Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B3/00—Intensifiers or fluid-pressure converters, e.g. pressure exchangers; Conveying pressure from one fluid system to another, without contact between the fluids

Definitions

• the present invention relates generally to the generation of fluid pressure for use in diverse applications, and specifically concerns the boosting of hydraulic fluid pressure.
• a conventional apparatus for intensifying hydraulic fluid pressure comprises a low pressure piston moveable in a low pressure cylinder and carrying a high pressure piston moveable in a high pressure cylinder and having a significantly smaller effective area than the low pressure piston.
• the low pressure piston divides the low pressure cylinder into a working stroke chamber having a low pressure fluid inlet, and a return chamber likewise having a low pressure fluid inlet.
• the high pressure cylinder is provided with a low pressure inlet and a high working pressure outlet.
• seals are provided between the high pressure and low pressure sides, to eliminate fluid leakage from the high pressure cylinder, thereby effectively securing the intended raised fluid pressure level in the high pressure chamber.
• seals are also important to secure that high pressure fluid does not escape past the seals, since it might otherwise mix with the low pressure fluid and adversely affect the efficiency of the intensifier apparatus. For the continued effective operation of the pressure intensifier, it is therefore vital to provide appropriate seals.
• said upper limit is in the range of approximately 2000bar, although attempts are frequently made to operate pressure intensifiers with higher pressures. However, such high pressure operation inevitably results in very short service intervals since the high pressure seals will have a useful life of only a few hours.
• the invention overcomes the above discussed problems in an efficient and satisfactory manner. It is a general object of the invention to provide a solution to the problem of effectively and reliably generating high hydraulic pressure.
• this is achieved in a favorable manner by eliminate the exposure of the high pressure seals to the very high pressure during the initial phase of the working stroke of the apparatus. Specifically, this is accomplished by providing a restricted outflow of hydraulic fluid from the high pressure chamber during the initial phase of the working stroke of the apparatus.
• the continuous restricted outflow of hydraulic fluid is provided from the start of the working stroke of the apparatus, said outflow being blocked when the forward end of the high pressure piston has passed the high pressure seal. In this manner, the seal will be effectively protected during the entire working stroke of the apparatus.
• the continuous restricted outflow of hydraulic fluid from the high pressure chamber as well as from the consumer is provided during the final phase of the return stroke of the apparatus.
• the very high pressure generated in the consumer as well as in the high pressure cylinder, by the working stroke of the apparatus will be relieved in a very favorable manner, causing no damage to either the apparatus or to associated equipment.
• the continuous restricted outflow of hydraulic fluid from the high pressure chamber is provided during a phase of flushing the high pressure chamber with hydraulic fluid immediately prior to performing the working stroke.
• This controlled outflow of high pressure fluid from the high pressure cylinder before the working stroke allows air from the pressure medium to be flushed out from the high pressure cylinder prior to the working stroke.
• Another object of the invention is to provide an improved and very effective apparatus for generating high hydraulic fluid pressure, securing effective long-term operation thereof with a minimum of shutdowns for service and repair.
• this is achieved in a favorable manner by providing a central bore extended through the high pressure piston of the apparatus, said bore having a restrictor for permitting fluid flow from the high pressure chamber, a check valve for blocking fluid flow from the high pressure chamber and a valve operating rod for selectively opening the check valve.
• a controlled outflow of fluid from the high pressure chamber is permitted during at least the initial phase of the working stroke of the apparatus to eliminate the exposure of the high pressure seals to very high pressure during said initial phase.
• the present invention provides for the following advantages over the state of the art:
• Fig. 1 is a partial plan view from one side, illustrating an embodiment of an apparatus according to the present invention
• Fig. 2 is a longitudinal section through the apparatus of fig. 1 ,
• Fig. 3 A is an end view of the apparatus as seen from the high pressure side thereof being to the left in figs. 1 and 2,
• Fig. 3B is an end view of the apparatus as seen from the low pressure side thereof being to the right in figs. 1 and 2,
• Fig. 4A-B are enlarged views of the high pressure piston illustrated in two positions
• Fig. 5A is a plan view from one side, illustrating an embodiment of a simplified pressure intensifying apparatus according to the present invention.
