JP2000337401A - Electromagnetic clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and the consumption power of an electromagnetic clutch having a meshing engaging member. SOLUTION: When an electromagnetic 75 is demagnetized, a first dog 721 of a lock gear 72 slidably supported at an axle shaft 59 is engaged with a second dog 441 of a final gear 44 through the elastic repulsive force of a spring 80 and an electromagnetic clutch 73 is engaged. When the electromagnetic 75 is excited, a fiction disc 77 is non-rotatably attracted to the electromagnet 75, and since a cam member 78 relatively rotatably and slidably connected to the friction disc 77 is non-rotatably constrained, relative rotation is generated between the lock gear 72 rotating togetherwith the axle shaft 59 and a cam member 78. As a result, the moving cam 722 of the lock gear 72 receives a reaction force from the fixed cam 781 of the cam member 78, the lock gear 72 is slid in a non-engaging direction against the elastic repulsive force of the spring 80 and attracted to the electromagnet 75, and the electromagnetic clutch 73 is released from engagement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic clutch which transmits a driving force by driving a meshing engagement member urged in one direction by a spring in the other direction by an electromagnet, or interrupts the transmission of the driving force. About.

[0002]

2. Description of the Related Art Such an electromagnetic clutch is, for example,
It is already known as described in JP-A-111394.

[0003]

In an electromagnetic clutch which transmits a driving force by contact of a frictional engagement member and interrupts transmission of a driving force by separation of the frictional engagement member, a frictional engagement driven by an electromagnet is provided. Since the stroke of the member is small, a small and small output magnet can be used as the electromagnet. On the other hand, in the case of an electromagnetic clutch that needs to transmit a large driving force, a dog clutch that employs a meshing engagement member having a large unevenness in place of the friction engagement member is employed. Since the dog clutch has a large stroke of the meshing engagement member from a position where the dog is engaged to a position where the dog is disengaged, it is necessary to use a large and high-power electromagnet for attracting the meshing engagement member. This has been a cause of increasing the size of the electromagnetic clutch and increasing power consumption.

The present invention has been made in view of the above circumstances, and has as its object to reduce the size and power consumption of an electromagnetic clutch having a meshing engagement member.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, a meshing engagement member supported on the outer periphery of a shaft member so as to be slidable in the axial direction is provided. A spring that enables transmission of a driving force by sliding an engagement member in an engagement direction, and transmission of a driving force by sliding a meshing engagement member in a non-engagement direction against the elastic force of the spring. In an electromagnetic clutch in which an electromagnet for shutting off is arranged coaxially, a cam member having a fixed cam that is rotatably arranged on the outer periphery of the meshing engagement member and can be engaged with a movable cam formed on the meshing engagement member, A friction plate which is arranged to face the electromagnet and is connected to the cam member so as to be relatively non-rotatable and slidable in the axial direction. Movable by restraining An electromagnetic clutch has been proposed, characterized in that the engagement member is slid in the non-engagement direction against the resilience of the spring and is attracted to the electromagnet by a reaction force received by the cam member from the fixed cam of the cam member. You.

According to the above configuration, when the electromagnet is demagnetized, the meshing engagement member slidably supported by the shaft member slides in the engagement direction by the spring force of the spring to transmit the driving force. When the electromagnet is excited, the friction member plate is attracted to the electromagnet so that it cannot rotate, and the cam member connected to the friction plate so as to be relatively nonrotatable and slidable in the axial direction is restrained from rotating, so that the meshing member rotates with the shaft member. Relative rotation occurs between the engagement member and the cam member. As a result, the movable cam of the engagement member receives a reaction force from the fixed cam of the cam member, and the engagement member slides in the non-engagement direction against the elastic force of the spring and is attracted to the electromagnet. You. In this manner, by merely attracting the friction plate with the electromagnet, the movable cam can slide in the non-engagement direction by the reaction force received from the fixed cam, approach the electromagnet, and reliably attract the attraction. Therefore,
Even if the spring force of the spring is set to be large so as to enable the reliable engagement of the meshing engagement member, the electromagnet is small and the power consumption is small, so that the meshing engagement member is reliably slid in the non-engaging direction. Can be.

