METHOD FOR PRODUCING A FOAM BODY

• US 20180038391A1
• Filed: 01/15/2016
• Published: 02/08/2018
• Est. Priority Date: 03/20/2015
• Status: Active Grant

• Current Assignee: Hydac Technology Gmbh (HYDAC International GmbH)
• Original Assignee: Hydac Technology Gmbh (HYDAC International GmbH)
• Inventors: KLOFT, Peter, BALTES, Herbert
• Granted Patent: US 10,641,295 B2
• Time in Patent Office: Days
• CPC Class Codes: F15B 1/086 the gas cushion being entirely enclosed by the separating means, e.g. foam or gas-filled balls
• CPC Class Codes: F15B 2201/3152 the flexible separating means being bladders
• CPC Class Codes: F15B 2201/3154 the flexible separating means being completely enclosed, e.g. using gas-filled balls or foam
• CPC Class Codes: F15B 2201/411 having valve means
• CPC Class Codes: F15B 2201/60 Assembling or methods for making accumulators

Abstract

A method for producing a foam body, in particular for a pressure accumulator, such as a hydraulic accumulator, the bubble- or diaphragm-shaped, elastically flexible separating layer (12) of which separates two media chambers from each other within the accumulator housing, in particular a gas working chamber from a liquid chamber (18), with at least the following production method steps: —introducing a flowable, preferably liquid, foam material into the pressure accumulator, said foam material being at least partially surrounded by the separating layer (12), —curing the foam material in the pressure accumulator, and in the process—building up a pressure gradient, in which the visibly curing foam material expands the separating layer (12) from an originally partially filled starting state in the direction of an end state, in which the accumulator is finally filled with the cured foam (38).

Claims

1. A method for producing a foam body, in particular for a pressure accumulator (10), such as a hydraulic accumulator, the bladder- or diaphragm-shaped, elastically flexible separating layer (12) of which separates two media chambers from each other within the accumulator housing (14), in particular a gas working chamber (16) from a fluid chamber (18), comprising at least the following production method steps:

introduction of a flow-capable, preferably fluid, foam material (28) into the pressure accumulator (10), which is at least partially surrounded by the separating layer (12),

hardening of the foam material (28) in the pressure accumulator (10), and thereby

building up a pressure gradient, in which the increasingly hardening foam material (28) expands the separating layer (12) from an original partially-filled starting state towards a final state, in which the accumulator (10) is finally filled with the hardened foam (38).

2. The method according to claim 1, characterized in that, by means of the hardening foam material (28) that is introduced into the pressure accumulator (10) and with build-up of the associated pressure gradient, the separating layer (12) is expanded until such time as a valve provided in the fluid chamber (18) of the accumulator (10), in particular in the form of a poppet valve (24), is closed.

3. The method according to claim 1, characterized in that the flow-capable, in particular fluid, foam material (28), is sprayed or injected by means of a lance-shaped input device (36) into the pressure accumulator (10), with the one free end of said input device opening into the top half of the pressure accumulator (10) and being guided in the gas working chamber (16) and thereby penetrating the gas connection (20) of the accumulator (10) and with the other free end of the input device outside of the pressure accumulator (10) being connected to an admixing device(30).

4. The method according to claim 1, characterized in that, by means of the admixing device (30), which is formed as a dynamically or statically functioning mixing head (32), components of the flow-capable, in particular fluid foam material (28) are supplied to the mixing head (32) via at least two supply lines (34) connected to said mixing head in order to subsequently be introduced in a corresponding predeterminable mix ratio via the lance-shaped input device (36) into the gas working chamber (16) of the accumulator (10).

5. The method according to claim 1, characterized in that the individual components which are to be mixed with one another by means of the admixing device (36) in order to create the flow-capable, in particular fluid foam material (28) are selected as follows:

polyols, in particular in the form of long-chain polyether polyols;

foaming agents, in particular in the form of water; and

crosslinkers, in particular in the form of diglycolamine, preferably supplemented with;

catalysts, in particular in the form of amine catalysts and/or tin catalysts;

retarders;

flame retardants; and

stabilizers, in particular in the form of silicone compounds.

6. The method according to claim 1, characterized in that the foam material (38) hardened in situ in the pressure accumulator (10) is formed with open cells with a recovery capability as a 3D structure of 97 to 98%.

7. The method according to claim 1, characterized in that the volumetric weight of the hardened foam material (38) is selected in a range from 50 g/dm³ to 150 g/dm³ per liter of input volume of flow-capable, in particular fluid foam material (28).

8. The method according to claim 1, characterized in that the heat capacity of the hardened foam material (38) is selected at 20°

C.>

1 J/gK.

9. The method according to claim 1, characterized in that the flow resistance of the foam (38) is selected in a range from 1400 to 3800 Ns/m³.

10. The method according to claim 1, characterized in that the temperature stability in a closed accumulator bladder (12) as the elastically flexible separating element and with insertion of dry inert gas as the working gas introduced into the gas working chamber (16) of the accumulator (10) is selected in a range from −

40°

C. to 140°

C.

11. The method according to claim 1, characterized in that, on the basis of the respective selected expansion speed together with the pressure gradient values during foaming, cells are obtained in the finished foam (38) in the range from 0.01 mm³ to 375 mm³.