 is attached to the lower unit 3 so as to move integrally therewith in the up and down direction.

[0042] The operating member 6 is disposed adjacent to the link mechanism 5 in the axial direction (perpendicular to the plane of the paper in FIG. 1). The operating member 6 is configured to operate the link mechanism 5. The operating member 6 is configured so that a human force in a first direction or a second direction is input by a user. For example, a handle for the user to grip is attached to the tip of the operating member 6. When the user pulls the operating member 6 in the first direction to make the cart 200 travel in the first direction, a human force in the first direction is input to the operating member 6. When the user pushes the operating member 6 in the second direction to make the cart 200 travel in the second direction, a human force in the second direction is input to the operating member 6.

[0043] The operating member 6 is configured to move the first joint 55 in a first direction when a human force is input in the first direction. In detail, the operating member 6 has a first contact surface 61. The first contact surface 61 faces the first direction. The operating member 6 has a slit hole 60 extending along the first direction and the second direction. Of the inner wall surfaces that define the slit hole 60, the surface that faces the first direction is the first contact surface 61.

[0044] The first contact surface 61 faces the first joint 55 or a member that moves in the first direction integrally with the first joint 55. For example, the first joint 55 extends in the axial direction from the first link 51 or the second link 52. A part of the first joint 55 is disposed in a slit hole 60 of the operating member 6.

[0045] The operating member 6 is configured to move the second joint 56 in the second direction when a human force is input in the second direction. In detail, the operating member 6 has a second abutment surface 62. The second abutment surface 62 faces the second direction. Of the inner wall surfaces that define the slit hole 60, the surface that faces the second direction is the second abutment surface 62.

[0046] The second contact surface 62 faces the second joint 56 or a member that moves in the second direction integrally with the second joint 56. For example, the second joint 56 extends in the axial direction from the third link 53 or the fourth link 54. A part of the second joint 56 is disposed in a slit hole 60 of the operating member 6.

[0047] The drive unit 100 configured as described above operates as follows. First, when a user wants to move the cart 200 in a first direction, the user pulls the operating member 6 in the first direction. As a result, a human force in the first direction is input to the operating member 6, and the first contact surface 61 comes into contact with the first joint 55.

[0048] Here, if the first oscillation axis O1 and the second oscillation axis O2 were allowed to move freely, the first joint 55 would move in a first direction, as shown by the dotted line in Figure 2, the first oscillation axis O1 and the second oscillation axis O2 would move in directions away from each other, and the upper unit 2 and lower unit 3 would move in directions away from each other.

[0049] However, in reality, since the upper unit 2 and the lower unit 3 are sandwiched between the road surface and the dolly 200, when the user pulls the operating member 6 in the first direction, a force is generated to press the upper unit 2 against the dolly 200 and a force is generated to press the lower unit 3 against the road surface. This allows wheel pressure to be applied to the drive wheels 32. Here, when the dolly 200 is heavy, the force with which the user pulls the operating member 6 in the first direction increases, so the wheel pressure applied to the drive wheels 32 also increases. Also, when the dolly 200 is light, the force with which the user pulls the operating member 6 in the first direction decreases, so the wheel pressure applied to the drive wheels 32 also decreases. In this way, the drive unit 100 can change the wheel pressure applied to the drive wheels 32 according to the weight of the dolly 200.

[0050] Next, when the user wants to move the cart 200 in the second direction, the user pushes the operating member 6 in the second direction. As a result, a human force in the second direction is input to the operating member 6, and the second contact surface 62 comes into contact with the second joint 56.

[0051] Here, if the first oscillation axis O1 and the second oscillation axis O2 were allowed to move freely, the second joint 56 would move in the second direction as shown by the dotted line in Figure 3, the first oscillation axis O1 and the second oscillation axis O2 would move in directions away from each other, and the upper unit 2 and the lower unit 3 would move in directions away from each other.

[0052] However, in reality, since the upper unit 2 and the lower unit 3 are sandwiched between the road surface and the dolly 200, when the user pushes the operation member 6 in the second direction, a force is generated to press the upper unit 2 against the dolly 200 and a force is generated to press the lower unit 3 against the road surface. This allows wheel pressure to be applied to the drive wheels 32. Here, when the dolly 200 is heavy, the force with which the user pushes the operation member 6 in the second direction increases, so that the wheel pressure applied to the drive wheels 32 also increases. Also, when the dolly 200 is light, the force with which the user pushes the operation member 6 in the second direction decreases, so that the wheel pressure applied to the drive wheels 32 also decreases. In this way, even when the dolly 200 is made to travel in the second direction, the drive unit 100 can change the wheel pressure applied to the drive wheels 32 according to the weight of the dolly 200.

[0053] [Variations] Although the embodiment of the present invention has 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.

[0054] (a) In the above embodiment, the oscillation axis O1 of the first link 51 and the oscillation axis O1 of the third link 53 are the same, but they may be different from each other. For example, the oscillation axis of the third link 53 may be disposed in a first direction relative to the oscillation axis of the first link 51. Similarly, the oscillation axis of the second link 52 and the oscillation axis of the fourth link 54 may be different from each other. For example, the oscillation axis of the fourth link 54 may be disposed in a first direction relative to the oscillation axis of the second link 52. In this case, the link mechanism 5 does not need to have the third joint 57 and the fourth joint 58.