According to the second aspect of the present invention,
In addition to the configuration according to claim 1, an idler bush that rotates integrally with the shaft member with a gap between the friction plate and the friction plate is disposed between the friction plate and the engagement engagement member, and the engagement engagement attracted to the electromagnet. There has been proposed an electromagnetic clutch in which the joining member is held by an idler bush.

According to the above construction, when the electromagnet is excited, the meshing engagement member does not directly contact the friction plate, but rotates integrally with the shaft member to form the idle bush having a gap between the friction plate and the shaft member. Since the abutment is maintained in contact, the friction plate attracted to the electromagnet and restricted in rotation can be prevented from directly abutting and sliding with the meshing engagement member rotating integrally with the shaft member.

According to the third aspect of the present invention,
In addition to the configuration of the second aspect, an electromagnetic clutch is proposed in which a spring is housed between the inner peripheral surface of the meshing engagement member and the idling bush and the outer peripheral surface of the shaft member.

According to the above construction, since the spring is housed between the inner peripheral surface of the meshing engagement member and the idling bush and the outer peripheral surface of the shaft member, the spring is compactly arranged to reduce the size of the electromagnetic clutch. Can be.

According to the invention described in claim 4,
A meshing engagement member axially slidably supported on the outer periphery of the shaft member, a spring that slides the meshing engagement member in the non-engagement direction to interrupt transmission of driving force, and a spring that meshes with the spring. In an electromagnetic clutch in which an electromagnet is disposed coaxially with an electromagnet which slides in an engagement direction against a resilient force of the engagement member to enable transmission of a driving force, the electromagnetic clutch is rotatably disposed on an outer periphery of the engagement engagement member. A cam member having a fixed cam engageable with a movable cam formed on an engagement member, and a friction plate disposed to face the electromagnet and connected to the cam member so as to be relatively non-rotatable and axially slidable. The frictional plate is non-rotatably attracted by excitation of the electromagnet and the cam member is restrained from rotating, so that the movable cam receives the reaction force received from the fixed cam of the cam member, thereby causing the meshing engagement member to resilient the spring. In charge of Electromagnetic clutch, characterized in that adsorbed to the electromagnet is slid in the direction is proposed.

According to the above configuration, when the electromagnet is demagnetized, the meshing engagement member slidably supported by the shaft member slides in the non-engagement direction by the spring force of the spring, thereby interrupting the transmission of the driving force. When the electromagnet is excited, the friction plate is non-rotatably attracted to the electromagnet, and the cam member connected to the friction plate so as to be relatively non-rotatable and slidable in the axial direction is constrained non-rotatably. Relative rotation occurs between the engagement member and the cam member. As a result, the movable cam of the meshing engagement member receives a reaction force from the fixed cam of the cam member,
The meshing engagement member slides in the engagement direction against the elastic force of the spring and is attracted to the electromagnet. Just by attracting the friction plate with the electromagnet in this manner, the movable cam slides the engagement member in the engagement direction by the reaction force received from the fixed cam,
It can be surely attracted by approaching the electromagnet. Therefore, even if the spring force of the spring is set to be large in order to surely release the engagement of the meshing engagement member, the meshing engagement member is reliably slid in the engagement direction by the small and low power consumption electromagnet. be able to.

The left axle shaft 59 and the input shaft 104 of the embodiment correspond to the shaft member of the present invention, and the lock gear 72 of the embodiment corresponds to the meshing engagement member of the present invention.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 6 show a first embodiment of the present invention. FIG. 1 is an overall side view of an electric wheelchair provided with an electromagnetic clutch according to the first embodiment, and FIG. FIG. 3 is an enlarged sectional view taken along line 3-3 of FIG. 1, FIG. 4 is an enlarged view of a main part of FIG. 3, FIG. 5 is an enlarged sectional view taken along line 5-5 of FIG. 4, and FIG.
It is a -6 line expanded sectional view.

As shown in FIGS. 1 and 2, an electric wheelchair C having a pair of left and right front wheels Wf, Wf, which are steering wheels, and a pair of left and right rear wheels Wr, Wr, which are driving wheels, is provided at the center of the vehicle body. A battery storage unit 12 and a power unit storage unit 13 are provided at the front and rear of a step floor 11 provided in the vehicle, respectively. The battery storage unit 12 stores running batteries 14, 14, and the front wheels Wf, Wf are stored in the battery storage unit 12. A loop-shaped steering handle 15 for steering is supported, and a seat 16 on which a driver sits is stored in the power unit storage portion 13.
And a power unit 17 for driving the rear wheels Wr, Wr is housed. The power unit 17 includes a motor 18 driven by the batteries 14 and a transmission 19 for transmitting the driving force of the motor 18 to the rear wheels Wr.