• Fig. 5B is an end view of the end of the apparatus being to the left in fig. 6 A.
• Fig. 1 illustrates the general design of an embodiment of the inventive apparatus 1 for genera- ting high fluid pressure.
• the apparatus consists of a low pressure cylinder 2 provided to the right in figs. 1 and 2 and a high pressure cylinder 3 provided to the left in figs. 1 and 2.
• the terms "front” and “rear” are used to indicate the positions of parts or portions of the apparatus relative to the direction of the working stroke of the apparatus, meaning that a "front” portion is positioned towards the high pressure side of the apparatus compared to a "rear” portion.
• low pressure refers to a pressure that is low compared to the high pressure output from the apparatus, but that is not necessarily low in other respects or applications.
• a rear end wall 4 closes the low pressure cylinder 2 outwardly and a front end wall 5 closes the high pressure cylinder 3 outwardly.
• the low pressure and high pressure cylinders 2 and 3 are separated by an intermediate wall 7 provided with a central, through bore 7A for sealingly receiving an axially displaceable high pressure piston 13 firmly attached to a low pressure piston 12, as will be described more closely below with reference specifically to fig. 2.
• the low pressure cylinder 2 which is illustrated with a portion thereof cut away in figs. 1 and 2, is clamped between the rear end wall 4 and the intermediate wall 7 by means of first connecting rods 10, in the illustrated embodiment twelve rods evenly distributed around the outer circumference of the cylinder 2.
• the rods 10 are passed through bores (not shown) in the end wall 4 and their threaded front ends 10A are screwed into corresponding threaded blind bores (not shown) in the intermediate wall 7.
• the likewise threaded rear ends 10B of the rods 10 extend out through corresponding bores in the rear end wall 4 and are engaged by nuts 11 tightened against the end wall 4.
• the front end of the low pressure cylinder 2 is guided by a projection 7C formed by a step in the rear end face of the intermediate wall 7, and the rear end thereof is likewise guided by a projection 4A formed by a step in the front end face of the rear end wall 4.
• O-rings or equivalent seals are provided between the respective surfaces of the cylinder wall 2 and the projections 7C, 4A for providing a fluid seal therebetween.
• the low pressure cylinder 2 displaceably receives the low pressure piston 12 which is provided with the appropriate seals 12 A, such as O-rings, at its outer circumference for sealingly engaging the inner wall of the cylinder 2.
• the low pressure cylinder 2 is divided into a rear working chamber 18 and a front return chamber 17.
• Inlet-outlet openings 19, 20 for low pressure working fluid are provided in the rear wall 4 and in the intermediate wall 7, respectively and serve to supply working fluid to the working chamber 18 and return fluid to the return chamber 17, respectively.
• the low pressure piston 12 carries a high pressure piston 13 protruding from the front face thereof and extending into the central bore 7A of the intermediate wall 7.
• Said central bore 7A is provided with a low pressure seal 21 surrounding and sealingly engaging the high pressure piston 13 and positioned in the rear portion of the bore7A, closest to the low pressure cylinder 2.
• the low pressure seal 21 is a multi-lip seal of a synthetic composite material, but other standard seals suitable for the pressures on the low pressure side may likewise be employed.
• a distribution ring or bushing 22 In front of the low pressure seal 21, adjacent the latter, is positioned a distribution ring or bushing 22 containing radial inlet openings 22A (only one is illustrated), communicating with a low pressure fluid inlet 49, through which fluid is introduced into the high pressure cylinder 3, as will explained further below.
• a further bushing 23 In front of the distribution ring 22 is provided a further bushing 23 carrying a similar multi-lip seal 24 of a synthetic composite material, and serving as a final seal against a high pressure chamber 16.
• the high pressure chamber 16 is formed in the high pressure cylinder 3 and partly in the bore 7A in the intermediate wall 7, in front of the high pressure piston 13, and by a central bore 5 A in the front end wall 5.
• the high pressure piston 13 is firmly attached to the low pressure piston 12, and may preferably be secured with a press fit in a central opening provided in the low pressure piston.
• the piston 13 is provided with a central through bore 25 illustrated in greater detail in figs. 4A-B.
• the through bore 25 opens into the working fluid chamber 18 at one end and into the high pressure chamber 16 at the other end.
• the front end of the high pressure piston 13 is provided with a one way restrictor 26 having a displaceable valve cone 27 cooperating with a valve seat 30 provided in a valve body 29.
• the valve cone 27 is pressed against the seat 30 by a spring 29C acting between a spring retainer 29B and the valve cone, and the valve cone, the spring and spring retainer are maintained in position in the valve body 29 by a retainer ring in a conventional manner.
