Diaphragm cell for damping pressure pulsations in a low-pressure region of a piston pump

Patent metadata

Field	Value
Publication number	US-10662931-B2
Application number	US-201615756447-A
Country	US
Kind code	B2
Filing date	Aug 10, 2016
Priority date	Oct 8, 2015
Publication date	May 26, 2020
Grant date	May 26, 2020

Abstract

A diaphragm cell for damping pressure pulsations in a low-pressure region of a piston pump has two axially deformable diaphragms that are connected along their radial peripheries and enclose a gas space. The diaphragms each have a central region that extends over no less than 50% of the cross-sectional surface area of the diaphragms. The diaphragms are of undulating shape in the central region, which is curved axially outwards in its radially inner region and in its radially outer region. The diaphragms further include an axially inwardly curved annular region that is arranged between and immediately adjacent to the radially inner region and the radially outer region. An axially-measured amplitude of the wave shape has a predetermined range related to the cross-sectional surface area of the diaphragms when the pressure difference is zero. The pressure difference is a pressure in the gas space minus a pressure outside the gas space.

First claim

The invention claimed is:

1. A diaphragm cell for damping pressure pulsations in a low-pressure region of a piston pump, comprising:
two diaphragms that are connected to one another at their radial edges and enclose a gas space, wherein:
the two diaphragms are both axially deformable in an axial direction,
the two diaphragms each have a central region which is central in an axial top view of the diaphragm cell, and in the axial top view of the diaphragm cell the central region extends over not less than 50% of the cross-sectional area of the two diaphragms,
the two diaphragms are shaped in an undulating fashion in the central region, the central region being curved outward in the axial direction in a radially inner region and in a radially outer region,
an annular region which is annular in a top view (i) is arranged between the radially inner region and the radially outer region and (ii) in each case is directly adjacent to the radially inner region and the radially outer region, the annular region being curved inward in the axial direction,
an amplitude of the wave shape measured in the axial direction is at least 1/1000 and at most 2/100 of the square root of 4/π times the cross-sectional area of the two diaphragms when in a pressure-equalized state in which a pressure difference is zero during operation of the piston pump,
the pressure difference is a pressure in the gas space minus a pressure outside the gas space, in the low-pressure region of the piston pump, and
the pressure outside the gas space varies such that an interval between the resulting pressure differences spans at least 3 bar and includes the pressure-equalized state.

2. The diaphragm cell as claimed in claim 1 , wherein a distance measured in a radial direction between a maximum curvature in the radially inner region and a maximum curvature in the radially outer region is ⅕ of the square root of 4/π times the cross-sectional area of the two diaphragms.

3. The diaphragm cell as claimed in claim 1 , wherein the radially inner region is curved further outward in the axial direction than the radially outer region.

4. The diaphragm cell as claimed in claim 1 , wherein the radially inner region and the radially outer region are curved outward to an equal extent in the axial direction.

5. The diaphragm cell as claimed in claim 1 , wherein the central region is surrounded radially by a further annular region of the two diaphragms, which is a flat portion of each diaphragm in the diaphragm cell, the flat portions are located one on top of the other and are tightly connected to one another at their radial edges.

6. The diaphragm cell as claimed in claim 5 , wherein the two diaphragms are tightly welded to one another at their radial edges in the further annular region.

7. The diaphragm cell as claimed in claim 1 , wherein:
one or more of:
(i) at least one of the two diaphragms, the central region, and the radially inner region has, in the axial top view, a round shape, and
(ii) at least one of the annular region, the radially outer region, and a further annular region has, in the axial top view, a round outer contour, and

the entire diaphragm cell is symmetrical with respect to an axis of symmetry.

8. The diaphragm cell as claimed in claim 1 , wherein the gas space is filled with a gas, and wherein the gas has a pressure of 3 to 10 bar at 40° C. when the pressure difference is zero.

9. The diaphragm cell as claimed in claim 1 , wherein the two diaphragms are each shaped from planar sheet-metal in a single deep-drawing step.

10. The diaphragm cell as claimed in claim 1 , wherein a resilience of the diaphragm cell, which is a change in a volume of the gas space per change in the pressure difference, is greatest when the pressure difference is zero.

11. The diaphragm cell as claimed in claim 1 , wherein a resilience of the diaphragm cell, which is a change in a volume of the gas space per change in the pressure difference, in the interval is at least 60% of a maximum resilience of the diaphragm cell.

12. A piston pump, comprising:
a low-pressure region; and
at least one diaphragm cell arranged in a low-pressure region fluidically between an inflow connection of the piston pump and an inlet valve of the piston pump, the at least one diaphragm cell including:
two diaphragms that are connected to one another at their radial edges and enclose a gas space, wherein:
the two diaphragms are both axially deformable in an axial direction,
the two diaphragms each have a central region which is central in an axial top view of the diaphragm cell, and in the axial top view of the diaphragm cell the central region extends over not less than 50% of the cross-sectional area of the two diaphragms,
the two diaphragms are shaped in an undulating fashion in the central region, the central region being curved outward in the axial direction in a radially inner region and in a radially outer region,
an annular region which is annular in a top view (i) is arranged between the radially inner region and the radially outer region and (ii) in each case is directly adjacent to the radially inner region and the radially outer region, the annular region being curved inward in the axial direction,
an amplitude of the wave shape measured in the axial direction is at least 1/1000 and at most 2/100 of the square root of 4/π times the cross-sectional area of the two diaphragms when in a pressure-equalized state in which a pressure difference is zero during operation of the piston pump,
the pressure difference is a pressure in the gas space minus a pressure outside the gas space, in the low-pressure region of the piston pump, and
wherein the pressure outside the gas space varies such that an interval between the resulting pressure differences spans at least 3 bar and includes the pressure-equalized state.

13. The piston pump as claimed in claim 12 , wherein the diaphragm cell is secured by two securing parts at the radial edges of the two diaphragms.

14. The piston pump as claimed in claim 13 , wherein the diaphragm cell is secured between a housing of the piston pump and a cover of the piston pump, the cover being welded onto the housing of the piston pump.

15. A method for operating a piston pump that includes a low-pressure region and at least one diaphragm cell arranged in the low-pressure region fluidically between an inflow connection of the piston pump and an inlet valve of the piston pump, the method comprising:
selecting a pressure in the low-pressure region of the piston pump to be equal to a pressure in a gas space of the diaphragm cell, the diaphragm cell including:
two diaphragms that are connected to one another at their radial edges and enclose the gas space, wherein:
the two diaphragms are both axially deformable in an axial direction,
the two diaphragms each have a central region which is central in an axial top view of the diaphragm cell, and in the axial top view of the diaphragm cell the central region extends over not less than 50% of the cross-sectional area of the two diaphragms,
the two diaphragms are shaped in an undulating fashion in the central region, the central region being curved outward in the axial direction in a radially inner region and in a radially outer region,
an annular region which is annular in a top view (i) is arranged between the radially inner region and the radially outer region and (ii) in each case is directly adjacent to the radially inner region and the radially outer region, the annular region being curved inward in the axial direction,
an amplitude of the wave shape measured in the axial direction is at least 1/1000

Assignees

• Bosch Gmbh Robert

Inventors

• Schretling Viktor
• Schenk Tobias

Classifications

• F16F2224/0208

  Alloys · CPC title

• F16F2226/04

  Assembly or fixing methods; methods to form or fashion parts · CPC title

• F04B39/0061

  using muffler volumes · CPC title

• F04B11/0008 Primary

  using accumulators · CPC title

• F04B11/0016 Primary

  with a fluid spring · CPC title