The main control panel 20 provided at the center of the steering handle 15 is provided with a power switch 21, a forward / reverse switch 22 and a speed control 23, and an accelerator lever 24 on the right side of the main control panel 20. Is provided.

The power switch 21 can select a "stop" position or an "operation" position. When the "stop" position is selected, the motor drive circuit connecting the batteries 14, 14 and the motor 18 is cut off, and the "operation""
When a position is selected, the motor drive circuit is connected, and the electric wheelchair C is ready to run. The forward / reverse changeover switch 22 can select a “forward” position or a “reverse” position. When the “forward” position is selected, the electric wheelchair C moves forward, and when the “reverse” position is selected, the electric wheelchair C is switched. Drives backward. The speed volume 23 sets the maximum speed of the electric wheelchair C. When the accelerator lever 24 is operated, the traveling speed of the electric wheelchair C changes within the range of the maximum speed set by the speed volume 23.

The steering handle 15 is provided with a brake lever 25 operated by a driver. The brake lever is connected to a drum brake 46 (see FIG. 3) provided inside the transmission 19 via a Bowden cable 26. Connected.

Next, the structure of the power unit 17 will be described with reference to FIGS.

The power unit 17 comprises a motor 18 and a transmission 19. The transmission 19 includes a right casing 31 connected to the left side of the motor 18, a central casing 32 connected to the left side of the right casing 31, And a left casing 33 coupled to a left side surface of the central casing 32. An output shaft 35 of the motor 18 which is projected into the right casing 31 and supported by a ball bearing 34 can be braked by an electromagnetic brake 36 provided at an intermediate portion thereof. The electromagnetic brake 36 functioning as a parking brake device is
When the accelerator lever 24 is in the fully closed position, it is turned on to brake the output shaft 35 of the motor 18, and when the accelerator lever 24 is in a position other than fully closed, the output shaft 35 is released to cancel braking of the output shaft 35 of the motor 18. I do.

Right casing 31 and central casing 3
2 has a reduction shaft 39 via ball bearings 37 and 38.
The first shaft formed at the tip of the output shaft 35 of the motor 18 and meshing with the pinion 40 is
A reduction gear 41 and a second reduction gear 45 meshing with a final gear 44 provided in a differential case 43 of the differential gear 42 are provided. The first reduction gear 41 is rotatably supported by the reduction shaft 39, and the second reduction gear 45 is spline-engaged with the reduction shaft 39 slidably in the axial direction, and is dog-coupled to the first reduction gear 41. To the right by a spring 62. A fork 63 operated by a clutch lever (not shown) is engaged with the second reduction gear 45. When the clutch lever drives the fork 63 to slide the second reduction gear 45 to the left, the second reduction gear The dog connection between the gear 45 and the first reduction gear 41 is released. In this state, the first reduction gear 41 slips with respect to the reduction shaft 39, and the rotation of the rear wheels Wr, Wr is not reversely transmitted to the motor 18, so that the electric wheelchair C can be pushed and moved by human power.

A drum brake 46 functioning as a service brake device or a parking brake device is provided at the left end of the reduction shaft 39 protruding from the central casing 32 to the outside.
Is provided. The drum brake 46 includes a brake drum 47 fixed to a reduction shaft 39, a pair of brake shoes 48 disposed inside the brake drum 47 so as to be openable and closable,
48, a cam shaft 49 which is supported on the brake cover 50 has a cam 49 ₁ to be expanded brake shoe 48 into contact with the inner peripheral surface of the brake drum 47, projecting from the brake cover 50 to the outside And a brake arm 51 fixed to the cam shaft 49. This brake arm 51
Is connected via a Bowden cable 26 to a brake lever 25 provided on the steering handle 15.

