Compressor or vacuum pump provided with a transmission

Abstract

A compressor provided with a compressor element with a driven shaft, a motor with a drive shaft to drive the compressor element, and a transmission between the drive shaft and the driven shaft. The 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 includes two separated chambers, a first chamber that is connected to the driven shaft and a second chamber which is separate from the first chamber. The first chamber is connected via a channel with the second chamber, whereby around the drive gearwheel or driven gearwheel, the second chamber is formed. The form of the second chamber is such that when the gearwheel in question rotates, a gas flow is created around this gearwheel which causes a negative pressure in the channel by the venturi effect.

Claims

1. A compressor comprising with a compressor element with a driven shaft and a motor with a drive shaft to drive the compressor element, said compressor further being provided with a transmission between said drive shaft and said driven shaft, which the transmission comprising a housing and at least a driven gearwheel that is mounted on the driven shaft and a drive gearwheel that is mounted on the drive shaft, wherein the housing comprises two separated chambers, a first chamber that is connected to the driven shaft and a second chamber which is separate from the first chamber, whereby the first chamber is connected via a channel with the second chamber, whereby around the drive gearwheel or driven gearwheel the second chamber is formed, whereby the form of the second chamber is such that when the gearwheel in question rotates a gas flow is created around this gearwheel which causes a negative pressure in the channel by a venturi effect; wherein a distance in a radial direction between a wall of the second chamber and the gearwheel in question gets bigger in a rotation direction of the gearwheel in question.

2. The compressor according to claim 1, wherein the second chamber is integrated in a wall of the housing.

3. The compressor according to claim 1, wherein the second chamber extends along the gearwheel with a greatest diameter and/or a greatest peripheral speed.

4. The compressor according to claim 1, wherein the second chamber extends from 0° to 225° of a circumference of the gearwheel in question starting from a position of engagement of the gearwheels.

5. The compressor according to claim 1, wherein an opening of the second chamber is 25% to 75% of a circumference of the gearwheel in question.

6. The compressor according to claim 5, wherein the opening of the second chamber is 45% to 55% of the circumference of the gearwheel in question.

7. The compressor according to claim 6, wherein the opening of the second chamber is 50% of the circumference of the gearwheel in question.

8. The compressor according to claim 1, wherein said channel connects to an end of the second chamber, as seen in a rotation direction of the gearwheel in question.

9. The compressor according to claim 1, wherein said second chamber is in connection with a filter element or the like connected to the transmission.

10. A vacuum pump comprising with a vacuum pump element with a driven shaft and a motor with a drive shaft to drive the vacuum pump element, said vacuum pump further being provided with a transmission between said drive shaft and said driven shaft, wherein said 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 the drive shaft, and wherein the housing comprises two separated chambers, a first chamber that is connected to the driven shaft and a second chamber which is separate from the first chamber, whereby the first chamber is connected via a channel with the second chamber, whereby around the drive gearwheel or driven gearwheel the second chamber is formed, whereby the form of the second chamber is such that when the gearwheel in question rotates a gas flow is created around this gearwheel which causes a negative pressure in the channel by a venturi effect; wherein a distance in a radial direction between a wall of the second chamber and the gearwheel in question gets bigger in a rotation direction of the gearwheel in question.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) With the intention of better showing the characteristics of the invention, a few preferred embodiments of a compressor or vacuum pump according to the invention 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 compressor according to the invention;

(3) FIG. 2 shows the transmission of FIG. 1 in detail;

(4) FIG. 3 shows a view according to the arrow F3 in 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) A filter element 16 is connected to the housing 10 of the transmission 4, to be able to filter oil out of the oil-air mixture that is in the housing 10 of the transmission 4.

(16) In this case, but not necessarily, the housing 10 of the transmission 4 is connected to an oil reservoir 15 to collect the injected oil and this oil reservoir 15 is provided with a filter element 16.

(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 with an oil pump 18, i.e. the oil that flows back out of the housing 10 and the oil separated by the filter element 16, 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 comprises two chambers 20 and 22. A first chamber 20 which is connected to the driven shaft 9 and a second chamber 22 which is separate from the first chamber 20. This is shown in FIG. 2.

