Pump unit driven by an electric motor
The invention relates to a pump unit that can be driven by an electric motor, in particular for providing vacuum for a pneumatic brake booster, including a pump housing that can be closed by a working-chamber cover and at least one elastic displacement element, wherein a working chamber is bounded between the displacement element and the working-chamber cover and wherein inlet valves and outlet valves and inlet channels and outlet channels associated with the valves are associated with the working chamber. According to the invention, in order to reduce noise emissions, devices for reducing a contact surface between the working-chamber cover and the pump housing are provided.
1. A pump unit that can be driven by electric motor, for the generation of negative pressure for a pneumatic brake force booster, comprising a pump housing that can be closed off by a working chamber cover and comprising at least one elastic displacement element, wherein a working chamber is delimited between the displacement element and the working chamber cover, and said working chamber is assigned in each case inlet and outlet valves and inlet and outlet ducts assigned to the valves, at least three protuberances extending from one of the working chamber cover and the pump housing for reducing an area of contact between the working chamber cover and the pump housing, and a decoupling element positioned between the at least three protuberances extending from the one of the working chamber cover and the pump housing and the other one of the working chamber cover and the pump housing.
2. The pump unit that can be driven by electric motor as claimed in claim 1 , wherein the at least three protuberances are distributed over the circumference of a housing flange, such that a spatially stable support is realized between the working chamber cover and the pump housing.
3. The pump unit that can be driven by electric motor as claimed in claim 1 , wherein the working chamber cover has a top cover and a bottom cover with a lower bottom cover flange, and the at least three protuberances are distributed over the circumference of the lower bottom cover flange, such that a spatially stable support is realized between the working chamber cover and the pump housing.
4. The pump unit that can be driven by electric motor as claimed in claim 1 , wherein the working chamber cover has a top cover with a top cover flange and has a bottom cover with an upper bottom cover flange, wherein the at least three protuberances are provided between the top cover and the bottom cover.
5. The pump unit that can be driven by electric motor as claimed in claim 4 , wherein the at least three protuberances distributed over the circumference of the top cover flange or of the upper bottom cover flange, such that a spatially stable support is realized between the top cover and the bottom cover.
6. The pump unit that can be driven by electric motor as claimed in claim 2 , wherein the working chamber cover is separated from the pump housing, and/or the top cover is separated from the bottom cover, by the decoupling element for the purpose of reducing a transmission of vibrations.
7. The pump unit that can be driven by electric motor as claimed in claim 6 , wherein the elastic decoupling element is connected to at least one seal element to form a gasket.
8. The pump unit that can be driven by electric motor as claimed in claim 1 , wherein at least one insert part that can be loaded in a valve opening direction by a valve plate is arranged, so as to be secured against rotation, in the inlet or the outlet duct.
9. The pump unit that can be driven by electric motor as claimed in claim 8 , wherein the insert part has means for locking the insert part in corresponding locking openings, wherein the locking openings are provided in the bottom cover.
10. The pump unit that can be driven by electric motor as claimed in claim 8 , wherein the insert part has at least one impact surface, which is rounded in a valve opening direction, for the abutment of the valve plate during the valve opening process.
11. The pump unit that can be driven by electric motor as claimed in claim 1 , wherein the bottom cover has a valve support surface for the support of the valve plate in a closed valve state, wherein at least one recess for reducing an area of contact between the valve plate and the valve support surface is arranged in the valve support surface.
12. The pump unit that can be driven by electric motor as claimed in claim 1 , wherein the pump unit can be fastened in elastically vibration-decoupled fashion in a base holder, wherein the elastic decoupling is realized by means of damping elements, wherein the base holder has supporting elements for receiving damping elements, and wherein at least one supporting element is manufactured by deformation of the base holder.
13. The pump unit that can be driven by electric motor as claimed in claim 1 , wherein the pump unit can be fastened in elastically vibration-decoupled fashion in a base holder, wherein the elastic decoupling is realized by damping elements, wherein at least one of the damping elements has an inner shell with a conical inner contour and an outer shell, wherein the inner shell is connected to the outer shell by an encircling collar and by radial webs arranged at least on one side of the collar.
14. The pump unit that can be driven by electric motor as claimed in claim 1 , wherein an air outlet unit, which is pneumatically connected to the outlet duct, for the discharge of the air into the surroundings of the pump unit is provided, wherein the air outlet unit has an intermediate base with at least one passage opening, wherein the intermediate base comprises means closing the passage openings, in water-tight fashion in the direction of the outlet duct, in the manner of a check valve.
15. The pump unit that can be driven by electric motor as claimed in claim 14 , wherein the means for closing passage openings are in the form of an elastically resilient tab that is integrally formed on the intermediate base.
16. The pump unit that can be driven by electric motor as claimed in claim 1 , wherein an air outlet unit, which is pneumatically connected to the outlet duct, for the discharge of the air into the surroundings of the pump unit is provided, wherein the air outlet unit has a check valve with an elastic valve disk, and the check valve closes pneumatically in the direction of the outlet duct, wherein the valve disk is loaded counter to the valve opening direction by an elastic element.
17. The pump unit that can be driven by electric motor as claimed in claim 16 , wherein a disk element is provided so as to be arranged between the elastic element and the valve disk.
18. The pump unit that can be driven by electric motor as claimed in claim 16 , wherein the elastic element is in the form of a spiral spring.
19. The pump unit that can be driven by electric motor as claimed in claim 1 , wherein the pump unit is driven by an electric drive unit, wherein at least two elastic intermediate elements are interposed, so as to act in parallel, between the pump housing and the drive unit, wherein an inner intermediate element is provided for pneumatic and hydraulic sealing with respect to the surroundings of the pump unit, and an outer intermediate element is provided for a vibration decoupling of the drive unit from the pump housing, and wherein the intermediate elements are connected to one another by at least two elastic connecting webs.
20. The pump unit that can be driven by electric motor as claimed in claim 1 , wherein the displacement element has an elastic diaphragm element and a connecting rod element, wherein the diaphragm element is non-detachably connected to the connecting rod element by an insert molding process, wherein the connecting rod element is of unipartite form and has a shank part and a connecting rod ring part.