JP2008213573A - Differential caster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a differential caster capable of certainly securing an electric motor on a supporting shaft and providing favorable driving force. <P>SOLUTION: This differential caster to fix a pair of the electric motors on an auxiliary shaft 10 through an electric motor mounting plate 31 is provided with a locking screw 63 to regulate rotation of the electric motor mounting plate 31 in the circumferential direction on the auxiliary shaft 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a differential caster having a pair of wheels.

2. Description of the Related Art Conventionally, there are known an electric wheelchair that can be self-propelled using a differential caster, a transport vehicle that transports parts stored in a warehouse, and the like.
This differential caster includes a pair of drive wheels at one end of a support shaft that is rotatably attached to a chassis portion (vehicle body). These drive wheels each have a built-in electric motor for miniaturization, and each drive wheel can be driven independently. And the traveling direction of an electric wheelchair or a conveyance vehicle is made changeable by the rotation difference of each drive wheel (for example, refer patent document 1).
JP 2004-90903 A

  By the way, in the differential type caster, a hollow portion (through hole) intersecting with the axial direction is provided at one end of the support shaft, and an electric motor mounting plate for fixing the electric motor of the driving wheel is provided here. There is something. The electric motors are fastened and fixed to the electric motor mounting plates with bolts.

Here, when the electric motor is tightened with a bolt, the electric motor is pulled to the electric motor mounting plate side (support shaft side). At this time, a frictional resistance is generated between the electric motor and the support shaft, and the rotation (rotation in the circumferential direction) of the electric motor is regulated by this frictional force.
In this way, if the electric motor is fixed to the support shaft using the electric motor mounting plate, there is no need to provide a fixing portion for fixing the electric motor on the outer peripheral surface of the support shaft. Can be achieved.

  However, since the electric motor mounting plate is loosely fitted in the hollow portion, when the fastening force of the bolt that fastens the electric motor is reduced, the frictional force between the electric motor and the support shaft is also weakened. For this reason, there exists a subject that an electric motor may rotate and there exists a possibility that a drive wheel may not drive efficiently.

  Accordingly, the present invention has been made in view of the above-described circumstances, and provides a differential caster that can securely fix an electric motor to a support shaft and obtain a good driving force. It is.

In order to solve the above-described problems, the invention described in claim 1 includes a mounting plate, a main shaft rotatably provided on the mounting plate, and a hollow portion extending from one end of the main shaft in a direction intersecting the main shaft. And a pair of electric motors provided at both ends of the auxiliary shaft and fixed to each other via the electric motor mounting plates. A differential caster comprising a pair of wheels respectively linked to the output shafts of the pair of electric motors, wherein a restriction member for restricting the rotation of the electric motor mounting plate in the circumferential direction is provided on the auxiliary shaft. It is characterized by that.
In this case, as in the invention described in claim 2, a receiving portion that can receive the restriction member may be formed on the electric motor mounting plate.
With this configuration, since the electric motor mounting plate provided in the hollow portion of the support shaft can be prevented from rotating in the circumferential direction, the electric motor can be prevented from rotating and securely fixed to the support shaft. be able to.

The invention described in claim 3 is characterized in that a lead wire routing portion for routing a lead wire connected to the electric motor is formed on the electric motor mounting plate.
With this configuration, it is possible to route the lead wire in the auxiliary shaft of the support shaft.

  According to the first and second aspects of the present invention, since the electric motor mounting plate provided in the hollow portion of the support shaft can be prevented from rotating in the circumferential direction, the electric motor can be prevented from rotating. It can be securely fixed to the spindle. Therefore, it is possible to provide a differential caster that obtains a good driving force.

  According to the third aspect of the present invention, since the lead wire can be routed in the auxiliary shaft of the support shaft, further miniaturization of the differential caster can be achieved.

Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the differential caster 1 is attached together with free casters 3 and 4 to the lower surface (lower side in FIG. 1) of a vehicle body 2 used as an electric wheelchair or a transport vehicle. The upper surface of the vehicle body 2 is a space for placing a chair and parts. In addition, a hole 2 a is formed in the vehicle body 2 at a portion corresponding to the installation position of the differential caster 1. The hole 2 a is for preventing interference between the vehicle body 2 and the differential caster 1.