[0055] (b) In the above embodiment, the link mechanism 5 has the first to fourth links 51 to 54, but the configuration of the link mechanism 5 is not limited to this. For example, the link mechanism 5 may have the first link 51 and the second link 52, but may not have the third link 53 and the fourth link 54.

[0056] (c) As shown in FIG. 4, the drive unit 100 may have a biasing member 7. The biasing member 7 biases the upper unit 2 and the lower unit 3 in a direction away from each other. The biasing member 7 is, for example, a compression spring. The biasing member 7 applies an initial load to the drive wheel 32. The first link 51 and the third link 53 are attached to a part of the upper unit 2 so as to be able to swing. The second link 52 and the fourth link 54 are attached to a part of the lower unit 3 so as to be able to swing.

[0057] In this manner, when the drive unit 100 has a biasing member 7, the drive unit 100 may be configured so that the amount of expansion and contraction of the link mechanism 5 in the vertical direction and the amount of expansion and contraction of the biasing member 7 in the vertical direction are the same value, as in Figure 4, or the drive unit 100 may be configured so that the amount of expansion and contraction of the link mechanism 5 in the vertical direction and the amount of expansion and contraction of the biasing member 7 in the vertical direction are different values, as in Figure 5.

[0058] (d) In the above embodiment, it has been described that pulling the drive unit 100 causes it to move in the first direction, and pushing the drive unit 100 causes it to move in the second direction, but the method of using the drive unit 100 is not limited to this. For example, as shown in FIG. 6, the user may be positioned in the second direction relative to the drive unit 100. In this case, the operating member 6 extends from the link mechanism 5 in the second direction. Pulling the drive unit 100 causes it to move in the second direction, and pushing the drive unit 100 causes it to move in the first direction.

[0059] 7, the upper unit 2 may have a main body 21 and an attachment portion 22. The main body 21 is attached to the lower unit 3 so as to be able to swing up and down about a third swing axis O3. In this manner, the main body 21 swings up and down relative to the lower unit 3, so that the upper unit 2 and the lower unit 3 can move up and down relative to each other.

[0060] The mounting portion 22 is movable in the up-down direction relative to the main body portion 21. The first link 51 and the third link 53 are attached to the mounting portion 22 so as to be able to swing. The upper ends of the first link 51 and the third link 53 move in the up-down direction integrally with the mounting portion 22. The upper ends of the first link 51 and the third link 53 are supported so as to be movable in the up-down direction relative to the lower unit 3. Specifically, the frame 31 of the lower unit 3 has a groove 311 extending in the up-down direction, and the third joint 57 is disposed in the groove 311 so as to be able to move in the up-down direction.

[0061] 7, the drive wheels 3 do not have to be disposed below the carriage 200. In this case, the upper unit 2 extends toward the carriage 200.

[0062] 7, the biasing member 7 may be attached to the frame 31 and bias the drive wheel 32 via the frame 31. In addition, the lower ends of the second link 52 and the fourth link 54 may be attached to the frame 31 so as to be able to swing. [Explanation of symbols]

[0063] 2: Upper unit 3: Lower unit 32: Drive wheel 4: Electric motor 5: Link mechanism 51: First link 52: Second link 53: Third link 54: 4th link 55: First joint 56: 2nd joint 6: Operation parts 61: 1st contact surface 62:Second contact surface 7: Pressurizing member 100: Drive unit

Claims

1. A drive unit configured to be attached to a moving body capable of moving in a first direction, An upper unit configured to be attached to a moving body; a lower unit having a drive wheel and arranged to be movable in a vertical direction relative to the upper unit; A drive source configured to drive the drive wheels; a link mechanism including: a first link swingably attached to the upper unit and extending downward from the upper unit in a second direction opposite to the first direction; a second link swingably attached to the lower unit and extending upward from the lower unit in the second direction; and a first joint connecting the first link and the second link; an operating member configured to move the first joint in the first direction when a human force is input in the first direction; A drive unit comprising:

2. The link mechanism includes: a third link pivotably attached to the upper unit and extending downward from the upper unit in the first direction; a fourth link pivotably attached to the lower unit and extending upward from the lower unit in the first direction; a second joint connecting the third link and the fourth link; having The operating member is configured to move the second joint in the second direction when a human force is input in the second direction.

2. A drive unit according to claim 1.

3. Further, a biasing member is provided to bias the upper unit and the lower unit in directions away from each other.

2. A drive unit according to claim 1.

4. The operating member has a first contact surface facing the first direction, The first abutment surface faces the first joint or a member that moves integrally with the first joint in a first direction.

2. A drive unit according to claim 1.

5. The operating member has a second contact surface facing the second direction, The second contact surface faces the second joint or a member that moves integrally with the second joint in the second direction. A drive unit according to claim 2.

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