Transmission and compressor or vacuum pump provided with such a transmission

Abstract

Transmission between drive shaft and a driven shaft, which transmission includes a housing and at least a driven gearwheel that is mounted on the driven shaft and a drive gearwheel that is mounted on a drive shaft. The housing is provided with an outlet opening, which outlet opening is placed in the radial extension of one of the gearwheels.

Claims

1. A transmission between a drive shaft and a driven shaft, which transmission comprises: a housing and at least a driven gearwheel that is mounted on the driven shaft and a drive gearwheel that is mounted on a drive shaft, wherein the housing is provided with an outlet opening, and the outlet opening connects to a discharge pipe; wherein the outlet opening is placed in an extension of a radial of one of the gearwheels passing through a rotational axis of the one of the gearwheels or in an extension of a gearwind of the one of the gearwheels, and the discharge pipe extends from the outlet opening at an angle offset from the radial in a direction of the extension of the gearwind; whereby the outlet opening is configured for removing an oil-air mixture present in the housing from the housing, wherein oil of the oil-air mixture is injected in the housing and air from the oil-air mixture is leakage flow originating from a compressor or a vacuum pump element.

2. The transmission according to claim 1, wherein the outlet opening is placed in the radial extension of a biggest gearwheel.

3. A compressor provided with a compressor element and a motor to drive the compressor element, wherein the compressor is provided with a transmission according to claim 1 between the drive shaft of the motor and the driven shaft of the compressor element.

4. A vacuum pump provided with a vacuum pump element and a motor to drive the vacuum pump element, wherein the vacuum pump is provided with a transmission according to claim 1 between the drive shaft of the motor and the driven shaft of the vacuum pump element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) With the intention of better showing the characteristics of the invention, a few preferred embodiments of a transmission according to the invention and a compressor or vacuum pump equipped with such transmission are described hereinafter by way of an example, without any limiting nature, with reference to the accompanying drawings, wherein:

(2) FIG. 1 schematically shows a transmission according to the invention;

(3) FIG. 2 schematically shows a view according to the cross-section X-X of FIG. 1;

(4) FIG. 3 schematically shows an alternative embodiment of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

(5) The compressor 1 shown in FIG. 1 essentially comprises a compressor element 2, a motor 3 and a transmission 4 between the compressor element 2 and the motor 3.

(6) The compressor element 2 is in this case a screw compressor element 2, which comprises a compressor element housing 5 and two co-operating screw rotors 6a, 6b, more specifically a male screw rotor 6a and a female screw rotor 6b, the lobes 7 of which turn into each other co-operatively.

(7) Both rotors 6a, 6b are mounted with bearings by means of their shaft 8 in the compressor element housing 5.

(8) The shaft 8 of one of the rotors 6b is extended and forms the driven shaft 9.

(9) This driven shaft 9 reaches into the housing 10 of the transmission 4, and the driven gearwheel 11 is mounted at the end of it.

(10) In order to close off the compressor element 2 from the transmission 4, two seals 12a, 12b are mounted on the driven shaft 9: an oil seal 12a and an air seal 12b.

(11) The motor 3 has a drive shaft 13 that reaches into the housing 10 of the transmission 4 and on which a drive gearwheel 14 is mounted that engages on said driven gearwheel 11.

(12) The transmission 4 comprises the aforementioned housing 10 with said gearwheels 11 and 14 therein.

(13) Of course, it is not excluded that in the housing 10 additional gearwheels are mounted between the driven gearwheel 11 and the drive gearwheel 14.

(14) Nor does this exclude that the motor 3 is located in the housing 10 of the transmission 4.

(15) Furthermore, the transmission 4 is provided with an oil reservoir 15 and a filter element 16 connected to it, to be able to filter the oil out of the oil-air mixture which is ventilated via the oil reservoir 15 and filter element 16 into the atmosphere.

(16) The injected oil is collected in the oil reservoir 15.

(17) Furthermore, the compressor 1 in the shown example is also provided with an oil circuit 17, which can return the oil collected in the oil reservoir 15, i.e. the oil that flows back out of the housing 10 and the oil separated by the filter element 16, with an oil pump 18 back to the transmission 4 and/or the motor 3. Additionally, the oil circuit 17 is also provided with an oil filter 19 to be able to remove impurities from the oil.

(18) According to the invention, the housing 10 of the transmission 4 is provided with an outlet opening 20, which is placed in the radial extension of the biggest gearwheel 14.

(19) As aforementioned, this means that the outlet opening 20 extends according to a radial direction X-X of the gearwheel 14. This means according to a direction X-X of a line that extends from the centre 21 of the biggest gearwheel 14.

