JP2008213571A - Differential type caster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a differential type caster capable of obtaining appropriate gripping force by followability to irregularity, and realizing stable travelling. <P>SOLUTION: This differential type caster consists of a mounting plate 5, a main spindle 9 supported in the mounting plate 5 rotatably, a sub spindle 10 provided in one end of the main spindle 9 crossingly therewith oscillatingly, a pair of electric motors 12, 12 provided in both ends of the sub spindle 10, and a pair of wheels 35, 35 respectively engaged with the output shafts 17, 17 of the electric motors 12, 12. <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

  However, in the above-described prior art, since the pair of driving wheels are fixed to the support shaft in a rigid manner, when the traveling road surface (floor surface) has a large unevenness, the unevenness cannot be followed, and one wheel floats. It may end up. For this reason, there is a problem that the driving wheels cannot obtain an appropriate grip force, which may hinder the traveling of the differential caster or may not be able to perform a stable traveling.

  Therefore, the present invention has been made in view of the above-described circumstances, and provides a differential caster that can obtain an appropriate grip force by following unevenness and can realize stable traveling. is there.

In order to solve the above-mentioned problem, the invention described in claim 1 includes a mounting plate, a main shaft rotatably supported by the mounting plate, and swinging at one end of the main shaft so as to intersect the main shaft. It is characterized by comprising a counter shaft provided in a possible manner, a pair of electric motors provided at both ends of the sub shaft, and a pair of wheels respectively linked to output shafts of the pair of electric motors.
By comprising in this way, even if it is a case where the unevenness | corrugation of a driving | running | working road surface is large, a wheel can be followed and it can be made to contact | ground to a driving | running road surface reliably.

The invention described in claim 2 is characterized in that a hollow portion is provided in at least one of the main shaft or the sub shaft, and a power supply line connected to the electric motor is routed in the hollow portion.
By comprising in this way, it can be connected to an electric motor, without arranging a power supply line in the outer peripheral surface of at least one of a spindle or a countershaft.

  According to the first aspect of the present invention, even when the road surface is uneven, the wheel can be made to follow the road surface with certainty, so that the wheel can obtain an appropriate grip force. Thus, it is possible to realize stable running of the differential caster.

  According to the second aspect of the present invention, the power supply line can be connected to the electric motor without routing the outer peripheral surface of at least one of the support shaft and the auxiliary shaft. The exposure of the power supply line can be reduced. For this reason, it is possible to prevent the power supply line from being caught in the wheel, to ensure a good driving state of the differential caster, and to improve the aesthetic appearance.

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 FIGS. 2 and 3, 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 extends along the vertical direction (vertical direction in FIG. 2) and is rotatably supported by the mounting plate 5 and a lower end (lower side in FIG. 2) of the main shaft 9. It is comprised with the countershaft 10 pivotally supported through the fulcrum pin 71 so that rocking | fluctuation is possible.

  The main shaft 9 includes a first hollow portion 9a extending in the axial direction from the upper end (upper side in FIG. 2) to the vicinity of the lower end (lower side in FIG. 2), and a lower end of the first hollow portion 9a. A second hollow portion 9b penetrating the main shaft 9 in a direction intersecting with the one hollow portion 9a is formed in series. The first hollow portion 9 a and the second hollow portion 9 b are for routing a power supply line 30 for supplying power to the electric motor 12.

  A hollow shaft encoder 11 for detecting the rotation angle of the main shaft 9 is provided on the upper end side of the main shaft 9. 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. An arc portion 70 is formed at the lower end of the main shaft 9. A fulcrum pin 71 is provided at a substantially central point of the arc portion 70.

  The auxiliary shaft 10 extends in a direction intersecting the main shaft 9 and is pivotally supported by the fulcrum pin 71 at the approximate center in the axial direction and the radial direction. The auxiliary shaft 10 is formed with a hollow portion 10a penetrating in the axial direction. This hollow portion 10 a is also used for routing the power supply line 30. Further, the auxiliary shaft 10 is formed with an insertion hole 72 at a portion corresponding to the main shaft 9, and the main shaft 9 is inserted therethrough.

  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, covers the opening of the wheel 37 with a lid portion 38, and runs on the road surface F 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.

The electric motor 12 includes a bracket 15 fixed to the auxiliary shaft 10 of the support shaft 8 and a bottomed cylindrical yoke 13 fixed to the bracket 15, and the armature 14 can be freely rotated by the bracket 15 and the yoke 13. And is supported 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 through-hole 24 a penetrating in the axial direction of the cylindrical portion 24 is formed on the peripheral wall of the cylindrical portion 24 on the main shaft 9 side (upper side in FIG. 2). 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.

  The flange portion 25 is formed in a substantially hat shape so as to cover the opening of the yoke 13, and a stepped portion 47 is formed on the end portion 25a on the auxiliary shaft 10 side (left side in FIG. 3). Has been. 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.

