JP2008082388A - Power transmission mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission mechanism capable of cutting off axial force by sliding a member screw face and a bearing face when excessive torque is applied, moving a member in a loosening direction, and idling a power transmission side. <P>SOLUTION: When a shaft 3 continuous with a driven device is irrotational, by using excessive torque exceeding predetermined transmission torque applied to a screw face between a nut 5 and an outer circumference part of the shaft 3 and a contact face between a spacer 6 and the shaft 3, the nut 5 is slid in the loosening direction, the outer circumference part of the shaft 3 is moved, and rotary power from a pulley 2 is cut off. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power transmission mechanism, and more particularly to a power transmission mechanism that is effective for use in a normally rotating type (electromagnetic clutchless) compressor for a car air conditioner.

Conventionally, as a power transmission mechanism having a torque limiter function, for example, an annular groove is provided in a disk part of a pulley, and through holes are provided at regular intervals in this groove part to reduce the strength of the disk part, thereby transmitting torque. When the torque exceeds a predetermined torque, the groove is broken to interrupt power transmission.
However, in such a configuration, the structure is simple and advantageous in terms of manufacturing cost. However, since it is necessary to determine the size and material of the fractured portion by trial and error, there is a difficulty in design. .
Therefore, a configuration that can cut off power transmission without causing fatigue failure has been proposed as follows.

JP 2003-307265 A

  In the power transmission mechanism in this document, when an excessive torque is applied, the screw surface and the seat surface slide, and the screw is tightened, resulting in an increase in axial force and breaking of the narrow-diameter portion. .

  According to the power transmission mechanism having such a configuration, there is an advantage that it is difficult to be affected by fatigue, but there is a problem that variation in operating torque is large.

By the way, factors determining the operating torque include the friction coefficient of the screw surface, the dimensional accuracy of the narrow diameter portion, and the material strength of the narrow diameter portion. In particular, the material strength of the narrow-diameter portion depends on the manufacturing lot and the manufacturer, and varies widely. As a result, the guaranteed range of the operating torque of the torque limiter must be set as wide as, for example, 50 to 120 Nm. .
The lower limit of the guaranteed operating torque range must be greater than or equal to the maximum torque during normal operation of the compressor, and the upper limit is higher than the torque at which the belt slips and the torque at which the engine stalls from the viewpoints of drive belt protection and engine stall prevention. Small is essential.

However, in recent years, compressors have been reduced in cost, and measures such as reducing the number of pistons have been taken, and fluctuations in drive torque have been increasing. In addition, the drive belt is reducing the tension in order to reduce fuel consumption, and the belt slip torque tends to decrease.
If the guaranteed range of the operating torque is not small, it will not be established as a vehicle. Therefore, it is desired to realize a torque limiter with a small variation.
The present invention has been proposed to improve such a problem, and by breaking the member, the excessive torque is not released, but when the excessive torque is applied, the member screw surface and the seat surface slip, It is an object of the present invention to provide a power transmission mechanism that can idle a power transmission side and block an axial force by moving a member in a loosening direction.

  In order to solve the above-mentioned problems, in claim 1 of the present invention, when the shaft (3) connected to the driven device is not rotatable, it is applied to the screwing surface between the nut (5) and the outer peripheral portion of the shaft (3). An excessive torque exceeding a predetermined transmission torque causes the outer periphery of the shaft (3) to move by sliding the nut (5) in a loosening direction so as to cut off the rotational power from the pulley (2). So, unlike the configuration where the excessive torque was released by breaking the member as before, there is no need to install the replacement part instead of the broken part at the time of recovery. No parts are required.

  In addition, the reference numerals in parentheses attached to each of the above means and each means described below are an example showing a correspondence relationship with specific means described in the embodiment described later.

  According to a second aspect of the present invention, the hub (4) includes a spacer (6) in contact with the shaft (3) near the driven device, and the shaft (3) connected to the driven device rotates. Excessive torque exceeding the predetermined transmission torque applied to the screwed surface between the nut (5) and the outer periphery of the shaft (3) and the contact surface between the spacer (6) and the shaft (3). Thus, the outer peripheral portion of the shaft (3) is moved by sliding the nut (5) in the loosening direction, and the rotational power from the pulley (2) is cut off. Therefore, the pulley (2) To the shaft (3) can be cut off.