Therefore, by operating the brake lever 25 while the electric wheelchair C is running, the Bowden cable 2
6. The brake shoes 48, 48 are expanded via the brake arm 51 and the cam shaft 49 to generate a frictional force between the brake shoes and the brake drum 47, and the drum brake 46 is operated to brake the rear wheels Wr, Wr. be able to. By operating and locking the brake lever 25 to the braking position while the electric wheelchair C is stopped, the drum brake 46 can be held in the operating state and function as a parking brake device.

The differential case 43 and the final gear 44 integral therewith are supported by the right casing 31 and the central casing 32 via ball bearings 52 and 53, respectively. A pair of differential pinions 55, 55 are rotatably supported by a pinion shaft 54 fixed inside the differential case 43, and a right casing 31 and a left casing 33 are provided.
Differential side gears 60, 61 meshing with the pair of differential pinions 55, 55 are provided at opposite ends of left and right axle shafts 58, 59 supported via ball bearings 56, 57, respectively.

Next, the structure of the differential lock device 71 for limiting the differential function of the differential gear 42 will be described with reference to FIG. In FIG. 4, the operation state of the differential lock device 71 is shown below the left axle shaft 59, and the differential lock device 71 is shown above the left axle shaft 59.
Is shown inactive.

The differential lock device 71 includes a final gear 4 integrated with the differential case 43.
4 is coupled to a left axle shaft 59 integral with the left differential side gear 61 to limit the differential function. The connection between the final gear 44 and the left axle shaft 59 is performed via a lock gear 72 spline-connected to the outer periphery of the left axle shaft 59 so as to be slidable in the axial direction. As is clear from FIG. 5, the first dog 72 ₁ ... And the second dog 44 are respectively provided on the outer peripheral surface of the lock gear 72 and the inner peripheral surface of the final gear 44.
₁ ... are formed, the first dog 72 ₁ ... is final gear 44 of the lock gear 72 by the lock gear 72 is moved to the right
Meshes with the second dogs 44 ₁ .
And the left axle shaft 59 are coupled via the lock gear 72 to be in a differential limited state.

An electromagnetic clutch 73 for operating the differential lock device 71 includes an annular electromagnet 75 supported by an electromagnet housing 74 fixed to the left casing 33.
The left axle shaft 59 passes through the center of the electromagnet 75. The idling bush 76 is fitted on the outer periphery of the left axle shaft 59 and is positioned in the axial direction, and the right side surface of the idling bush 76 and the left side surface of the lock gear 72 face each other so as to be in contact with each other. A friction plate 77 is arranged between the right side surface of the electromagnet housing 74 and the left side surface of the idling bush 76. The electromagnet housing 74 is the left casing 33
In contrast, the idling bush 76 rotates while being supported by the left axle shaft 59. Therefore, the friction plate 77 sandwiched between the electromagnet housing 74 and the idling bush 76 is fixed to the electromagnet housing 74 and the idling bush 7.
6 has a slight gap.

A cam member 78 is supported on the outer periphery of the lock gear 72 so as to be relatively rotatable and non-slidable in the axial direction. The left end portion of the cam member 78 and the outer peripheral portion of the friction plate 77 engage with the concave and convex engagement 79 so as to be relatively non-rotatable and axially slidable. As is apparent from FIG. 6 as well, a movable cam 72 having circumferentially continuous peaks and valleys is provided on the right side surface of the lock gear 72.
₂ is formed, on the left side surface of the cam member 78 fixed cam 78 ₁ peaks and valleys are continuous in the circumferential direction is formed.
The movable cam 72 ₂ and the fixed cam 78 ₁ have the same pitch, it is engageable with each other. The lock gear 72 is urged rightward by a spring 80 contracted between the lock gear 72 and the idling bush 76. The spring 80 is housed between the inner peripheral surface of the lock gear 72 and the inner peripheral surface of the idling bush 76 and the outer peripheral surface of the left axle shaft 59 in order to avoid an increase in the size of the electromagnetic clutch 73.

