DUAL OR MULTI-SHAFT VACUUM PUMP

Abstract

Dual- or multi-shaft vacuum pump comprising an engine, a first shaft and at least one second shaft, wherein the first shaft and the second shaft are synchronously driven by the motor via a common drive belt. The first shaft has a pumping element and the second shaft likewise has a pumping element which cooperates with the pumping element of the first shaft in order to convey a gaseous medium from an inlet to an outlet. The first shaft has a first emergency running gear and the second shaft likewise has a second emergency running gear which meshes with the first emergency running gear.

Claims

1. A dual- or multi-shaft vacuum pump, comprising a motor, a first shaft and at least one second shaft, wherein the first shaft and the second shaft are synchronously driven by the motor via a common drive belt, wherein the first shaft has a pumping element and the second shaft has a pumping element which cooperates with the pumping element of the first shaft in order to convey a gaseous medium from an inlet to an outlet, wherein the first shaft has a first emergency running gear and the second shaft has a second emergency running gear which meshes with the first emergency running gear-.

2. The dual- or multi-shaft vacuum pump according to claim 1, wherein there in no contact of the emergency running gears in normal operation.

3. The dual- or multi-shaft vacuum pump according to claim 1, wherein the emergency running gears have a circumferential backlash to each other which is smaller than the circumferential backlash of the pumping elements to each other and which is between about 50% to about 75% of the circumferential backlash of the pumping elements.

4. The dual- or multi-shaft vacuum pump according to claim 1, wherein the emergency running gears have a circumferential backlash to each other which is greater than the circumferential backlash of the drive belt.

5. The dual- or multi-shaft vacuum pump according to claim 1, further comprising a sensor for detecting a contact of the emergency running gears.

6. The dual- or multi-shaft vacuum pump according to claim 5, wherein the sensor is a vibration sensor which detects the vibration generated by the contact of the emergency running gears.

7. The dual- or multi-shaft vacuum pump according to claim 6, wherein the tooth count of the emergency running gears is clearly selected so that unique tooth meshing frequency is generated.

8. The dual- or multi-shaft vacuum pump according to claim 1, wherein the emergency running gears are made of at least one material selected from the group consisting of: stainless steel, galvanized steel, plastic and hard-coated aluminum.

9. The dual- or multi-shaft vacuum pump according to claim 1, wherein the vacuum pump is a claw pump, screw pump or single- or multi-stage Roots pump.

10. The dual- or multi-shaft vacuum pump according to claim 1, further comprising a plurality of shafts, wherein each said shaft has an emergency running gear.

11. The dual- or multi-shaft vacuum pump according to claim 1, wherein said common drive belt is a toothed belt.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the following, the disclosure is described in more detail by means of preferred embodiments with reference to the accompanying drawings, in which

[0019] FIG. 1 shows a dual-shaft pump according to the disclosure, which is designed as a screw pump,

[0020] FIG. 2 shows a detailed view of the emergency running gears of the dual-shaft vacuum pump shown in FIG. 1 according to the disclosure, and

[0021] FIG. 3 shows a detailed view of the emergency running gears of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0022] The vacuum pump 10 according to the disclosure, which is designed as a screw pump, comprises a housing 12 having an inlet 14 and an outlet 15. A first shaft 16 is arranged in housing 12 with a first pumping element 18 being designed as a screw body in the illustrated example. Furthermore, a second shaft 20 is arranged in housing 12 with a second pumping body 22 also designed as a screw body. The first pumping element 18 and the second pumping element 22 are meshed with each other. Moreover, a motor 24 is provided which can be configured as an electric motor. By means of a drive belt 26, the first shaft 16 and the second shaft 20 are rotated or driven, respectively, by motor 24. The rotation of the shafts 16, 20 is performed in opposite direction such that a gaseous medium is conveyed from inlet 14 to the outlet. In order to generate an effective vacuum, it is required that the distance between the pumping elements 18, 22 is very small. At the same time, the pumping elements 18, 22 may not contact each other since this would result in a severe damage due to the opposite direction of rotation. The synchronization of the pumping elements 18, 22 or of the shafts 16, 20, respectively, is ensured via the drive belt 26 in normal operation. For this purpose, the circumferential backlash of the drive belt 26 is smaller than the circumferential backlash of the pumping elements 18, 22 so that a contact of the pumping elements 18, 22 is just prevented.

[0023] If an elongation of the drive arm 26, for example through wear, a loss of teeth or a tearing of the drive belt 26 occurs, it further needs to be ensured that the pumping elements 18, 22 do not come into contact with each other, which would result in a severe damage to the pumping elements 18, 22. For this purpose, the first shaft 16 has a first emergency running gear 28. Furthermore, the second shaft 20 has a second emergency running gear 30 which meshes with the first emergency running gear 28. Here, however, the emergency running gears 28, 30 do not contact each other in normal operation. Only in the event of a failure of the drive belt 26, if the synchronization of the shafts 16, 20 is no longer ensured by the drive belt 26, the emergency running gears 28, 30 come into contact with each other so that the synchronization of the shafts 16, 20 is further ensured by the emergency running gears 28, 30. Here, the emergency running gears 28, 30 have a circumferential backlash which is smaller than the circumferential backlash of the pumping elements 18, 22 to each other. It is thus ensured that the pumping elements 18, 22 further remain without contact, even upon contact of the emergency running gears 28, 30. As shown in FIG. 3, a distance A between the teeth 32 of the emergency running gears 28, 30 ensures that the emergency running gears 28, 30 remain without contact in normal operation. However, the distance A of the teeth 32 of the emergency running gears 28, 30 causes a circumferential backlash of the emergency running gears 28, 30. The distance A is selected such that the resulting circumferential backlash of the emergency running gears 28, 30 is just smaller than the circumferential backlash of the pumping elements 18, 22. On the other hand, however, the circumferential backlash of the emergency running gears 28, 30 is greater than the circumferential backlash of the drive belt 26 in normal operation. It is thus ensured that in normal operation the synchronization of the shafts 16, 20 is performed via the toothed belt 26 and that the emergency running gears 28, 30 remain without contact.

[0024] Thus, a dual- or multi-shaft vacuum pump is provided in which the synchronization of the shafts 16, 18 can be performed by means of a drive belt 26. Here, the synchronization of the shafts 16, 18 is ensured by the emergency running gears 28, 30 which just take over the synchronization of the shafts 16, 18 in the event of a failure of the drive belt 26. Thus, a safe operation of the dual- or multi-shaft vacuum pump is guaranteed. However, since in normal operation the emergency running gears 28, 30 remain just without contact, the provision of the emergency running gears 28, 30 does not require a lubricant supply.