US3885393A - Hydraulic load matching device - Google Patents

Hydraulic load matching device Download PDF

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Publication number
US3885393A
US3885393A US395219A US39521973A US3885393A US 3885393 A US3885393 A US 3885393A US 395219 A US395219 A US 395219A US 39521973 A US39521973 A US 39521973A US 3885393 A US3885393 A US 3885393A
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United States
Prior art keywords
piston
engine
cylinder
diffuser
matching device
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Expired - Lifetime
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US395219A
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John P Hanson
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US Department of Energy
Energy Research and Development Administration ERDA
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US Department of Energy
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Priority to US395219A priority Critical patent/US3885393A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B9/00—Piston machines or pumps characterised by the driving or driven means to or from their working members
    • F04B9/08—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid
    • F04B9/10—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid the fluid being liquid
    • F04B9/103—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid the fluid being liquid having only one pumping chamber
    • F04B9/107—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid the fluid being liquid having only one pumping chamber rectilinear movement of the pumping member in the working direction being obtained by a single-acting liquid motor, e.g. actuated in the other direction by gravity or a spring
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
    • A61M60/10—Location thereof with respect to the patient's body
    • A61M60/122—Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body
    • A61M60/196—Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body replacing the entire heart, e.g. total artificial hearts [TAH]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
    • A61M60/40—Details relating to driving
    • A61M60/424—Details relating to driving for positive displacement blood pumps
    • A61M60/427—Details relating to driving for positive displacement blood pumps the force acting on the blood contacting member being hydraulic or pneumatic
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
    • A61M60/80—Constructional details other than related to driving
    • A61M60/855—Constructional details other than related to driving of implantable pumps or pumping devices
    • A61M60/857—Implantable blood tubes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
    • A61M60/80—Constructional details other than related to driving
    • A61M60/855—Constructional details other than related to driving of implantable pumps or pumping devices
    • A61M60/89—Valves
    • A61M60/892—Active valves, i.e. actuated by an external force

Definitions

  • thermodynamic engine cylin- The matchlng is accomplished hydrauhcally and allows for UNITED STATES PATENTS interruption of the engine cycle periodically for con- 777,008 l2/l904 Defies et al 60/593 [r0] purposes. 2,490,118 l2/l949 Dickinson 4l7/383 3,044,267 7/1962 Hicks 60/533 3 Claims, 2 Drawing Figures v 20 12 15 17 1s 4 l 14 as F f 2 22 r V 11 '7 i 25 PATENTEDMAY 2 7 I975 SHEET N MI: 228% ust m5 8 Q0 3 to 8 N6 3 o I I o SEZE MSBG m o5 5 T BEmS mxomhm 4 5m mo .zmom um HYDRAULIC LOAD MATCHING DEVICE BACKGROUND OF THE INVENTION DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, a
  • a heart pump which may be implanted in a human body for replacement of the natural heart.
  • the need in artificial hearts is for a simple, compact, lightweight, reliable, low energy requirement pump having the capability of closely approximating the pumping ability of the normal human heart.
  • the pump must correspond functionally as nearly as possible with the natural heart.
  • the load matching device of the present invention is designed to couple the output of a thermodynamic engine to a load such as a blood pump.
  • a load such as a blood pump.
  • the working fluid of a thermodynamic engine must be allowed to expand during a portion of the power stroke. As this occurs, the pressure within the cylinder drops. For this reason, the force developed by the piston varies through the power stroke. For most applications, the load does not match this force variation, and some means must be found of storing the en ergy during the first portion of the stroke and releasing it during the later low pressure portions of the stroke.
  • the blood pump is allowed to fill at a rate determined by the venous blood pressure.
  • the engine is triggered, emptying the accumulated blood into the aorta.
  • the pump discharge pressure is essentially constant over the power discharge stroke, a mis-match exists between the prime mover force/displacement characteristics and the force/displacement characteristics of the blood.
  • the device consists of a liquid filled tube joining a master and slave piston and cylinder.
  • FIG. 1 is a view showing the structure of the hydraulic load matching device.
  • FIG. 2 shows a typical displacement/time curve for hydraulic load matching device as applied to a blood pump.
  • Piston I3 is enclosed within an master cylinder 16, which is the first stage in the load matching device of the present invention.
  • the force transmitted from the engine to the master cylinder I6 forces fluid through a nozzle 17 and then into a transmission tube [8. Part of the input force is transmitted hydrostatically through a diffuser 19 to slave cylinder 20, causing the piston 2]. contained within the slave cylinder 20, to move linearly. Any excess force provided at the master cylinder appears as a positive pressure difference between the master and slave cylinder. The pressure difference accelerates the liquid in the transmission tube. providing energy storage in the liquid in the form of kinetic energy. When the force on the master cylinder falls below that needed to move the load at a steady rate, the liquid decelerates. converting the kinetic energy of the moving fluid into a negative pressure difference, and allow ing the load to keep moving.
  • FIG. 2 presents a typical displacement/time curve for a system using the load matching device of the subject invention.
  • the timing has been arbitrarily set at 0.2 seconds for the systole (pumping) part of the stroke and 0.3 seconds for the diastole (return) part ofthe stroke.
  • the load could be a blood pump 22.
  • the inlet valve 23 of the pump is closed while the output valve 24 is open and the pressure in the slave cylinder 20 is proportional to the arterial pressure during systole.
  • This pressure varies from approximately mm Hg to approximately I20 mm Hg during the stroke.
  • the actual pressure would depend on the area ratio between the slave cylinder piston 21 and that of the blood pump 22.
  • the pump body is connected to the veins, and the pressure is essentially zero.
  • the pump body could be fitted with a flexible dome 25 to prevent the return spring from collapsing the veins during diastole.
  • the actual size of the transmission tube 18 will depend on the area ratio between the slave cylinder 20 and the pump diaphragm, as well as the working fluid selected. In addition, the engine expansion ratio and the desired timing will affect the dimensions of the device. Using the timing shown in FIG. 2, with a lzl area ratio between slave cylinder and pump diaphragm, the displacement volume should be approximately cc to provide 12 liters/minute of blood flow. Using water as the transmission fluid, the length of the tube should be about 3 feet with a diameter of about inch in order to obtain the performance shown in FIG. 2. This is perhaps longer than needed to connect a typical engine and pump, but the excess length could be coiled around the engine housing with little loss in performance. The dimensions of the master and slave cylinders can be varied to suit the installation as long as the displaced volume is kept constant.
  • a device for matching load characteristics to engine characteristics comprising:
  • cylindrical transmission tube at the converging end of said nozzle
  • slave cylinder connected to said diffuser at the divergent end of said diffuser