  In the third and fourth aspects of the present invention, the tip end of the shaft (3) and the adapter (10) are configured as a spline coupling portion (Sp) or a serration coupling portion (Sr), while the adapter (10) has an outer periphery. Is screwed into the nut (5), and the nut (5) and the hub (4) are connected to each other so that they can be connected dynamically and disconnected from the pulley (2). The rotational power of the shaft (3) can be transmitted to the shaft (3) within a predetermined transmission torque, and the bolt (11) and the adapter (10) are brought into contact with each other. ) The contact surface between the bolt (11) on the tip side and the adapter (10) starts to slide, and the nut (5) rotates together with the pulley (2) and the hub (4). As a result, the nut (5) moves on the outer periphery of the adapter (10) in the loosening direction and is detached from the hub-side rotation fitting portion (4b) of the hub (4). can do.

  Further, in the fifth and sixth aspects of the present invention, the nut (5) is provided by providing a drop prevention means (7) for preventing the nut (5) from dropping at the tip of the shaft (1) or the bolt (11). Even if it is loose, it will not fall out.

Hereinafter, an embodiment of the power transmission mechanism according to the present invention will be described and described with reference to the accompanying drawings.
FIG. 1 shows a power transmission mechanism 1 for transmitting power from a power source such as an engine to a compressor P constituting an air conditioner, for example, using a power transmission mechanism according to the present invention. .
That is, the power transmission mechanism 1 transmits a rotational force from a power source to the compressor P via a power transmission member (not shown) such as a belt, and a pulley 2 that spans the power transmission member. And a driven shaft S of the compressor P and a shaft 3 connected so as to extend in the axial direction.
The pulley 2 is provided around the shaft 3 and has a hub 4 integrally formed with the pulley 2 on the inner peripheral side of the pulley 2.

On the other hand, the shaft 3 extending in the axial direction on the driven shaft S of the compressor P has an outer peripheral portion screwed therein, and a nut 5 is screwed therein.
The nut 5 and the hub 4 are each provided with a nut-side detent fitting portion 5b and a hub-side detent fitting portion 4b so that the nut 5 and the hub 4 are fitted in close contact with each other. ing.
In this case, the hub-side detent fitting portion 4b is formed in the hub 4 as a polygonal (for example, hexagonal) concave portion, and the nut-side detent fitting portion 5b is formed on the head flange portion 5f of the nut 5. The outer shape is formed as a hexagonal rectangular tube corresponding to the hub side rotation fitting portion 4b of the hexagonal recess (see FIG. 2).
That is, the nut 5 and the hub 4 are fitted in close contact with each other via the nut-side detent fitting portion 5b and the hub-side detent fitting portion 4b, so that the rotational power from the pulley 2 is obtained. The shaft 3 is transmitted to the driven shaft S of the compressor P.

Further, the hub 4 can be in a state of being in close contact with a spacer 6 made of an appropriate material formed around the coupling portion with the shaft 3 at a portion near the driven shaft S of the compressor P.
The spacer 6 may not be provided.
Further, a drop prevention means 7 for preventing the nut 5 from falling off is provided at the tip of the shaft 3. As the drop-off prevention means 7, a C-type retaining ring can be used as shown in the figure.

The power transmission mechanism 1 according to the present invention is configured as described above, and the operation thereof will be described next.
Now, when the rotational force is transmitted from the engine side via a power transmission member such as a belt stretched around the pulley 2 in the power transmission mechanism 1, this rotational force is transmitted through the hub 4 and the nut 5 inside the pulley 2. The shaft 3 can be transmitted to the driven shaft S of the compressor P constituting the air conditioner, and the air conditioner can be operated. When the compressor P is functioning normally, it can rotate with a predetermined torque, and the power transmission mechanism 1 can transmit the rotational force to the compressor P without any trouble (FIG. 1). reference).

