| SE324706B | 1970-06-08 | |||
| US1888990A | 1932-11-29 | |||
| US3186173A | 1965-06-01 | |||
| US4864914A | 1989-09-12 |
| 1. | Hydraulic system for a hydraulic pressure booster for a hydraulic ram comprising a pump (1) , a check valve (2) , a pressure switch (5) , a control valve (7) , a pressure booster (8A) , a pressure ram (8B) , and a pressure limiting valve (6) , c h a r a c t e r i z e d in that when the hydraulic pressure of the pump (1) acts on the pressure boosterpressure ram (8) the piston rod of the pressure booster (8A) is pressed backwards and the pressure booster is filled with oil, the piston rod of the pressure ram (8B) at the same time being pressed outwards, and when the hydraulic pressure reaches the value set on the pressure switch (5) the high pressure valve (7) is switched so that the oil from the pump (1) passes to the piston side of the pressure booster (8A) and supplies oil from the piston rod side at a higher pressure than the pump pressure to the pressure ram (8B) , and when the pressure falls again below the pressure set on the pressure switch (5) the high pressure valve (7) is again switched and the procedure starts automatically again from the beginning. |
| 2. | System according to claim 1, c h a r a c t e r i z e d in that the pressure booster (8A) is arranged in the piston rod (9) of the pressure ram (8B) so that oil from the pump (1) to the pressure ram (8B) is supplied at (A) , the piston rod (9) of the pressure ram (8B) being pressed outwards and the piston rod (10) of the pressure booster (8A) being pressed backwards by the oil via the passage (D) and the pressure booster at the same time being filled with oil, and when oil is supplied via (C) the pressure booster (8A) acts via the passage (D) on the piston (11) of the pressure ram (8B) the piston rod side of the pressure booster (8A) at the same time being drained via the passage (E) . |
The invention below relates to a device which increases automatically the force in a hydraulic ram by means of a pressure booster which is filled automatically with oil and at the same time can provide a pulsating force in the tool actuated by the ram.
Background
When e.g. a pile or a sheet pile is to be gripped by means of a hydraulic clamp yaw for vibration or extraction great mechanical forces must be exerted by means of e.g. a hydraulic ram. This is true also in respect of hydraulic so called concrete crushers or shears which are mounted to contractor's equipment of some type for demolition work or sorting work for re-use of e.g. concrete and reinforcing iron. Contractor's equipment available today operates with an hydraulic pressure of about 20 to 40 Mpa. In order that the hydraulic rams shall not have too large dimensions some type of pressure booster can be used which increases the hydraulic pressure over the normal operating pressure. This is prior art technique.
Characterizing features
At large movements with the pressure booster connected or at minor leakage when the clamp force shall act for a long time it is necessary today that the pressure booster operates with large volumes or it is necessary to interrupt and return to the initial position and to start again when the capacity of the pressure booster is completely exploited. This involves expensive components or disturbances and trouble when the work is being performed. By means of the invention below this inconvenience is eliminated because the force is automatically increased without interruption of the working cycle or extra work
steps. The pressure booster will be automatically filled and moreover the working process will be improved e.g. for a concrete crusher where it is advantageous to have a force of pulsating character.
Description of drawings
FIG. 1 discloses a hydraulic diagram for a pressure ram with pressure booster.
FIG. 2 discloses a hydraulic ram with integrated pressure booster.
Description of an illustrative embodiment
A hydraulic circuit is set up according to FIG. 1 and comprises a hydraulic pump 1, a check valve 2, a pressure limiting relief valve 3, a control valve 4, a pressure switch 5, a pressure limiting valve 6, a control valve 7, and a pressure booster with pressure ram 8.
The oil passes from pump 1 via valve 4 to the pressure booster/ram 8. The piston rod of the pressure ram 8B will be pressed outwards and the piston rod of the pressure booster 8A will be pressed backwards, the pressure booster at the same time being filled with oil. When the pressure reaches the value set on the pressure switch 5 valve 7 will be switched to pass the oil to pressure booster 8A which presses the oil into pressure ram 8B which then, due to the area difference in the pressure booster will be pressurized at a higher pressure than the operating pressure of the pump. When the pressure acting on pressure switch 5 falls below the pressure set due to the fact that a lower pressure is required on the pressure ram 8B or due to the fact that pressure booster 8A reaches the bottom position, pressure switch 5 will switch valve 7. The piston rod of pressure booster 8A will be pressed backwards and at the same time the pressure booster will be filled with oil, and when the required pressure increases again over the
value set on pressure switch 5 valve 7 will be switched again and pressure booster 8A will start operating again. The operation is completely automatic and will be repeated as long as valve 4 is in position A. Return movement of pressure ram 8B can be obtained for example by switching valve 4 to position B.