As shown in FIG. 3, an electronic control unit U having a microcomputer includes an accelerator lever 24
Accelerator opening detecting means 81 for detecting the accelerator opening commanded by the accelerator pedal is connected. The electronic control unit U
The operation of the motor 18, the electromagnetic brake 36, and the electromagnetic clutch 73 is controlled based on the accelerator opening detected by the accelerator opening detector 81. Next, the operation of the embodiment of the present invention having the above configuration will be described. Accelerator lever 2
When the electric wheelchair C is running at a position other than the fully closed position, the electromagnetic brake 36 is in an OFF state by a command from the electronic control unit U, and the braking of the output shaft 35 of the motor 18 is released. . 4, the electromagnet 75 of the electromagnetic clutch 73 of the differential lock device 71 is excited, the friction plate 77 is attracted and restrained by the electromagnet 75, and the lock gear 72 is also attracted by the electromagnet 75. It moves leftward against the resilience of the spring 80, and its left side is in contact with the right side of the idling bush 76. In this state, the first dog 72 ₁ of the lock gear 72 that has moved left
Are separated from the second dogs 44 ₁ ... Of the final gear 44, the connection between the differential case 43 and the left axle shaft 59 is released, and the differential gear 42 can exhibit a differential function. At this time,
The fixed cam 78 _first movable cam 72 ₂ and the cam member 78 of the lock gear 72 is moved away (refer to FIG. 6 (A)), the lock gear 72 and idle bush 76 rotates integrally with the left axle shaft 59, the electromagnet 75 The friction plate 77 sucked to the cam member 78 and the cam member 78 that is dog-coupled to the friction plate 77 stop.

While the electric wheelchair C is running,
The rotation of the output shaft 35 of the motor 18 is controlled by the first reduction gear 41, the second reduction gear 45, the final gear 44, the differential gear 42, and the left and right axle shafts 58, 59.
To the left and right rear wheels Wr, Wr. When the electric wheelchair C turns, the differential gear 42 performs a differential function, and the left and right rear wheels Wr, Wr
To enable smooth turning.

When the accelerator lever 24 is operated to the fully closed position, the electromagnetic brake 36 is turned on, and the output shaft 35 of the motor 18 is turned on.
Is braked, and the electric wheelchair C stops. The electronic control unit U controls the electric wheelchair C based on the operation of the electromagnetic brake 36.
Is stopped, and the electromagnet 75 of the electromagnetic clutch 73 of the differential lock device 71 is demagnetized at the same timing. As a result, the lock gear 72 previously attracted by the electromagnet 75 is released and the spring 80
Moved to the right in the elastic force, as shown in the lower part of FIG. 4, a second first dog 72 ₁ ... it is final gear 44 of the lock gear 72
The dogs 44 ₁ engage with each other. Also the rightward movement of the lock gear 72, the movable cam 72 _{and second} lock gear 72 the cam member 78
Engages in the fixed cam 78 ₁ (see FIG. 6 (B)).

As described above, the first dog 7 of the lock gear 72
The 2 ₁ ... and the second dog 44 ₁ ... and mesh with the final gear 44, the lock gear 72 integral with the left axle shaft 59, a final gear 44 integral with the differential case 43 are integrated, the differential gear 42 is the difference Locked immovably.

Thus, even if the rear wheels Wr, Wr try to rotate due to an external force applied while the electric wheelchair C is stopped, the rear wheels Wr
Since the electromagnetic brake 36 (or the drum brake 46) disposed on the path where the driving force is reversely transmitted from the r and Wr to the motor 18 is ON, the rear wheels Wr and Wr are restrained from rotating and the parking brake function is provided. Is exhibited. Even if the rear wheels Wr, Wr are non-rotatably restrained by the electromagnetic brake 36 in this way, if one of the left and right rear wheels Wr is lifted up and floated, the other left and right rear wheels Wr in the ground contact state will be differential geared. In this embodiment, since the differential function of the differential gear 42 is limited by the differential lock device 71, the rotation of the left and right rear wheels Wr in the grounded state is turned on. To the electromagnetic brake 36 to restrict the parking brake function.

When the accelerator lever 24 is operated from the fully closed position in order to run the electric wheelchair C, the electromagnetic brake 36
Is turned off, the motor 18 rotates, and the driving force is transmitted to the left and right rear wheels Wr, Wr. The electronic control unit U detects the start of running of the electric wheelchair C based on the fact that the electromagnetic brake 36 has been turned off, and detects the electromagnet 75 of the electromagnetic clutch 73.
To excite. However, the lock gear 72 and the electromagnet 7
5, the lock gear 72 cannot be moved leftward against the resilience of the spring 80 by the attraction force of the electromagnet 75, and the electromagnet 75 moves the friction plate 77 in the initial stage after the excitation. Only the function of adsorbing to the electromagnet housing 74 and restraining it from rotating is exerted.