Here, when the compressor P is unable to rotate due to some failure of the compressor P, the rotational force is applied to the pulley 2 from the engine side via the power transmission member even under such a situation. It tries to continue to rotate with the hub 4.
As a result, an excessive torque greater than the normal rotational torque is applied to the screw surface of the shaft 3, the screw surface of the nut 5, and the contact surface between the shaft 3 and the spacer 6 near the driven shaft S of the compressor P. It will be.
Therefore, the screw surface of the shaft 3 and the screw surface of the nut 5 and the contact surface between the shaft 3 and the spacer 6 near the driven shaft S of the compressor P start to slide.
At that time, since the nut 5 is closely fitted to the hub 4 via the nut side rotation fitting portion 5b and the hub side rotation fitting portion 4b, the nut 5 together with the pulley 2 and the hub 4 is fitted. Keeps rotating. As a result, the nut 5 slides on the screw surface of the shaft 3 in the loosening direction, and only the nut 5 gradually moves on the shaft 3 toward the distal end side of the shaft 3, and the nut 5 The nut 5 disengages from the hub side stop fitting portion 4b of the hub 4 and the coupled state with the hub 4 is canceled. As a result, the pulley 2 and the hub 4 are idled, thereby rotating. The power is cut off (see FIG. 3).
Even if the nut 5 moves on the shaft 3 toward the tip side, the tip of the shaft 3 is provided with a C-type retaining ring which is a drop-off preventing means 7, so that the nut 5 is dropped. There is no such thing as to do.
As described above, in the power transmission mechanism 1, the pulley 2 and the hub 4 on the power transmission side and the nut 5 screwed to the shaft 3 on the power reception side are loosened in a direction in which the nut 5 is relatively loosened. Since it was achieved by sliding and shutting off the power coupling state, unlike the configuration in which excessive torque was released by breaking the member as before, it changed to the broken part at the time of restoration, and it was a replacement part There is no need for assembling and no replacement parts are required.

The operating torque at which the screw surface of the shaft 3 and the screw surface of the nut 5 and the contact surface of the shaft 3 near the driven shaft S of the compressor P and the spacer 6 start to slide is only the friction coefficient and the assembly torque. Therefore, the variation in the operating torque can be suppressed.
In other words, the slip of the nut 5, that is, the loosening torque can be measured at the manufacturing stage, so that it is easy to guarantee the operating torque.

The power transmission mechanism 1 according to the present invention can also be configured as follows.
In the power transmission mechanism 1 in this case, the operating torque is determined by a single pulley 2 and the pulley 2 and the hub 4 on the power transmission side are connected to the distal end side of the shaft 3 on the power receiving side with the adapter 10. In this way, the bolts 11 are assembled from the front end side of the shaft 3 (see FIG. 4).
In this case, although the illustration is omitted, the tip end side of the shaft 3 and the adapter 10 are splined and configured as a spline coupling part Sp. The distal end side of the shaft 3 and the adapter 10 may be serrated to form a serration coupling portion Sr.
Then, the nut 10 is screwed onto the outer periphery of the adapter 10. The nut 5 is closely fitted to the hub 4 via the nut side detent fitting portion 5b and the hub side detent fitting portion 4b.

  In such a power transmission mechanism 1, due to excessive torque, the contact surface between the bolt 11 on the distal end side of the shaft 3 and the adapter 10 starts to slide, and the nut 5 rotates together with the pulley 2 and the hub 4. Accordingly, the nut 5 moves on the outer periphery of the adapter 10 in the loosening direction and is detached from the hub-side rotation fitting portion 4b of the hub 4, so that the power can be cut off.

It is an example of the power transmission mechanism concerning this invention, and is sectional explanatory drawing which shows the state in which power transmission is possible. It is principal part explanatory drawing from the A direction of the power transmission mechanism shown in FIG. In the power transmission mechanism shown in FIG. 1, it is sectional explanatory drawing in the state which interrupted | blocked motive power. It is another example of the power transmission mechanism concerning this invention, and is sectional explanatory drawing which shows the state in which power transmission is possible.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power transmission mechanism 2 Pulley 3 Shaft 4 Hub 4b Hub side rotation fitting part 5 Nut 5b Nut side rotation fitting part 5f Flange part 6 Spacer 7 Drop-off prevention means 10 Adapter 11 Bolt P Compressor S Driven shaft Sp Spline Joint Sr Serration joint

Claims (6)

A power transmission mechanism (1) for transmitting rotational power to a shaft (3) connected to the driven device to a driven device via a pulley (2) motively coupled to a power source;
Screw the nut (5) into the outer periphery of the shaft (3),
This nut (5) and the hub (4) located on the inner peripheral side of the pulley (2) are configured to be fitted so as to be able to be connected and disconnected in a power manner, and rotational power from the pulley (2) is predetermined. Configured to transmit to the shaft (3) within the transmission torque of
When the shaft (3) connected to the driven device cannot be rotated, an excessive torque exceeding the predetermined transmission torque applied to the screwing surface between the nut (5) and the outer peripheral portion of the shaft (3) causes the nut ( 5) A power transmission mechanism in which the outer peripheral portion of the shaft (3) is moved by sliding it in a loosening direction to block the rotational power from the pulley (2).   The hub (4) includes a spacer (6) formed in contact with the shaft (3) closer to the driven device, and when the shaft (3) connected to the driven device cannot rotate, the hub (4) The nut (5) is loosened due to an excessive torque exceeding the predetermined transmission torque applied to the screwing surface with the outer peripheral portion of the shaft (3) and the contact surface between the spacer (6) and the shaft (3). The power transmission mechanism according to claim 1, characterized in that the outer peripheral portion of the shaft (3) is moved by sliding in a direction to cut off the rotational power from the pulley (2). A power transmission mechanism (1) for transmitting rotational power to a shaft (3) connected to the driven device to a driven device via a pulley (2) motively coupled to a power source;
The hub (4) located on the inner peripheral side of the pulley (2) is assembled to the distal end side of the shaft (3) with the bolt (11) from the distal end side of the shaft (3) via the adapter (10).
The shaft (3) tip side and the adapter (10) are configured as a spline coupling part (Sp), while the adapter (10) is threaded around the outer periphery and a nut (5) is screwed in
The nut (5) and the hub (4) are connected to each other so that they can be connected and cut off dynamically. The rotational power from the pulley (2) is transmitted within a predetermined transmission torque to the shaft (3). To be able to communicate
Bringing the bolt (11) and the adapter (10) into contact;
When the shaft (3) connected to the driven device cannot be rotated, it is applied to the screwed surface between the outer periphery of the adapter (10) and the nut (5), and the contact surface between the bolt (11) and the adapter (10). A configuration in which the outer periphery of the adapter (10) is moved by sliding the nut (5) in a loosening direction by an excessive torque exceeding the predetermined transmission torque, and the rotational power from the pulley (2) is cut off; A power transmission mechanism characterized by that. A power transmission mechanism (1) for transmitting rotational power to a shaft (3) connected to the driven device to a driven device via a pulley (2) motively coupled to a power source;
The hub (4) located on the inner peripheral side of the pulley (2) is assembled to the distal end side of the shaft (3) with the bolt (11) from the distal end side of the shaft (3) via the adapter (10).
The shaft (3) tip side and the adapter (10) are configured as a serration coupling part (Sr), while the adapter (10) is threaded around the outer periphery, and a nut (5) is screwed in,
The nut (5) and the hub (4) are connected to each other so that they can be connected and cut off dynamically. The rotational power from the pulley (2) is transmitted within a predetermined transmission torque to the shaft (3). To be able to communicate
Bringing the bolt (11) and the adapter (10) into contact;
When the shaft (3) connected to the driven device cannot be rotated, it is applied to the screwed surface between the outer periphery of the adapter (10) and the nut (5), and the contact surface between the bolt (11) and the adapter (10). A configuration in which the outer periphery of the adapter (10) is moved by sliding the nut (5) in a loosening direction by an excessive torque exceeding the predetermined transmission torque, and the rotational power from the pulley (2) is cut off; A power transmission mechanism characterized by that.   3. The power transmission mechanism according to claim 1, wherein a drop-off prevention means for preventing the nut from dropping off is provided at a tip of the shaft.   The power transmission mechanism according to claim 3 or 4, wherein a drop prevention means (7) for preventing the nut (5) from falling off is provided at a tip of the bolt (11).

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