(19) As one can tell from FIG. 2, the driven shaft 9 extends into the first chamber 20.

(20) The second chamber 22 is provided around the drive gearwheel 14. The first chamber 20 is connected to this second chamber 22 via the channel 21.

(21) The form of the second chamber 22 is shown clearly in FIG. 3.

(22) In this case, the second chamber 22 is integrated in the wall 23 of the housing 10 of the transmission 4.

(23) However, it is also possible that the transmission 4 is provided with a shield that is mounted next to, around or against the gearwheel 14 and that is provided with a form similar to the second chamber 22. Such shield can be mounted in the housing 10. This provides the advantage that nothing needs to be changed to a possible existing housing 10.

(24) The second chamber 22 is such that the “gearwind” that is created by rotation of the drive gearwheel 14 is led along the channel 21 such that a negative pressure is caused in the channel 21 because of the venturi effect.

(25) As can be seen in FIG. 3, the second chamber 22 gets bigger in the rotation direction of the drive gearwheel 14, as was indicated with arrow P. Said channel 21 also connects to the end of the second chamber 22 as seen in the rotation direction P of the drive gearwheel 14, i.e. to its biggest end.

(26) Both characteristics will ensure that said effect will be as optimal as possible.

(27) The second chamber 22 extends from 0° to approximately 225° of the circumference of the drive gearwheel 14 in the rotation direction of arrow P, starting from the engagement of the gearwheels.

(28) Preferably, the rest of the circumference of the drive gearwheel 14 forms a tight fit.

(29) This will ensure that the vortex losses are reduced to a minimum.

(30) As can be seen in FIG. 1, the second chamber 22 is connected to the filter element 16 that is connected to the transmission 4. This filter element 16, for example, can be a venting filter or a liquid separator that is provided with a filter.

(31) Because the oil separation in the filter element 16 is always linked with a certain drop in pressure the result will be a positive pressure in the second chamber 22.

(32) This means extra vortex losses in the second chamber 22.

(33) According to the form of the second chamber 22, as shown in FIG. 3, the reduction of the vortex losses by the tight fit of the drive gearwheel 14 and the extra vortex losses in the second chamber 22 due to pressure build-up over the filter element 16 will cancel each other out which means no extra power of the motor 3 is necessary.

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

(35) 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.

(36) 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.

(37) 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.

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

(39) The rotation of the drive gearwheel 14 will create a so-called “gearwind” in the chamber 22 whereby an air flow or vortex is generated by the rotating teeth of the drive gearwheel 14.

(40) By channeling this air flow along the channel 21 the venturi effect will cause a negative pressure in the channel 21.

(41) As a result of this negative pressure, the first chamber 20 will be sucked out as it were and the oil-air mixture in this chamber will end up in the second chamber 22 via the channel 21.

(42) This causes a pressure difference between the first chamber 20 and the second chamber 22, whereby the pressure in the first chamber 20 will be lower than the pressure in the second chamber 22.

(43) The lower pressure in the first chamber 20 prevents the seals 12a, 12b on the driven shaft 9 from being exposed to too big a pressure difference, such that it is avoided that the oil-air mixture can end up in the compressor element 2.

(44) The oil-air mixture ends up in the second chamber 22, where a pressure build-up will take place due to the drop in pressure over the filter element 16 after which the purified, oil-free air can be channeled out.

(45) The oil separated in the filter element 16 can then be injected back into the transmission 4 and/or the motor 3 via the oil circuit 17.

(46) Although in the shown example the second chamber 22 is provided around the drive gearwheel 14, it is not excluded that this chamber 22 is provided around the driven gearwheel 11 or another gearwheel, if present.

(47) However, preferably this chamber 22 extends along the gearwheel 11, 14 or another gearwheel, if present, with the greatest diameter and/or the greatest peripheral speed.

(48) As is visible in FIG. 3, the drive gearwheel 14 in this case is greater than the driven gearwheel 11 and the second chamber 22 is therefore also provided around the drive gearwheel 14.

(49) The bigger gearwheel 14 will, after all, be able to create a greater gas flow, such that the negative pressure in the channel 21 is greater and a better extraction of the first chamber 20 is obtained.

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

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