When the friction plate 77 is attracted by the electromagnet 75 and its rotation is restricted, the cam member 78 engaged with the concave and convex engagement 79 with this friction plate 77 also cannot rotate. Therefore, the electric wheelchair C
When the left axle shaft 59 rotates with the start of
As shown in FIG. 6 (C), since the relative rotation indicated by the arrow r between the cam member 78 rotates and the left axle shaft 59 integral with the lock gear 72 is generated, the movable cam 72 and _second lock gear 72 is a cam receiving a thrust force shown fixed cam 78 _first member 78 in the arrow f, the lock gear 72 in the thrust force f is moved leftward against the resilient force of the spring 80. As a result, as shown in the upper part of FIG.
The magnet 2 receives a strong attractive force by approaching the electromagnet 75, and is attracted and held at a position in contact with the idle bush 76 by the attractive force. In this state, as shown in FIG. 6 (A), fixed cam 78 of the movable cam 72 ₂ and the cam member 78 of the lock gear 72
Departure from ₁ again.

As described above, by controlling the electromagnetic clutch 73 by the electronic control unit U, the differential lock device 71 automatically operates when the electric wheelchair C is stopped, and also starts when the electric wheelchair C starts running. Since the differential lock device 71 is automatically released, no special operation is required, and the operability is improved. Moreover, the structure can be simplified as compared with the case where a hydraulic clutch is employed, and the reliability is improved.

The first dog 72 of the lock gear 72
₁ ... To second disengaged or engaged with the dog 44 ₁ ... of the final gear 44 of the case 1, the second dog 7
It is necessary to slide the lock gear 72 with a stroke exceeding the height of 2 _1, ..., 44 _{1. In} order to ensure the operation of the differential lock device 71, the lock gear 72 is engaged with the final gear 44. It is necessary to set the elastic force of the spring 80 biased in the direction to be strong. As described above, when the required stroke of the lock gear 72 is large and the spring 80 has a strong elasticity, the electromagnet 75 of the electromagnetic clutch 73 for releasing the operation of the differential lock device 71 needs to be increased in size. This is disadvantageous in securing a space for accommodating 75 and saving power consumption.

However, the electromagnetic clutch 7 of this embodiment
According to 3, without directly sucking the lock gear 72,
The friction plate 77 by suction only to restrain the rotation of the cam member 78 drives the lock gear 72 in the thrust force f (see FIG. 6 (C)) generated by the relative rotation of the fixed cam 78 ₁ and the movable cam 72 ₂ , Can be easily attracted to the electromagnet 75. Thus, while reducing the space and power consumption by reducing the size of the electromagnet 75, the lock gear 72 can be made to largely stroke against the resilience of the spring 80 and the electromagnetic clutch 73 can be reliably engaged.

Next, a second embodiment of the present invention will be described with reference to FIG. The electromagnetic clutch 101 of the second embodiment controls the transmission and release of the driving force from the transmission of the farm equipment to the PTO shaft. The electromagnetic clutch 73 of the first embodiment is disengaged by the excitation of the electromagnet 75. On the other hand, the electromagnetic clutch 101 of the second embodiment is adapted to be engaged by excitation of the electromagnet 75. In the second embodiment, components corresponding to those of the first embodiment are denoted by the same reference numerals as in the first embodiment.

The ball bearing 10 is mounted on the casing 102.
A driving force is input to a pulley 105 provided at one end of the input shaft 104 supported via the endless belt 3 via an endless belt (not shown). An output shaft 107 is coaxially supported at the other end of the input shaft 104 via ball bearings 106,106. The spring 8 is engaged with the input shaft 104 by spline engagement.
The lock gear 72 urged to the left at 0 is the output shaft 10
7 are provided with first dogs 72 ₁ that can be engaged with the second dogs 107 ₁ . The cam member 78 arranged on the outer periphery of the lock gear 72 has a fixed cam 78 ₁ on the right side surface,
This fixed cam 78 ₁ engaging a movable cam 72 ₂ are formed on the left side surface of the lock gear 72.