As shown in FIG. 2, the differential caster 1 includes an attachment plate 5 for attaching the differential caster 1 to the vehicle body 2. The mounting plate 5 is provided with two bearings 6 and 7 in the center in the radial direction, and a support shaft 8 is rotatably supported thereon.
The support shaft 8 is provided at the main shaft 9 extending along the vertical direction (up and down direction in FIG. 2) and at the lower end (lower side in FIG. 2) of the main shaft 9 and along the horizontal direction (left and right direction in FIG. 2). The extending auxiliary shaft 10 is integrally formed. The main shaft 9 and the sub shaft 10 are formed with hollow portions 9a and 10a penetrating along the respective axial directions. These hollow portions 9a and 10a are for routing a power supply line 30 for supplying power to the electric motor 12, and are in a state of communicating with each other.

  A hollow shaft encoder 11 for detecting the rotation angle of the support shaft 8 is provided on the upper end side of the main shaft 9 (upper side in FIG. 2). In the hollow shaft encoder 11, the movement of the support shaft 8 in the axial direction is restricted by a hollow collar 33 provided on the upper end side and a receiving seat 34 provided on the lower end side. The receiving seat 34 is fastened and fixed to the mounting plate 5 with bolts 54.

  On the other hand, a pair of wheels 35 and 35 are rotatably attached to both ends of the auxiliary shaft 10 by bearings 36 and 36, respectively. Each wheel 35, 35 has a bottomed cylindrical wheel 37 that is rotatably supported by the countershaft 10, and the opening of the wheel 37 is covered with a lid portion 38, and a floor surface or the like is provided on the outer peripheral portion of the wheel 37. A tire 39 that contacts the ground is fixed with a tapping screw 40. One electric motor 12 is built in the internal space formed by the wheel 37 and the lid portion 38 so that the wheels 35 and 35 can be driven to rotate independently.

Here, the electric motor 12 is fastened and fixed by bolts 32 to an electric motor mounting plate 31 provided at a substantially axial center (the center in FIG. 2) of the hollow portion 10 a of the auxiliary shaft 10.
As shown in FIGS. 2 and 3, the electric motor mounting plate 31 is formed to correspond to a cross-sectional shape orthogonal to the axial direction of the hollow portion 10 a in plan view. The electric motor mounting plate 31 is provided with four female screw portions 60a, 60b, 60c, 60d. The female screw portions 60a, 60b, 60c, and 60d are used to fasten and fix the electric motors 12 and 12, respectively.

  That is, two of the four female screw portions 60a, 60b, 60c, and 60d are screwed into the bolt 32 from the left side in FIG. 2, and the other two are screwed into the bolt 32 from the right side in FIG. Thus, the two electric motors 12 and 12 are fastened and fixed, respectively. 3, in order to fasten and fix one electric motor 12 with the female screw portion 60a located at the lower center and the female screw portion 60c located on the left side, the female screw portion 60b located at the center and the right side It is desirable to use the female screw portion 60d located at the position to fasten and fix the other electric motor 12.

  Notch portions 61, 61 are formed at two positions obliquely from the center toward the lower outer side (left-right direction in FIG. 3) slightly below the center of the electric motor mounting plate 31 (opposite to the main shaft 9). . End portions (bottom portions) 61a of the notches 61 and 61 are formed in an arc shape.

  On the other hand, on the peripheral wall 10b of the auxiliary shaft 10, female screw portions 62, 62 are formed at portions corresponding to the cutout portions 61, 61, and set screws 63 are screwed therein. The set screw 63 penetrates the peripheral wall 10b of the auxiliary shaft 10 from the outside to the inside, and is interposed in the notch 61 of the electric motor mounting plate 31. That is, the notch 61 of the electric motor mounting plate 31 is formed so as to receive the set screw 63.

The width E1 of the notch 61 is preferably set so as to substantially match the diameter of the set screw 63.
Further, a flattening portion 64 is formed on the main shaft 9 side of the electric motor mounting plate 31. The flattening portion 64 has a function as a routing portion for routing the power supply line 30. That is, the flattening portion 64 forms a gap S between the inner peripheral surface of the hollow portion 10 a and the flattening portion 64, and the power supply line 30 is routed in the gap S.

As shown in FIG. 2, the electric motor 12 includes a bracket 15 fixed to the countershaft 10 of the support shaft 8 and a bottomed cylindrical yoke 13 fixed to the bracket 15. 13 supports the armature 14 so as to be rotatable and along the horizontal direction.
The bracket 15 is integrally formed with a cylindrical portion 24 fitted into the hollow portion 10a of the countershaft 10 and a flange portion 25 extending radially outward from the armature 14 side (left and right direction in FIG. 2) end of the cylindrical portion 24. It is molded.