• the valve body 29 itself is locked in position in a recess in the end face of the piston 13 in a similar manner.
• valve cone 27 is provided with a narrow central restriction channel 28 through which a restricted fluid flow is permitted in the direction from the high pressure chamber 16 to the piston bore 25, even when the valve cone is seated against the seat 30.
• valve body 29 is also provided with a number of air discharge channels 29A (only one illustrated in figs. 4A-B) serving to discharge air from the radially outer parts of the high pressure chamber 16, as will be apparent.
• a check valve 31 similar to the one way restrictor 26, but lacking the restriction channel.
• the check valve 31 completely blocks fluid flow in the direction from the high pressure chamber 16 to the working fluid chamber 18 of the low pressure cylinder 2 when its displaceable valve cone 32 engages the valve seat 33 provided in the valve body 34.
• the valve cone 32 is lifted from the valve seat 33 by a valve operating rod 35.
• the valve operating rod 35 is secured to the front face of the rear wall 4 by means of a bolt 37 connected to a bushing 36 screwed into a recess provided in said front face of the rear wall 4.
• the rod 35 extends into the working chamber 18 and is aligned with the through bore 25 of the high pressure piston 13 and with the outlet opening in the valve body 34 so that it will open the check valve 31 to allow fluid flow from the high pressure chamber 16 to the working fluid chamber 18 during the mentioned operational phases.
• the rod 35 has an outer diameter that is slightly smaller than the inner diameter of the outlet opening in the valve body 34, to allow fluid flow from the through bore 25 to the working fluid chamber 18, past the outside of the rod 35.
• the front wall 5 of the high pressure cylinder 3 is provided with a central high pressure outlet 14 through which a high pressure fluid consumer (not shown) is connected to the portion of the high pressure chamber 16 formed by the bore 5 A within the front end wall 5.
• the front end wall 5 is provided with an adapter 6 for direct attachment to the consumer by means of bolts 6A.
• the outer end of the adapter 6 is provided with a bushing 6B carrying seals 6C; the indicated, ordinary O-rings will be sufficient in most cases, for providing an appropriate seal against the consumer as well as against the bushing 6B.
• Such an embodiment, where the apparatus 1 is "docked" directly in the consumer is preferred in many applications with very high pressures, such as in the hydroforming techniques, since it will eliminate the need for hose or pipe connections.
• the high pressure cylinder 3 is clamped between the front end wall 5 and the intermediate wall 7 by means of second, heavier connecting rods 8 evenly distributed around the outer periphery of the high pressure cylinder 3.
• eight connecting rods 8 are provided, the threaded rear ends 8B of which are screwed into corresponding threaded blind bores 7B provided in the front face of the intermediate wall 7 and the likewise threaded front ends 8A of which are extended through corresponding through bores 5B in the front end wall 5 and are engaged by nuts 15 tightened against the end wall 5.
• the connecting rods 8 carry at least one support ring 9 surrounding and provided in close engagement with the outer periphery of the high pressure cylinder 3. In figs.
• the high pressure cylinder 3 like the low pressure cylinder 2, is illustrated with a mid-portion thereof cut away, and it should be emphasized that one or more additional support rings 9 may be provided along the cut-away portion, the number of support rings 9 required depending i.a. upon the stroke length of the apparatus 1 and upon the strength of the wall of the high pressure cylinder 3.
• the high pressure cylinder 3 consists of separate, coaxial inner and outer casings 38 and 39 respectively.
• the inner casing 38 is provided closely fitting into the outer casing 39, and a pressure fluid space 40 is provided between the two casings, extending over a major portion of the axial length of the inner casing 38 and around the entire outer periphery thereof.
• the inner casing 38 of the high pressure cylinder 3 is provided with a high pressure seal assembly 43.
• the seal assembly 43 basically consists of a number of primary and secondary metal seal rings that are clamped between the front wall 5 and the intermediate wall 7, in the latter case through the bushings 22, 23, by means of the connecting rods 8.
• the metal seal rings are preferably manufactured from hardened steel, have a rectangular cross section and are formed with parallel circumferential grooves on their radially outer and inner surfaces. The purpose of said relief grooves is to perform an initial sealing between the high pressure cylinder and the high pressure piston, and to produce a pressure drop across each groove, thereby gradually reducing the fluid pressure.
• the secondary metal seal rings are provided with a recess in which a "soft seal" is received.
• the illustrated seal assembly 43 is disclosed in greater detail in our Swedish Patent Application No. 9904463-8 and the disclosure of said Patent Application is included herein by reference.