  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. 3). 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 9 a, 9 b, 10 a of the support shaft 8 and the through hole 24 a of the cylindrical portion 24, while the other end is the upper end of the main shaft 9. It is pulled out from the collar 33 provided in the and is connected to an external power source (not shown).

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 support shaft 8 that is rotatably supported by the mounting plate 5 extends along the vertical direction (vertical direction in FIG. 2) and is rotatably supported by the mounting plate 5. The main shaft 9 is composed of a main shaft 9 and a sub shaft 10 pivotally supported by a lower end (lower side in FIG. 2) of the main shaft 9 via a fulcrum pin 71. That is, the main shaft 9 is rotatable in this circumferential direction, and the auxiliary shaft 10 is swingable in the circumferential direction of the fulcrum pin 71. For this reason, the wheel 35 can be made to follow according to the uneven | corrugated shape of the driving | running | working road surface F (refer FIG. 2), and the wheel 35 can be reliably grounded on the driving | running | working road surface F. Therefore, the wheel 35 can obtain an appropriate grip force, and the differential caster 1 can be stably driven.
In addition, since the arc portion 70 is formed at the lower end of the main shaft 9, even if the sub shaft 10 is largely inclined, the interference between the main shaft 9 and the sub shaft 10 can be allowed to some extent. For this reason, even if the unevenness | corrugation of the traveling road surface F is large, the wheel 35 can be reliably grounded to the traveling road surface F.

  A first hollow portion 9 a and a second hollow portion 9 b are formed on the main shaft 9 of the support shaft 8, and a hollow portion 10 a is formed on the auxiliary shaft 10. Therefore, the external power supply and the electric motor 12 can be electrically connected without routing the power supply line 30 on the outer peripheral surface of the support shaft 8. Therefore, it is possible to prevent the electric power supply line 30 from being caught in the wheel 35 and to ensure a good driving state of the differential caster 1. Further, the aesthetic appearance can be improved by arranging the power supply line 30 inside the support shaft 8.

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 hollow collar 33 is provided on the upper end side of the main shaft 9 and the power supply line 30 is drawn out from here is described. However, as shown in FIG. A slip ring 50 may be provided.

Here, the slip ring 50 is a so-called rotary connector that supplies electric power from the fixed side to the rotating side, and from the external power source (not shown, fixed side) attached to the vehicle body 2 to the electric motor 12 (rotating) of the wheel 35. Used to supply power to the side).
As described above, when the slip ring 50 is provided, the fixing portion 51 constituting the slip ring 50 is fastened and fixed to the collar 33 by the bolt 53.

Then, the other end of the first power supply line 30a, one end of which is connected to an external power supply (not shown), is electrically connected to the movable part 52, while the other end of the second power supply line 30b is connected to the fixed part 51. While being electrically connected, the other end is electrically connected to the brush 29 of the electric motor 12.
By doing so, for example, even when the differential caster 1 is continuously rotated in the same direction, the first power supply line 30a and the second power supply line 30b can be prevented from being twisted. For this reason, disconnection due to twisting of the first power supply line 30a and the second power supply line 30b can be prevented, and the differential caster 1 with higher reliability can be provided.

  In the above-described embodiment, the first hollow portion 9a and the second hollow portion 9b are formed on the main shaft 9 of the support shaft 8, and the hollow portion 10a is formed on the auxiliary shaft 10. It is not limited, and it is sufficient that a hollow portion is formed in at least one of the main shaft 9 and the sub shaft 10.

Further, in the above-described embodiment, the case where the power supply line 30 is routed in the hollow portions 9a, 9b, 10a of the support shaft 8 has been described. However, the present invention is not limited to this. 12 is attached with a sensor (a sensor for detecting the rotation angle of the output shaft 17 and the rotation speed of the output shaft 17) for recognizing the operation state of the sensor. You may search.
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 a partial expanded sectional view of the differential type caster in the embodiment of the present invention. It is a longitudinal cross-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 9 Main shaft 9a First hollow part (hollow part)
9b Second hollow part (hollow part)
DESCRIPTION OF SYMBOLS 10 Subshaft 10a Hollow part 12 Electric motor 17 Output shaft 30 Electric power supply line 30a First electric power supply line (electric power supply line)
30b Second power supply line (power supply line)
35 wheels

Claims (2)

A mounting plate;
A main shaft rotatably supported by the mounting plate;
An auxiliary shaft provided at one end of the main shaft so as to be able to swing so as to intersect the main shaft;
A pair of electric motors provided at both ends of the countershaft;
A differential caster comprising a pair of wheels respectively linked to output shafts of the pair of electric motors. A hollow portion is provided in at least one of the main shaft or the sub shaft,
The differential caster according to claim 1, wherein a power supply line connected to the electric motor is routed in the hollow portion.

Images