JPH0377392B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a scroll type oil-free vacuum pump that is directly connected to a motor among scroll type fluid machines.

[Prior art] Among scroll-type fluid machines, oil-free vacuum pumps that are directly connected to motors have not yet been developed. No matter what is used, some form of sealing device is provided on the rotating shaft portion leading to the atmosphere or the motor side.

[Problem that the invention seeks to solve]

Generally, the engagement distance of the scroll wrap must be kept to a minimum to improve performance.

However, it is necessary to assemble this part with a slight delay in view of the expansion allowance when the temperature rises due to gas compression. In addition, in the case of an oil-free type, frictional heat is generated by the thrust load of the orbiting scroll in the parts that receive the load, bearings, and other contact rotating parts, and furthermore, the rotating shaft is isolated from the atmosphere or the motor side. A particularly large amount of frictional heat is generated in the sealing device section provided in the sealing device. The frictional heat generated by this shaft sealing device is directly transmitted through the rotating shaft to the crankshaft portion, where it is transmitted to the orbiting scroll through the bearing of the crankshaft portion. Therefore,
When assembling the scroll wrap engaging portion, a considerable amount of clearance must be provided. Therefore, for a certain period of time at the beginning of startup, that is, until the temperature rises to a predetermined temperature, the lap interval is too large and the predetermined pressure cannot be reached due to leakage from that part. . Further, the friction loss at the shaft seal portion greatly affects the driving force, leading to a decrease in the efficiency of the pump. Furthermore, if an oil seal is used as the sealing device, there is no reliability in shutting off, and if a mechanical seal is used, it is difficult to achieve oil-free operation.

[Means for solving problems]

In a scroll consisting of a fixed scroll, an orbiting scroll, a rotating shaft with a crankshaft, a casing, and a motor, the fixed scroll is formed integrally with a first casing, and the second and third casings are successively connected to the first casing. A scroll wrap engaging part is housed in the second casing, a motor whose rotating shaft also serves as a rotating shaft with a crankshaft is housed in the third casing, and the suction chamber formed in the first casing has an orbiting scroll. It communicates with the motor room through the back space, eliminating the need for a shaft seal device and making it oil-free.

[Effect]

When used as a vacuum pump, when the motor is started, the degree of vacuum on the suction chamber side increases, and the degree of vacuum in the back space of the orbiting scroll communicating with this also increases, and furthermore, the degree of vacuum in the motor chamber, which communicates with this, becomes almost the same.

In this case, since there is no shaft seal device on the rotating shaft with crankshaft that also serves as the motor shaft, there is no friction due to the seal device, so not only is there no power loss due to this, but there is also no generation of frictional heat.
It can be easily made oil-free.

Therefore, since there is no risk of temperature rise due to the sealing device at the scroll wrap engaging part from the time of assembly, the thermal expansion allowance can be kept small, so even immediately after startup, there is no risk of temperature rise due to the sealing device. No leakage will occur.

〔Example〕

To explain the embodiment shown in the drawings, 1 is the first
It is a fixed scroll integrally formed with a casing, and has a lap 1a facing downward and is connected to a second casing 2 on its lower surface, and the second casing 2 is further connected to a third casing 3 on its lower surface.

4 is a rotating shaft with a crankshaft that also serves as a motor rotating shaft; the upper part is supported by a bearing 5 against the second casing 2; the lower part is supported by a bearing 7 against a lower cover 6 provided at the lower end of the third casing 3; A crankshaft 4a is integrally formed with a predetermined eccentricity.

Reference numeral 8 denotes an orbiting scroll, which is fitted onto the crankshaft 4a via an orbiting bearing 9, with its lap 8a meshing with the lap 1a of the fixed scroll, and its end plate has a wear-resistant structure between it and the upper wall of the second casing 2. A thrust bearing 10 made of a non-lubricated sliding material is provided, and an appropriate number of pin cranks 11 similarly provided between the upper wall of the second casing 2 are used to automatically prevent the rotation of the rotating shaft 4. It is designed to do the following.