An electromagnet 75 is supported by an electromagnet housing 74 fixed to the casing 102, and a friction plate 77 is disposed on the left side of the electromagnet 75. The friction plate 77 and the cam member 78 engage with each other so that they cannot rotate relative to each other and can slide in the axial direction. An idling bush 76 supported on the outer periphery of the input shaft 104 is arranged between the friction plate 77 and the lock gear 72, and a gap is formed between the friction plate 77 and the idling bush 76 so that the two can rotate relative to each other.

As shown in the upper part of FIG. 7, when the electromagnet 75 is demagnetized, the lock gear 72 moves leftward due to the elastic force of the spring 80, so that the first dog 72 ₁ . The engagement of the electromagnetic clutch 101 is released by separating from the second dogs 107 ₁ . At this time, the movable cam 72 _{and second} lock gear 72 which is moved to the left engages the fixed cam 78 ₁ of the cam member 78, the lock gear 72, the cam member 78 and the friction plate 77 is rotated together with the input shaft 104.

When the electromagnet 75 is excited from this state, the friction plate 77 is attracted to the electromagnet 75,
Is restricted. Moving a result, as shown in the lower part of FIG. 7, the lock gear 72 rotates relative to the cam member 78 and moved to the right by a reaction force which the movable cam 72 ₂ receives from the stationary cam 78 ₁ toward the electromagnet 75 Then, it is attracted to the electromagnet 75 via the idling bush 76. The right dog of the lock gear 72 causes the first dogs 72 ₁ ... Of the lock gear 72 to move to the second dog 10 of the output shaft 107.
7 ₁ ... to engage, the electromagnetic clutch 101 is engaged.

[0045] Also with this embodiment, only by suction friction plate 77 without sucking the lock gear 72 directly to restrain rotation of the cam member 78, the stationary cam 78 ₁ and the movable cam 72
_The lock gear 72 can be driven in the direction approaching the electromagnet 75 by the thrust force due to the relative rotation of ₂ to be attracted to the electromagnet 75. As a result, while reducing the space and power consumption by reducing the size of the electromagnet 75,
2, the electromagnetic clutch 101 can be reliably engaged by making a large stroke against the elastic force of the spring 80.

Although the embodiments of the present invention have been described in detail, various design changes can be made in the present invention without departing from the gist thereof.

For example, the electromagnetic clutch of the present invention can be applied to any use other than the electric wheelchair C and agricultural equipment.

[0048]

As described above, according to the first aspect of the present invention, when the electromagnet is demagnetized, the meshing engaging member slidably supported by the shaft member slides in the engaging direction by the elastic force of the spring. To transmit the driving force. When the electromagnet is excited, the friction plate is non-rotatably attracted to the electromagnet, and the cam member connected to the friction plate so as to be relatively non-rotatable and slidable in the axial direction is constrained non-rotatably. Relative rotation occurs between the engagement member and the cam member. As a result, the movable cam of the engagement member receives a reaction force from the fixed cam of the cam member, and the engagement member slides in the non-engagement direction against the elastic force of the spring and is attracted to the electromagnet. You. Just by attracting the friction plate with the electromagnet like this,
The movable cam slides the engagement member in the non-engagement direction by the reaction force received from the fixed cam, and can be brought closer to the electromagnet to be surely attracted. Therefore, even if the spring force of the spring is set to be large so as to enable the reliable engagement of the meshing engagement member, the meshing engagement member is reliably slid in the non-engaging direction by the small and low power consumption electromagnet. Can be done.

According to the second aspect of the present invention,
When the electromagnet is excited, the meshing engagement member does not directly contact the friction plate but rotates integrally with the shaft member and is held in contact with the idle bush having a gap between the friction plate and the electromagnet. It is possible to prevent the friction plate, which is attracted to the rotation member and whose rotation is restricted, from directly contacting and sliding with the meshing engagement member rotating integrally with the shaft member.

According to the invention described in claim 3,
Since the spring is housed between the inner peripheral surface of the meshing engagement member and the idling bush and the outer peripheral surface of the shaft member, the electromagnetic clutch can be downsized by disposing the spring compactly.