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  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Cardiology (AREA)
  • Mechanical Engineering (AREA)
  • Biomedical Technology (AREA)
  • Anesthesiology (AREA)
  • Hematology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • General Engineering & Computer Science (AREA)
  • External Artificial Organs (AREA)

Abstract

The invention consists of a device for use in an artificial heart which efficiently matches the force/displacement characteristics of a thermodynamic engine to the force/displacement characteristics of the blood. The matching is accomplished hydraulically and allows for interruption of the engine cycle periodically for control purposes.

Description

United States Patent Hanson 1 May 27, 1975 [54] HYDRAULIC LOAD MATCHING DEVICE 3,080,820 3/1963 Browne 417/383 3,257,8[0 6 1966 H 60 547 [75] Inventor: John P. Hanson, McKeesport, Pa. mm [73] Assignee: The United States of America as FOREIGN PATENTS 0R APPLICATIONS represented he United Sates Franc: A t r r t i .4 Energy Research and Development Administration, Washington, DC. Primary Examiner-Martin P. Schwadron [22] Filed: Sem 7 1973 Assistant Examiner-H. Burks, Sr.
Appl. No: 395,219
Attorney. Agent, or Firm-Dean E. Carlson; Robert J. Marchick [S2] U.S. Cl .3 60/583; 4l7/383 [57] ABSTRACT [51] Int. Cl. ..F15b 7/00 Th t f d f 581 Field of Search 3. 60/537, 547, 583, 593, e F 3 1a] heart which efficiently matches the forceldisplace- 60/533, 585, 417/383 ment charactensncs of a thermodynamic engine to the [56] Rererences Cited force/displacement characteristics of the blood. The matchlng is accomplished hydrauhcally and allows for UNITED STATES PATENTS interruption of the engine cycle periodically for con- 777,008 l2/l904 Defies et al 60/593 [r0] purposes. 2,490,118 l2/l949 Dickinson 4l7/383 3,044,267 7/1962 Hicks 60/533 3 Claims, 2 Drawing Figures v 20 12 15 17 1s 4 l 14 as F f 2 22 r V 11 '7 i 25 PATENTEDMAY 2 7 I975 SHEET N MI: 228% ust m5 8 Q0 3 to 8 N6 3 o I I o SEZE MSBG m o5 5 T BEmS mxomhm 4 5m mo .zmom um HYDRAULIC LOAD MATCHING DEVICE BACKGROUND OF THE INVENTION DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, a thermodynamic engine cylin- The imention relates to a load matching device use' 5 der ll contains a piston I2 which drives a piston I3,
ful in a heart pump which may be implanted in a human body for replacement of the natural heart. The need in artificial hearts is for a simple, compact, lightweight, reliable, low energy requirement pump having the capability of closely approximating the pumping ability of the normal human heart. The pump must correspond functionally as nearly as possible with the natural heart.
The load matching device of the present invention is designed to couple the output of a thermodynamic engine to a load such as a blood pump. For best efficiency, the working fluid of a thermodynamic engine must be allowed to expand during a portion of the power stroke. As this occurs, the pressure within the cylinder drops. For this reason, the force developed by the piston varies through the power stroke. For most applications, the load does not match this force variation, and some means must be found of storing the en ergy during the first portion of the stroke and releasing it during the later low pressure portions of the stroke. For most application, where the speed is not expected to vary significantly from stroke to stroke, this is accomplished by converting the reciprocating motion of the piston to rotary motion, thus allowing the excess energy to be stored as a small increase in the angular velocity of a flywheel. However, there are applications where the engine must come to a complete stop at the end of each stroke, and the use ofa flywheel to match the engine characteristics to the load characteristics would not be convenient.
One exampie of an application where the use of a flywheel for force matching between the prime mover and the load is inconvenient is the so called heart rate artificial heart. In such a device, the blood pump is allowed to fill at a rate determined by the venous blood pressure. When the blood pump fills completely, the engine is triggered, emptying the accumulated blood into the aorta. As the pump discharge pressure is essentially constant over the power discharge stroke, a mis-match exists between the prime mover force/displacement characteristics and the force/displacement characteristics of the blood.