  A bolt hole 55 for screwing the bolt 32 is formed in the peripheral wall of the cylindrical portion 24, and a through hole 24a penetrating in the axial direction of the cylindrical portion 24 is formed on the main shaft 9 side (upper side in FIG. 2). Has been. The through hole 24 a is for inserting the power supply line 30. Further, a bearing 26 is provided in the radial center on the armature 14 side (left and right direction in FIG. 2) of the cylindrical portion 24, and one end of the output shaft 17 of the armature 14 is supported rotatably.

  As shown in FIGS. 2 and 4, the flange portion 25 is formed in a substantially hat shape so as to cover the opening of the yoke 13, and the end portion 25 a has the auxiliary shaft 10 side (see FIG. 2). 4 on the left side). Due to the stepped portion 47, the flange portion 25 comes into contact only with the inner rings of the bearings 36 provided at both ends of the auxiliary shaft 10.

  Therefore, the bracket 15 is pulled toward the auxiliary shaft 10 by tightening the bolt 32. However, since the step portion 47 is formed in the flange portion 25, the rotation of the outer ring of the bearing 36 may be hindered. Absent. Moreover, when the flange portion 25 is pressed against the inner ring of the bearing 36, friction resistance is generated in both of them, and the bracket 15 can be prevented from rotating in the circumferential direction due to this frictional force. Needless to say, the greater the fastening force of the bolt 32, the greater the frictional force.

On the other hand, a holder stay 48 is attached to the armature 14 side of the flange portion 25 (the right side in FIG. 4). The holder stay 48 is provided with a plurality of brush holders 28, and brushes 29 are respectively housed in the brush holders 28 so as to be able to appear and retract.
One end of a power supply line 30 is electrically connected to these brushes 29. One end of the power supply line 30 is routed from the outside to the brush 29 through the hollow portions 9a and 10a of the support shaft 8 and the through hole 24a of the cylindrical portion 24, while the other end is connected to an external power source (not shown). It is connected.

The opening of the yoke 13 is fixed to the peripheral edge of the flange portion 25. A plurality of permanent magnets 27 are fixed to the inner peripheral surface of the yoke 13 with an adhesive or the like at equal intervals in the circumferential direction.
An insertion hole 18 for inserting the output shaft 17 of the armature 14 is formed in the end portion (bottom portion) 16 of the yoke 13 in the center in the radial direction, and a bearing 19 is provided in the insertion hole 18. This bearing 19 is for rotatably supporting the other end side of the output shaft 17 of the armature 14.

The armature 14 includes an armature core 20 that is externally fixed to the output shaft 17, an armature coil 21 wound around the armature core 20, and a commutator disposed on one end side (center side in FIG. 2) of the armature core 20. Commutator) 22.
A plurality of segments 23 made of a conductive material are attached to the outer peripheral surface of the commutator 22.

The segments 23 are made of plate-like metal pieces that are long in the axial direction, and are fixed in parallel at equal intervals along the circumferential direction while being insulated from each other. A winding start end and a winding end end of the armature coil 7 are connected to each segment 23 by fusing.
The segment 23 is in sliding contact with the tip of the brush 29. As a result, power from the outside is supplied to the commutator 22 via the power supply line 30 and the brush 29.

The other end side of the output shaft 17 protrudes outward from an insertion hole 18 formed in the end portion 16 of the yoke 13. A gear portion 41 is formed on the outer peripheral surface of the protruding portion of the output shaft 17 and meshed with the speed reduction mechanism 42.
The speed reduction mechanism 42 includes a stepped spur gear 43 that is coaxially provided with two spur gears that are engaged with the output shaft 17 and have different numbers of teeth, and an internal tooth that is integrally formed with the lid portion 38 of the wheel 35 and is engaged with the stepped spur gear 43. And a gear 45. The stepped spur gear 43 is rotatably supported by a support shaft (not shown) protruding from the end portion 16 of the yoke 13. The unillustrated support shaft passes through the stepped gear 43 and protrudes toward the lid portion 38 of the wheel 35. A support member 44 is attached to a portion where the support shaft protrudes. The support member 44 rotatably supports the lid portion 38 via a bearing 46. Thus, the output shaft 17 of the armature 14 is in a state of being linked to the wheel 35 via the speed reduction mechanism 42.

  In the differential caster 1 configured in this way, when both wheels (the pair of wheels 35 and 35 in FIG. 2) are driven at the same rotational speed, the vehicle body 2 goes straight or reverse (the front side of the page in FIG. 2, Or the back side). When the wheels 35 and 35 are driven at different rotational speeds, or when one wheel 35 is driven and the other wheel 35 is stopped, the vehicle body 2 turns rightward or leftward. It has become.

