Hydraulic drive for a pressure booster

Abstract

Hydraulic drive and method for driving a pressure booster of a high-pressure apparatus. The hydraulic drive includes a pressure medium pump having one of a constant displacement pump and a pump conveying a constant volume per revolution, a servo motor coupled to drive the pump, and a controller structured to at least one of electrically control, regulate and switch the servo motor, which is arranged on at least one of a low pressure side and a high pressure side of the pressure booster.

Claims

1. A hydraulic drive structured and arranged for a hydraulic ram pressure booster for a high-pressure apparatus for water jet cutting, the hydraulic drive comprising: a constant displacement pressure medium pump, wherein the constant displacement pump is a gerotor pump; a servo motor coupled to the constant displacement pump and operable to intermittently drive the constant displacement pump; a servo motor controller operable to vary a rotational speed of the servo motor; a two-position switch block having two operable positions, and the two-position switch block is operable to convey a pressure medium to one of two chambers of the hydraulic ram pressure booster in dependence upon a position of the two-position switch block; a pulsation damper coupled to a line that conveys the pressure medium; a low pressure signal generator that senses pressure from the pressure medium pump at a location between the pressure medium pump and the two-position switch block and outputs signals to the servo motor controller; and a high pressure signal generator that senses pressure at a location downstream of the pulsation damper and outputs signals to the servo motor controller, wherein the constant displacement pressure medium pump conveys the pressure medium to the two-position switch block; wherein the servo motor drives the constant displacement pump to drive the hydraulic ram pressure booster via the two-position switch block with a quantity control of the pressure medium fed to the hydraulic ram pressure booster governed by the rotational speed of the servo motor; wherein the servo motor controller is arranged in a closed feedback control loop with the low pressure signal generator on a low pressure side and the high pressure signal generator in order to trigger operation of the servo motor and to supply the pressure medium to the high-pressure apparatus for water jet cutting.

2. The hydraulic drive according to claim 1, the low pressure signal generator comprises a low pressure pickup/converter, and the high pressure signal generator comprises a high pressure pickup/converter.

3. The hydraulic drive according to claim 1, wherein an operating pressure sensed by the low pressure signal generator is within a range of 200-400 bar.

4. The hydraulic drive according to claim 1, wherein an operating pressure sensed by the high pressure signal generator is within a range up to 10,000 bar.

5. The hydraulic drive according to claim 4, wherein the operating pressure sensed by the high pressure signal generator is within a range of 300-6000 bar.

6. The hydraulic drive according to claim 1, wherein the servo motor comprises a frequency-controlled drive motor.

7. A method for driving a hydraulic drive for a hydraulic ram pressure booster for a high-pressure water jet cutting apparatus, the hydraulic drive comprising: a constant displacement pump, wherein the constant displacement pump is a gerotor pump; a servo motor coupled to the constant displacement pump and operable to intermittently drive the constant displacement pump; and a servo motor controller operable to vary a rotational speed of the servo motor, the method comprising: conveying a pressure medium to a two-position switch block having two operable positions with the constant displacement pump, wherein the two-position switch block is operable to convey the pressure medium to one of two chambers of the hydraulic ram pressure booster in dependence upon a position of the two-position switch block, driving the constant displacement pump via the servo motor to drive the hydraulic ram pressure booster via the two-position switch block; coupling a pulsation damper to a line that conveys the pressure medium; sensing, with a low pressure signal generator, pressure from the constant displacement pump at a location between the constant displacement pump and the two-position switch block and outputting signals to the servo motor controller; and sensing, with a high pressure signal generator, pressure at a location downstream of the pulsation damper and outputting signals to the servo motor controller; and controlling a speed of the servo motor to control a quantity of the pressure medium fed to the hydraulic ram pressure booster, wherein controlling the servo motor comprises using a closed feedback control loop with the low pressure signal generator and the high pressure signal generator in order to trigger operation of the servo motor based upon pressures sensed by the low pressure signal generator and the high pressure signal generator and to supply the pressure medium to the high-pressure water jet cutting apparatus.

8. The method according to claim 7, wherein the pressure booster comprises two hydraulic rams driven by the constant displacement pump.

9. The method according to claim 7, wherein the low pressure signal generator is a low pressure pickup/converter and the high pressure signal generator is a high pressure pickup/converter.

10. The method according to claim 7, wherein an operating pressure sensed by the low pressure signal generator is within a range of 200-400 bar.

11. The method according to claim 7, wherein an operating pressure sensed by the high pressure signal generator is within a range up to 10,000 bar.

12. The method according to claim 11, wherein the operating pressure sensed by the high pressure signal generator is within a range of 300-6000 bar.