SUMMARY OF THE INVENTION Accordingly. it is an object of the present invention to provide an improved fluid flow apparatus which smooths a varying fluid stream.
It is a further object ofthe invention to provide an apparatus for hydraulically matching the force/displacement characteristics of the blood. without the use of valves or accumulators, and without the need for rotating masses or bearings. The device consists of a liquid filled tube joining a master and slave piston and cylinder.
The invention will be best understood with reference to the following specification taken in conjunction with the accompanying drawings, of which:
FIG. 1 is a view showing the structure of the hydraulic load matching device.
FIG. 2 shows a typical displacement/time curve for hydraulic load matching device as applied to a blood pump.
the pistons being connected by a shaft 14. A return spring 15 is located within engine cylinder II around shaft [4 in order to improve piston return timing. Piston I3 is enclosed within an master cylinder 16, which is the first stage in the load matching device of the present invention.
In operation, the force transmitted from the engine to the master cylinder I6 forces fluid through a nozzle 17 and then into a transmission tube [8. Part of the input force is transmitted hydrostatically through a diffuser 19 to slave cylinder 20, causing the piston 2]. contained within the slave cylinder 20, to move linearly. Any excess force provided at the master cylinder appears as a positive pressure difference between the master and slave cylinder. The pressure difference accelerates the liquid in the transmission tube. providing energy storage in the liquid in the form of kinetic energy. When the force on the master cylinder falls below that needed to move the load at a steady rate, the liquid decelerates. converting the kinetic energy of the moving fluid into a negative pressure difference, and allow ing the load to keep moving.
FIG. 2 presents a typical displacement/time curve for a system using the load matching device of the subject invention. The timing has been arbitrarily set at 0.2 seconds for the systole (pumping) part of the stroke and 0.3 seconds for the diastole (return) part ofthe stroke.
In operation, the load could be a blood pump 22. In this case, the inlet valve 23 of the pump is closed while the output valve 24 is open and the pressure in the slave cylinder 20 is proportional to the arterial pressure during systole. This pressure varies from approximately mm Hg to approximately I20 mm Hg during the stroke. The actual pressure would depend on the area ratio between the slave cylinder piston 21 and that of the blood pump 22. During diastole, the pump body is connected to the veins, and the pressure is essentially zero. The pump body could be fitted with a flexible dome 25 to prevent the return spring from collapsing the veins during diastole.
The actual size of the transmission tube 18 will depend on the area ratio between the slave cylinder 20 and the pump diaphragm, as well as the working fluid selected. In addition, the engine expansion ratio and the desired timing will affect the dimensions of the device. Using the timing shown in FIG. 2, with a lzl area ratio between slave cylinder and pump diaphragm, the displacement volume should be approximately cc to provide 12 liters/minute of blood flow. Using water as the transmission fluid, the length of the tube should be about 3 feet with a diameter of about inch in order to obtain the performance shown in FIG. 2. This is perhaps longer than needed to connect a typical engine and pump, but the excess length could be coiled around the engine housing with little loss in performance. The dimensions of the master and slave cylinders can be varied to suit the installation as long as the displaced volume is kept constant.
What is claimed is:
l. A device for matching load characteristics to engine characteristics comprising:
an input shaft from an associated engine cylinder;
first piston at the end of said shaft;
master cylinder containing said shaft and said piston:
nozzle at one end of said master cylinder; cylindrical transmission tube at the converging end of said nozzle;
conical diffuser at the opposite end of said transmission tube;
slave cylinder connected to said diffuser at the divergent end of said diffuser;
second piston contained within said slave cylinder;