(20) In this case the drive gearwheel 14 is the biggest gearwheel.

(21) It is not necessary for the invention that the outlet opening 20 extends according to a radial direction of the biggest gearwheel, i.e. in this case the drive gearwheel 14. It is also possible that the outlet opening 20 extends according to a radial direction of a smaller gearwheel, in this case the driven gearwheel 11.

(22) In the shown example, the cutlet opening 20 is also placed under the drive gearwheel 14. This provides the advantage that gravity will help to transport the heavier oil particles in the housing 10 of the transmission 4.

(23) Furthermore, in the shown example the outlet opening 20 is located in the X-X plane of the drive gearwheel 14. This means the outlet opening 20 will not be located in front of or behind the X-X plane of the gearwheel 14. This will also help to remove the oil-air mixture from the housing 10.

(24) A discharge pipe 22, which connects to the outlet opening 20 and in this case extends in the X-X plane of the gearwheel 14, runs from the outlet opening 20.

(25) This discharge pipe 22 connects the housing 10 with the oil reservoir 15.

(26) The operation of the compressor 1 is very simple and as follows.

(27) During the operation of the compressor 1 the motor 3 will power the drive gearwheel 14, whereby the movement via the driven gearwheel 11 is transferred to the driven shaft 9 of the compressor element 2.

(28) Oil will be injected in the transmission 4 and possibly also the motor 3 for the cooling and/or lubrication of the gearwheels 11, 14, bearings and other parts.

(29) The operation of the compressor 1 will result in a certain pressure build-up in the transmission 4, as the air seal 12b on the driven shaft 9 will allow a certain leakage flow in the direction of the compressor element 2 toward the transmission 4.

(30) Consequently, in the housing 10 of the transmission 4 there will be an oil-air mixture at an increased pressure.

(31) The rotation of the drive gearwheel 14 will create a so-called gearwind whereby an air flow or vortex is generated by the rotating teeth of the gearwheel. This air flow is schematically shown by the arrows in FIG. 2.

(32) This flow leads the oil-air mixture that is present in the housing 10 automatically to the outlet opening 20 as it were, and thus via the discharge pipe 22 to the oil reservoir 15 and the filter element 16.

(33) Consequently, the supplied leakage air that ends ups in the housing 10 through the oil seal 12a will be immediately removed. This results in a limited negative or positive pressure in the housing 10 which falls within the permitted pressure difference of the oil seal 12a. From the outlet opening 20 the rest of the system, consisting of the discharge pipe 22, the oil reservoir 15 and the filter element 16, will be under positive pressure, which is determined by the drop in pressure over the filter element 16.

(34) A separation of the oil can take place in the filter element 16, such that clean air can be ventilated into the atmosphere. The separated oil can be collected in the oil reservoir 15 and injected back into the machine 1 via the oil circuit 17.

(35) Despite the fact that in the shown example, the outlet opening 20 is placed in the radial extension of the drive gearwheel 14 at the bottom of the housing 10, this is not necessary for the invention.

(36) The outlet opening 20 could also be placed in the radial extension of the driven gearwheel 11, or of other gearwheels if present.

(37) According to the invention it is also not necessary that it concerns a compressor 1 that is provided with a transmission 4 according to the invention. The machine 1 could also be a vacuum pump.

(38) FIG. 3 shows a variant of FIG. 2, whereby in this case the discharge pipe 22 does not extend in the radial extension of the drive gearwheel 14.

(39) However, the discharge pipe 22 is placed at an angle with the radial direction X-X of the drive gearwheel 14. However, the discharge pipe 22 still extends in the plane of the drive gearwheel 14.

(40) Thanks to this sloping placement, the discharge pipe 22 follows the direction of the gearwind more closely, such that an even better removal of the oil-air mixture from the housing 10 is obtained.

(41) Moreover, in a machine 1, whereby the discharge pipe 22 for constructive and/or design reasons is not placed in the radial extension of the drive gearwheel 14, the discharge pipe 22 can also connect to the oil reservoir 15 according to another orientation or form.

(42) For constructive and/or design reasons the drainage 20 can also be placed in front of or behind the X-X plane of the gearwheel. This by, for example, guiding the gearwind of the gearwheel via the housing 10 to the outlet opening 20.

(43) The present invention is by no means limited to the embodiments described as an example and shown in the drawings, but a transmission according to the invention and a compressor or vacuum pump equipped with such transmission can be realized in all kinds of forms and dimensions, without departing from the scope of the invention.