13. The method according to claim 7, wherein the servo motor comprises a frequency-controlled drive motor.

14. A hydraulic drive structured and arranged for a hydraulic ram pressure booster for a high-pressure water jet cutting apparatus, the hydraulic drive comprising: a pressure medium pump that is one of a constant displacement pump and a pump conveying a constant volume per revolution, wherein the pressure medium pump is a gerotor pump; a servo motor coupled to the pressure medium pump and operable to intermittently drive the pressure medium pump; and a servo motor controller operable to vary a rotational speed of the servo motor; a two-position switch block having two operable positions and the two-position switch block is operable to convey a pressure medium to one of two chambers of the hydraulic ram pressure booster in dependence upon a position of the two-position switch block; a pulsation damper coupled to a line that conveys the pressure medium; a low pressure signal generator that senses pressure from the pressure medium pump at a location between the pressure medium pump and the two-position switch block and outputs signals to the servo motor controller; and a high pressure signal generator that senses pressure at a location downstream of the pulsation damper and outputs signals to the servo motor controller, wherein the pressure medium pump conveys the pressure medium to the two-position switch block having two operable positions and the two-position switch block is operable to convey the pressure medium to one of two chambers of the hydraulic ram pressure booster in dependence upon a position of the two-position switch block, wherein the servo motor drives the pressure medium pump to drive the hydraulic ram pressure booster via the two-position switch block with a quantity control of the pressure medium fed to the hydraulic ram pressure booster governed by the rotational speed of the servo motor, and wherein the servo motor controller is arranged in a closed feedback control loop with the low pressure signal generator on a low pressure side and the high pressure signal generator in order to trigger operation of the servo motor and to supply the pressure medium to the high-pressure water jet cutting apparatus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:

(2) FIG. 1 schematically illustrates a high pressure apparatus in accordance with embodiments of the invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

(3) The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.

(4) FIG. 1 diagrammatically shows a high pressure apparatus with a conveyor line 3, a pulsation damper 31 and a pressure relief valve 32 on the outlet side.

(5) A pressure booster 2 can be supplied with high-pressure fluid via series units 21, such as, for example, low pressure filters 22, booster pump 23, and shut-off valve 24.

(6) A pressure booster 2, which can, e.g., have two hydraulic rams, may be moveable by a pressure medium 10 via a hydraulic unit 1 formed by, e.g., a pump 11, e.g., a constant flow rate pump and/or a pump conveying a constant volume per revolution, and a motor 12, e.g., a servo motor, through a switch block 4. An electronic control 15 of motor 12 can be arranged to receive electrical feedback signals, e.g., by way of a closed control loop, from a high pressure pickup/converter 14 and/or from a low pressure pickup/converter 13 in order to electrically control, regulate or switch motor 12. High and low pressure pickup/converters 14 and 13 convert a sensed pressure into an electrical signal, such as a current signal, having a magnitude related to the magnitude of the pressure. By way of non-limiting example, the operating pressure on the low pressure side can be in a range of, e.g., 200-400 bar, while the operating pressure on the high pressure side can be in a range of, e.g., 3000-6000 bar, and up to 10,000 bar in, e.g., test systems.

(7) A feed of pressure booster 2 can be carried out in a known manner, e.g., by bent axis displacement pumps with hydraulic mechanical quantity controllers with parallel acting cylinders, the conveyor flows of which are added together.

(8) In the case of direct axial alignment, an immediate reduction of the pump performance of pressure medium to zero can be achieved despite a motor rotation.

(9) A high pressure apparatus such as, for example, a water jet cutting plant usually has longer lasting work phases, so that a drive of a pressure booster via a servo motor and a pump with constant quantity pumping must appear far removed from a conventional technically advantageous solution to one with skill in the art.

(10) Surprisingly, it has been shown that a use of a constant displacement pump 11 driven by a servo motor 12 has advantages when used as part of a hydraulic drive 1 in accordance with embodiments of the invention for a pressure booster 2 of a high pressure apparatus.

(11) Among other things, this arrangement results in extremely low pulsations of a high-pressure water jet, which does not cause any chipping in the case of brittle materials even when cutting a through hole. Moreover, this may advantageously be achieved through the use of a gerotor pump 11 for a hydraulic drive 1 of a pressure booster 2.

(12) According to embodiments, hydraulic drive 1 can be utilized in accordance with the invention to cause low pulsations and in particular slight high-pressure fluctuations in the case of a stop/go operation of a system. In this way, the service life of the high pressure components is increased.

(13) In an advantageous manner with closed high-pressure nozzles, no movement of the servo motor and no power consumption of the same take place. In this manner, the start power consumption can be reduced with a soft start of the hydraulic drive 1.

(14) It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.