Claims (3)

1. A device for matching load characteristics to engine characteristics comprising: an input shaft from an associated engine cylinder; a first piston at the end of said shaft; a master cylinder containing said shaft and said piston; a nozzle at one end of said master cylinder; a cylindrical transmission tube at the converging end of said nozzle; a conical diffuser at the opposite end of said transmission tube; a slave cylinder connected to said diffuser at the divergent end of said diffuser; a second piston contaiNed within said slave cylinder; and an incompressible fluid contained within said master cylinder, said nozzle, said transmission tube, said diffuser, and said slave cylinder for transmission of motion between said first piston and second piston.
2. The device of claim 1 wherein said transmission tube is of a diameter of 1/2 inch.
3. The device of claim 2 wherein said incompressible fluid is water.
US395219A 1973-09-07 1973-09-07 Hydraulic load matching device Expired - Lifetime US3885393A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4488853A (en) * 1980-08-28 1984-12-18 New Process Industries, Inc. Fluid pressure ratio transformer system
US5062268A (en) * 1990-02-02 1991-11-05 The University Of British Columbia Fluid actuator
WO2007147914A1 (en) * 2006-06-13 2007-12-27 Prextor Systems, S.L. Split-chamber pressure exchangers
ES2321999A1 (en) * 2006-06-13 2009-06-15 Fernando Ruiz del Olmo Split-chamber pressure exchangers
CN101862480A (en) * 2010-07-19 2010-10-20 刘晓程 Cardiac auxiliary volume amplifier

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US777008A (en) * 1903-12-21 1904-12-06 E Tablissements De L Horme Et De La Buire Soc Nouv Multiplier for hydraulic presses.
US2490118A (en) * 1945-07-23 1949-12-06 Hygroequipments Ltd Pump
US3044267A (en) * 1960-01-07 1962-07-17 James M Hicks Throttle control
US3080820A (en) * 1958-12-19 1963-03-12 Scott & Williams Inc Pumping system
US3257810A (en) * 1963-09-12 1966-06-28 Hanni Eduard Hydraulic drive system for press brakes

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US777008A (en) * 1903-12-21 1904-12-06 E Tablissements De L Horme Et De La Buire Soc Nouv Multiplier for hydraulic presses.
US2490118A (en) * 1945-07-23 1949-12-06 Hygroequipments Ltd Pump
US3080820A (en) * 1958-12-19 1963-03-12 Scott & Williams Inc Pumping system
US3044267A (en) * 1960-01-07 1962-07-17 James M Hicks Throttle control
US3257810A (en) * 1963-09-12 1966-06-28 Hanni Eduard Hydraulic drive system for press brakes

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4488853A (en) * 1980-08-28 1984-12-18 New Process Industries, Inc. Fluid pressure ratio transformer system
US5062268A (en) * 1990-02-02 1991-11-05 The University Of British Columbia Fluid actuator
WO2007147914A1 (en) * 2006-06-13 2007-12-27 Prextor Systems, S.L. Split-chamber pressure exchangers
ES2321999A1 (en) * 2006-06-13 2009-06-15 Fernando Ruiz del Olmo Split-chamber pressure exchangers
ES2321997A1 (en) * 2006-06-13 2009-06-15 Fernando Ruiz del Olmo Split-chamber pressure exchangers
US20100014997A1 (en) * 2006-06-13 2010-01-21 Ruiz Del Olmo Fernando Split-chamber pressure exchangers
ES2321999B1 (en) * 2006-06-13 2010-03-03 Fernando Ruiz del Olmo PRESSURE EXCHANGERS OF MULTIETAPA DEVELOPED CAMERAS.
ES2321997B1 (en) * 2006-06-13 2010-03-03 Fernando Ruiz del Olmo PRESSURE EXCHANGERS OF DEVELOPED BEDS.
CN101862480A (en) * 2010-07-19 2010-10-20 刘晓程 Cardiac auxiliary volume amplifier
CN101862480B (en) * 2010-07-19 2012-06-13 刘晓程 Cardiac auxiliary volume amplifier

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