  Therefore, according to the above-described embodiment, the notch 61 is provided in the electric motor mounting plate 31 provided in the hollow portion 10a of the countershaft 10, and the setscrew 63 is screwed into the countershaft 10, and the setscrew 63 is interposed in the notch 61. For this reason, the rotation of the electric motor 12 can be prevented by preventing the electric motor mounting plate 31 from rotating in the circumferential direction. Therefore, it is possible to provide the differential caster 1 that can reliably fix the electric motor 12 to the auxiliary shaft 10 of the support shaft 8 and obtain a good driving force.

Further, for example, even when the fastening force of the bolt 32 for fastening and fixing the electric motor 12 is reduced, the electric motor 12 can be easily prevented from rotating by using the set screw 63, so that the fail safe (fail safe) ) Functions can be added at low cost.
Here, fail-safe means that a failure of a part or a system is surely a safe side, or at least almost certainly a safe side (that is, a possibility of a dangerous side failure is extremely low). Means that.

  Further, a flattening portion 64 is formed on the main shaft 9 side of the electric motor mounting plate 31, and the power supply line 30 is routed by forming a gap S between the inner peripheral surface of the hollow portion 10a and the flattening portion 64. can do. Therefore, the hollow portions 9a and 10a formed in the main shaft 9 and the sub shaft 10 are not blocked by the electric motor mounting plate 31, and as a result, the power supply line 30 can be routed inside the support shaft 8. It becomes possible. Therefore, further miniaturization of the differential caster 1 can be achieved.

The present invention is not limited to the above-described embodiment, and includes various modifications made to the above-described embodiment without departing from the spirit of the present invention.
Further, in the above-described embodiment, the case where the cutout portion 61 is formed in the electric motor mounting plate 31 has been described. However, the present invention is not limited to this. The inserted set screw 63 may be formed so as to be receivable.

Further, in the above-described embodiment, the case where the cutout portion 61 is formed in the electric motor mounting plate 31 has been described. However, the present invention is not limited to this, and the set screw 63 screwed into the countershaft 10 is directly connected to the electric motor. You may make it press on the surrounding surface of the attachment plate 31. FIG. In this case, it is desirable that the set screw 63 has a tapered tip.
And in the above-mentioned embodiment, although the differential type caster 1 demonstrated the case where it was attached with the free casters 3 and 4 to the lower surface of the vehicle body 2 of an electric wheelchair or a conveyance vehicle, it is not restricted to this, Only the differential caster 1 may be attached to the lower surface of the vehicle body 2.

  Further, the case where the output shaft 17 of the armature 14 is linked to the wheel 35 via the speed reduction mechanism 42 has been described. However, the present invention is not limited to this, and the planetary speed reduction mechanism can be used instead of the speed reduction mechanism 42. Also good. In this case, the stepped gear 43 meshes with the output shaft 17 to rotate and may be replaced with a planetary gear that can revolve around the output shaft 17.

It is a perspective view which shows the attachment state of the differential type caster in embodiment of this invention. It is a longitudinal cross-sectional view of the differential type caster in the embodiment of the present invention. It is sectional drawing which follows the AA line of FIG. It is a partial expanded sectional view of the differential type caster in the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Differential type caster 5 Mounting plate 8 Support shaft 9 Main shaft 10 Sub shaft 9a, 10a Hollow part 12 Electric motor 17 Output shaft 30 Electric power supply line (lead wire)
31 Electric motor mounting plate 35 Wheel 61 Notch (receiving part)
63 Set screw (regulator)
64 Flattening part (lead wire routing part)

Claims (3)

A mounting plate;
A support shaft comprising a main shaft rotatably provided on the mounting plate and a sub shaft having a hollow portion extending from one end of the main shaft in a direction intersecting the main shaft;
An electric motor mounting plate provided in the hollow portion;
A pair of electric motors provided at both ends of the auxiliary shaft and fixed to each other via the electric motor mounting plate;
A differential caster comprising a pair of wheels respectively linked to output shafts of the pair of electric motors,
A differential caster, characterized in that a restricting member for restricting rotation of the electric motor mounting plate in the circumferential direction is provided on the countershaft.   The differential caster according to claim 1, wherein a receiving portion capable of receiving the restricting member is formed on the electric motor mounting plate.   The differential caster according to claim 1, wherein a lead wire routing portion for routing a lead wire connected to the electric motor is formed on the electric motor mounting plate.

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