Reference numeral 12 denotes a vacuum motor fitted in the third casing 3, and the motor shaft is also used as the rotating shaft 4 with a crankshaft as described above.

The fixed scroll 1, the second casing 2, and the third casing 3 are provided with water jackets 1b, 2a, and 3a around their respective peripheries to allow them to communicate with each other, and a water passage hole 6a is provided in the lower cover 6 to allow cooling water to flow therethrough. Entrance and none, plus fixed scroll 1
A water passage hole 1c is provided in the housing to serve as a cooling water outlet, and each part can be cooled by circulating cooling water introduced from the outside.

In addition, the bearings 5, 7, 9 and pin crank 11
The bearings, etc. are all slightly coated with low vapor pressure grease. In the figure, 1d is the suction chamber, 1e is the discharge port, 2b is the communication hole, 13 is the back space of the orbiting scroll, 14 is the balance weight, and 15 is the counter. weight,
16 indicates a vacuum motor chamber.

Next, the effect will be explained. When the vacuum motor 12 is started, the rotating shaft 4 with a crankshaft rotates, and in conjunction with this, the orbiting scroll 8 performs an orbiting motion around the rotating shaft 4 . As a result, laps 1a and 8a
engages to sequentially compress the fluid sucked in from the suction chamber 1d, and performs a compression action to discharge it from the discharge port 1e.

In this case, the vacuum degree of the orbiting scroll back space 13 communicating with the suction chamber 1d increases at the same time,
Further, a bearing 5 and a communication hole 2 are provided for the back space 13.
The degree of vacuum of the vacuum motor chamber 16, which is communicated through b, also increases almost at the same time.

Incidentally, since the bearings 5, 7, 9 and the bearings of the pin crank 11 are coated with low vapor pressure grease for vacuum use as described above, the inside of each bearing is also in a vacuum.

Furthermore, at the same time as the motor 12 is started, cooling water circulation is started through the water passage hole 6a, and as a result, the motor section, the shaft section 5 section, the thrust bearing section 10, the engaging section of the laps 1a and 8a, etc., which become hot, are sequentially cooled down. will be carried out.

〔Effect of the invention〕

In the scroll type oil-free vacuum pump according to the present invention, the suction chamber is communicated with the motor chamber through the back space of the orbiting scroll, and no sealing device is provided on the rotating shaft with a crankshaft that also serves as the motor shaft. Therefore, the conventional shaft seal device,
In particular, the heat generation and power loss that occur when a mechanical seal is provided can be minimized, and the number of parts can be reduced to achieve oil-free operation. Furthermore, since the amount of heat transmitted through the shaft is small, there is no need to make the scroll wrap engagement distance very large. As a result, even immediately after the motor is started, the gap between the laps is small, so leakage loss at that part is also small, and an efficient scroll type oil-free vacuum pump can be obtained.

[Brief explanation of drawings]

The drawing is a longitudinal sectional view showing one embodiment of the scroll type oil-free vacuum pump according to the present invention, in which 1 is a fixed scroll, 1a is a wrap, 1d is a suction chamber, 2 is a second casing, and 3 is a third casing. casing,
4 is a rotating shaft with a crankshaft, 8 is an orbiting scroll,
8a is a wrap, 12 is a vacuum motor, 13 is a space behind the orbiting scroll, and 16 is a vacuum motor chamber.

Claims (1)

[Claims] 1 In a scroll consisting of a fixed scroll, an orbiting scroll, a rotating shaft with a crankshaft, a casing, and a motor, the fixed scroll is formed integrally with a first casing, and the second and third casings are successively connected to the first casing. A scroll wrap engaging portion is housed in the first and second casings, and a third
A motor whose rotating shaft also serves as a rotating shaft with a crankshaft is housed in the casing, and the suction chamber formed in the first casing is communicated with the motor chamber through the back space of the orbiting scroll, eliminating any shaft sealing device. A scroll type oil-free vacuum pump featuring the following.