• Such a seal is specifically suitable for sealing against very high fluid pressures, such as those employed in the hydroforming techniques and in some press equipment and ranging from about 2000 bar upwards.
• the purpose of the double casing of the high pressure cylinder 3 as well as of the support ring 9 is to permit controlling the gap between the seal 43 and the high pressure piston, as is disclosed in detail in our Swedish Patent Application No. 9904464-
• the working stroke is initiated by introducing working fluid, normally the system fluid mentioned above, to the working chamber 18.
• working fluid normally the system fluid mentioned above
• the low pressure and high pressure pistons 12, 13 begin moving forward, i.e. to the left as seen in fig. 1.
• this initial forward movement does not cause any substantial increase in the high pressure cylinder 3 fluid pressure, since fluid is still discharged through the through bore 25 in the described manner, thereby equalizing the pressures in the high and low pressure cylinders 2, 3.
• the high pressure piston 13 blocks the fluid entering through the radial inlet openings 22A after a short forward movement. This represents an important improvement over the traditional, sensitive check valves normally used in high pressure side fluid inlets outside the apparatus.
• the check valve 31 blocks further discharge of fluid from the high pressure cylinder 3 through the through bore 25 and into the working chamber 18.
• the length of the rod 35 is adapted to the axial position of the high pressure seal 43 in the high pressure cylinder.
• the axial length of the part of the rod 35 protruding from the rear end wall 4 shall at least be equal to the axial distance between the front end of the high pressure piston 13 and the front end of the first (i.e. farthest to the left in fig. 2) metal ring of the high pressure seal 43, when the pistons 12, 13 are in their rearward position as illustrated in fig. 2. This means that the forward end of the high pressure piston 13 passes the first metal ring of the seal 43 before the rod 35 is disengaged from the valve 31.
• the pressure of the fluid in the high pressure chamber 16 will be multiplied, in the present embodiment approximately 20 times, corresponding to the ratio of the areas of the high and low pressure pistons. With the above given system pressure of 350 bar this will mean an output pressure in the order of 7000 bar. With pressures of this magnitude, and even higher, there is an immediate danger that "soft" seals would become damaged or even dislocated. Any such tendency is eliminated with the above discussed inventive proposals.
• a simplified pressure intensifier 100 suitable for applications requiring pressure fluid in lower pressure ranges of up to approximately 2000 bar, such as for pressurizing the space 40 between the casings 38, 39 of the high pressure cylinder
• the pressure intensifier 100 consists of a low pressure cylinder 102 with fluid inlets 119, 120 and a high pressure cylinder 103 with a fluid inlet 149 and a fluid outlet 114.
• the cylinders are provided with rear and front end walls 104 and 105 respectively.
• connecting rods 110 are in this case employed to clamp the low pressure cylinder 102 between the rear wall
• the front wall 105 is attached to the high pressure cylinder by means of bolts 108.
• a low pressure piston 112 is slidable in the low pressure cylinder 102 dividing it into a working chamber 118 and a return chamber 117.
• a high pressure piston 113 is fixed to the low pressure piston 112, extending into a high pressure chamber 116 in the high pressure cylinder 103.
• the high pressure piston 113 is provided with a central bore 125 opening into the working chamber 118 and the high pressure chamber 116.
• the bore 125 is provided with the front one way restrictor 126 and the rear check valve 31 with its valve cone 32 being engaged and moved by the rod 135.
• the simplified pressure intensifier 100 is provided with a high pressure seal 143 being a multiple lip seal like the low pressure seal 121.
• the high pressure side is initially flushed by fluid of system pressure supplied through the fluid inlet 149, in a position immediately in front of the high pressure piston 113.
• the valves 126 and 131 in the bore 125 of the high pressure piston 113 the high pressure seal 143 is once more protected from the high output pressure, until supported by the piston 113.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Actuator (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
• Fluid-Pressure Circuits (AREA)
• Gripping On Spindles (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (6)

Cited By (2)

Citations (2)

• 1999
  • 1999-12-07 SE SE9904464A patent/SE9904464D0/sv unknown
• 2000
  • 2000-11-29 AU AU20343/01A patent/AU2034301A/en not_active Abandoned
  • 2000-11-29 WO PCT/SE2000/002366 patent/WO2001042662A1/en active IP Right Grant
  • 2000-11-29 EP EP00983611A patent/EP1242746B1/en not_active Expired - Lifetime
  • 2000-11-29 DE DE60013324T patent/DE60013324T2/de not_active Expired - Lifetime
  • 2000-11-29 AT AT00983611T patent/ATE274645T1/de not_active IP Right Cessation

Patent Citations (2)

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