According to the fourth aspect of the present invention,
When the electromagnet is demagnetized, the meshing engagement member slidably supported by the shaft member slides in the non-engagement direction by the spring force of the spring, thereby interrupting the transmission of the driving force. When the electromagnet is excited, the friction plate is non-rotatably attracted to the electromagnet, and the cam member connected to the friction plate so as to be relatively non-rotatable and slidable in the axial direction is constrained non-rotatably. Relative rotation occurs between the engagement member and the cam member. As a result, the movable cam of the engagement member receives a reaction force from the fixed cam of the cam member, and the engagement member slides in the engagement direction against the elastic force of the spring and is attracted to the electromagnet. . In this manner, only by attracting the friction plate with the electromagnet, the movable cam can be slid in the engagement direction by the reaction force received from the fixed cam, and can be made to approach the electromagnet and be surely attracted. Therefore, even if the spring force of the spring is set to be large in order to surely release the engagement of the meshing engagement member, the meshing engagement member is reliably slid in the engagement direction by the small and low power consumption electromagnet. be able to.

[Brief description of the drawings]

FIG. 1 is an overall side view of an electric wheelchair provided with an electromagnetic clutch according to a first embodiment.

FIG. 2 is a view in the direction of arrows in FIG. 1;

FIG. 3 is an enlarged sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is an enlarged view of a main part of FIG. 3;

FIG. 5 is an enlarged sectional view taken along line 5-5 of FIG. 4;

FIG. 6 is an enlarged sectional view taken along line 6-6 in FIG. 4;

FIG. 7 is a longitudinal sectional view of an electromagnetic clutch according to a second embodiment.

[Description of Signs] 59 Left axle shaft (shaft member) 72 Lock gear (engaging member) 72 ₂ Movable cam 75 Electromagnet 76 Idling bush 77 Friction plate 78 Cam member 78 ₁ Fixed cam 80 Spring 104 Input shaft (shaft member)

Claims (4)

[Claims] An engaging member (72) supported on the outer periphery of a shaft member (59) so as to be slidable in the axial direction, and the engaging member (72) is slid in the engaging direction to reduce the driving force. A spring (80) that enables transmission and an electromagnet (7) that blocks transmission of driving force by sliding the meshing engagement member (72) in the non-engagement direction against the resilience of the spring (80).
And a movable cam (7) formed rotatably on the outer periphery of the meshing engagement member (72) and formed on the meshing engagement member (72).
2 ₂₎ a cam member (78) having engageable with the fixed cam (78 _1), a is disposed so as to face to the electromagnet (75), the cam member (78) to rotate relative and can axially slide And the friction plate (77) is non-rotatably attracted by excitation of the electromagnet (75) and the cam member (78) is non-rotatably restrained by excitation of the electromagnet (75). 72 ₂ ) is the cam member (7
8) With the reaction force received from the fixed cam (78 ₁ ), the meshing engagement member (72) is slid in the non-engagement direction against the elastic force of the spring (80) to be attracted to the electromagnet (75). An electromagnetic clutch, wherein 2. An idle bush (76) which rotates integrally with the shaft member (59) with a gap between the friction plate (77) and the friction plate (77) and the meshing engagement member (72). 2. The electromagnetic clutch according to claim 1, wherein the engagement engaging member (72) attracted by the electromagnet (75) is held by the idling bush (76). 3. A spring (80) is housed between the inner peripheral surface of the meshing engagement member (72) and the idling bush (76) and the outer peripheral surface of the shaft member (59).
The electromagnetic clutch according to claim 2. 4. An engaging member (72) slidably supported on the outer periphery of the shaft member (104) in an axial direction, and a driving force by sliding the engaging member (72) in a non-engaging direction. And an electromagnet (7) that slides the meshing engagement member (72) in the engagement direction against the elastic force of the spring (80) to enable transmission of the driving force.
And a movable cam (7) formed rotatably on the outer periphery of the meshing engagement member (72) and formed on the meshing engagement member (72).
2 ₂₎ a cam member (78) having engageable with the fixed cam (78 _1), a is disposed so as to face to the electromagnet (75), the cam member (78) to rotate relative and can axially slide And the friction plate (77) is non-rotatably attracted by excitation of the electromagnet (75) and the cam member (78) is non-rotatably restrained by excitation of the electromagnet (75). 72 ₂ ) is the cam member (7
8) With the reaction force received from the fixed cam (78 ₁ ), the meshing engagement member (72) is slid in the engagement direction against the elastic force of the spring (80) to be attracted to the electromagnet (75). An electromagnetic clutch, characterized in that: