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Compressor

Compressor description/claims

1. Field of the Invention

This invention relates to a compressor having a torque limiter for interrupting a power transmission under an excessively large load.

2. Description of the Related Art

A compressor having a torque limiter is shown in FIG. 6. In a swash plate compressor 11, a drive shaft 19 is journaled between a front housing 15 and a cylinder block 17 defining a control pressure chamber 13, and a pulley 23 is mounted at the forward end portion of the drive shaft 19 through a torque limiter 21. A discal lug plate 25 is fixed to the portion of the drive shaft 19 in the control pressure chamber 13, and a swash plate 27 is arranged in engagement with the lug plate 25. A plurality of pistons 29 are slidably arranged along the outer periphery of the swash plate 27. In this swash plate compressor 11, the rotation of the pulley 23 rotates the drive shaft 19 and the lug plate 25 fixed to the drive shaft 19 through the torque limiter 21. With the rotation of the lug plate 25, the swash plate 27 engaged thereby is rotated. The rotation of the swash plate 27 drives the pistons 29 thereby discharging a fluid.

In this swash plate compressor 11, a lip seal 31 is arranged between the drive shaft 19 and the front housing 15 to prevent leakage of a refrigerant or the like from inside the control pressure chamber 13. In order to supply a lubricating oil to the lip seal 31, a very long center hole 33 is formed from the rear end of the drive shaft 19 to the neighborhood of the lip seal 31.

However, this long center hole 33, is difficult to form due to the liability of the cutter blade to break or the hole to be curved on the one hand and a long period of time required by the drilling process on the other hand, thereby posing the problem of high cost.

The torque limiter 21 is intended to break a thin portion with an increased axial force by retightening the screw under an excessively large torque. With the secular change of the friction coefficient, the torque limiter 21 cannot be operated with an expected torque. In order to stabilize the friction coefficient, therefore, a rust-proofing process is executed by applying grease or otherwise to the screw surface and seat surface. Also, the torque limiter 21, which is mounted outside the compressor, may be exposed to water, which requires rust-proofing. Further, in order to prevent the screw portion from being flooded with water, a rubber cap 35 is required. All these requirements pose the problem of increased cost.

Other examples of the swash plate compressor are described in Japanese Unexamined Patent Publications. Nos. 2003-307265 and 2003-206950.

The object of this invention is to solve these problems and provide a compressor which facilitates the machining of the center hole and eliminates the need of rust-proofing the torque limiter.

In order to achieve this object, according to a first aspect of the invention, there is provided a compressor comprising a shaft (43) passed through the front wall portion of a housing (15), a lip seal (31) arranged on the portion of the shaft (43) passing through the front wall portion, a rotary member (25) arranged on the shaft (43) in the housing (15), compression mechanisms (27, 29) rotated by the rotary member (25), and lubricating oil feeding paths (51, 69) leading from the rear portion of the housing (15) to the lip seal (31) through the shaft (43), wherein the shaft (43) has a front shaft (47) and a rear shaft (45) coupled to each other through a torque limiter (65) with lubricating oil feeding paths (51, 69) in communication with each other, and the rotary member (25) fixed to the rear shaft (45).

According to a second aspect of the invention, there is provided a compressor, wherein the rotary member is a lug plate, and the compression mechanisms are pistons (29) and a swash plate (27) rotated by the lug plate (25).

In these aspects of the invention, the length of the hole formed in the shaft (45, 47) can be shortened, and the process of forming the center hole is facilitated. Also, by using a tubular material for the rear shaft (45), costs can be remarkably reduced. Further, the interposition of the torque limiter (65) between the rear center hole (51) and the front center hole (69) makes it possible to immerse the female screw (53) and the male screw (63) of the torque limiter (65) in the lubricating oil of the refrigerant, thereby eliminating the need for rust-proofing. Also, the torque limiter (65), which is located in the housing (15), is not exposed to water, thereby eliminating the need of a waterproof cap or rust-proofing.

According to a third aspect of the invention, there is provided a compressor, wherein the torque limiter (65) includes a male screw portion (63) formed on the end surface (59) of one of the front shaft (47) and the rear shaft (45) through a small-diameter portion (61) and a female screw portion (53) formed inward of the other one of the front shaft (47) and the rear shaft (45) from the end surface of the other shaft, and wherein the male screw portion (63) and the female screw portion (53) are screwed to each other while the end surface of the one shaft and the end surface of the other shaft are in contact with each other. Thus, the torque limiter can be configured with a simple structure and the cost can be reduced.

According to a fourth aspect of the invention, there is provided a compressor, wherein the one shaft having the male screw portion (63) is the front shaft (47) and the other shaft having the female screw portion (53) is the rear shaft (45). By using a tubular member for the rear shaft (45), the female screw portion (53) can be easily machined.

According to a fifth aspect of the invention, there is provided a compressor, wherein the front and rear parts of the rear shaft (85) are journaled by bearings (73, 57). Even in the case where the screw portion or the seat surface is not precise, decentering is prevented.

According to a sixth aspect of the invention, there is provided a compressor, wherein the front shaft (47) includes a large-diameter portion (75) for preventing the torque limiter (65) from coming off from the front wall of the housing (15) in the case where the torque limiter (65) is activated and separated from the rear shaft (45).

According to a seventh aspect of the invention, there is provided a compressor comprising a shaft (43) having one end portion (77) connected to a power source and the other end portion reaching the interior of a housing (15) through the wall portion of the housing (15), a rotary member (25) arranged on the shaft (43) in the housing (15), and compression mechanisms (27, 29) rotated by the rotary member (25), wherein a torque limiter (65) is arranged on that part of the power transmission path leading from the one end portion (77) of the shaft (43) to the rotary member (25) which is located inside the housing (15).

According to a eighth aspect of the invention, there is provided a compressor, wherein the rotary member is a lug plate (25) and the compression mechanisms (27, 29) are a swash plate (27) and pistons (29) rotated by the lug plate (25). In these configurations, the torque limiter (65) which is located in the front housing (15) is not exposed to moisture, thereby eliminating the need of a waterproof cap and rust-proofing. Also, the torque limiter, being arranged in the housing, is lubricated by the lubricating oil of refrigerant so that a stable working torque can be maintained for a long period of time.

The reference numerals in the parentheses attached to the respective means represent an example of correspondence with specific means described in the embodiments later.

The present invention may be more fully understood from the description of preferred embodiments of the invention, as set forth below, together with the accompanying drawings.

• Provisional Patent
• Utility Patent

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