Classifications

• • 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
  • F04B7/00—Piston machines or pumps characterised by having positively-driven valving
  • F04B7/04—Piston machines or pumps characterised by having positively-driven valving in which the valving is performed by pistons and cylinders coacting to open and close intake or outlet ports
• • 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
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
  • F04B1/0404—Details or component parts
  • F04B1/0426—Arrangements for pressing the pistons against the actuated cam; Arrangements for connecting the pistons to the actuated cam
• • 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
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
  • F04B1/06—Control
  • F04B1/063—Control by using a valve in a system with several pumping chambers wherein the flow-path through the chambers can be changed, e.g. between series and parallel flow
• • 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
  • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
  • F04B49/02—Stopping, starting, unloading or idling control
  • F04B49/022—Stopping, starting, unloading or idling control by means of pressure

Definitions

• the invention relates to a piston pump according to the preamble of claim 1.
• Pressure medium pumps are required for the supply of pressure medium to actuating and lubricating hydraulic systems of continuously variable transmissions or automatic transmissions. Such hydraulic systems have to work safely and quickly when the engine is idling. This requires a large pump with small leakage losses. However, at the final engine speed, such a pump delivers a great deal of oil which is not required in this operating range. This makes the control of the transmission large and complex. At high speeds, there are high power losses over longer periods in which no gear changes are made.
• the invention has for its object to provide a pressure medium supply device for the actuating and lubricating hydraulics of gearboxes or other units, with which a large amount of pressure medium can be made available after a short response time. In the periods in which no actuating movements or switching operations are carried out, there should be no or only minimal power losses. This object is achieved by the features specified in claim 1. Appropriate and advantageous refinements are contained in the subclaims.
• a piston pump with the features of the preamble of claim 1 is proposed in the earlier patent application P 33 34 697.6-15. When used as a secondary pump, this pump is intended to ensure a reliable oil supply for the lubrication and cooling circuits of transmissions in the event of a failure of the primary pump. The power losses in this pump should also be kept small.
• the intake line of the pistons is shut off by the control valve.
• the design of the control valve according to the invention makes it possible to shut off or open the suction lines individually - or also in groups - so that the number of cylinder-piston units required to maintain the required working pressure is promoted. Due to the differently preloaded closing springs of the inlet check valves of the various cylinder-piston units, the pistons can be pressed onto the lifting element in a certain order. This allows the pulsation to be reduced to a low value.
• the filling pressure can be generated by any conveyor.
• a cylinder-piston unit the piston of which is held, for example, by a spring in contact with the lifting element, is used to generate the control pressure.
• one cylinder-piston unit after the other is activated via the pressure relief valve and the control valve switched off.
• Fig. 1 is a schematic representation of the piston pump
• Fig. 2 shows a second embodiment of the piston pump.
• the piston pump which is shown in the drawing as a radial piston pump, but can also be an axial piston pump, has a plurality of cylinder-piston units 1, 2, 3, 4, 5, the pistons 6 of which can be driven by a lifting element 7.
• the lifting element 7 is arranged, for example, in the form of an eccentric on an eccentric shaft 8.
• Each cylinder-piston unit 1, 2, 3, 4, 5 has an inlet check valve 9 which is connected to an intake line 10. ''
• each cylinder-piston unit has an exhaust return Impact valve 11, which via a collecting pressure line 12 which is connected to a pressure medium circuit with an integrated consumer 13.
• the consumer 13 is formed, for example, by actuating or switching devices of an automatic transmission and contains known control, actuating and switching elements, so that a detailed representation of the consumer is not necessary.
• the collecting pressure line 12 can also be divided between several consumers.
• the pistons 6 of the cylinder-piston units 1, 2, 3, 4, 5 are not pressed onto the lifting element 7 by mechanical pressing means, such as, for example, compression springs or retaining clips. Rather, the pistons 6 can only be pressed against the lifting element 7 by a specific filling or control pressure.
• the filling pressure can be generated by any pressure source, such as a small internal gear pump rotating with the eccentric shaft 8 or a memory of a separate pressure medium circuit.
• the control pressure is generated by a cylinder-piston unit 14, the piston 15 of which is held in contact with the lifting element 7 by a pressure spring 16.
• the cylinder-piston unit sucks pressure medium from a container 18 via an inlet check valve 17 and delivers it via an outlet check valve 19 into the collecting pressure line 12.
• the pressure medium delivered by the cylinder-piston unit 14 flows back into the line 10 via the control valve of the consumer 13, not shown. If the pressure in line 10 and thus also in line 10.1 rises to a value the level of which corresponds to a control pressure defined by a closing spring 20 of inlet check valve 9, inlet check valve 9 opens and piston 6 comes into contact with the system the lifting element 7 is pressed. The cylinder-piston unit 1 thus begins to deliver.
• the closing springs 20 of the inlet check valves 9 of the individual cylinder-piston units 1, 2, 3, 4, 5 expediently have different preloads in order to achieve an adaptation of the delivered pressure medium flow to the pressure medium flow required by the consumer 13.
• the preloads of the individual closing springs 20 are selected such that the pistons 6 of the individual cylinder-piston units are pressed onto the lifting element 7 one after the other in a specific sequence.
• the pistons 6 are pressed, for example, in the order in which the cylinder-piston units 1, 2, 3, 4, 5 are numbered in FIG. 1. As a result, the pulsation of the respective total pressure medium flow is reduced to a minimum value.
• a control valve 21 is arranged between the consumer 13 and the inlet check valves 9.
• a control slide 22 of the control valve 21 is designed as a differential piston, which has a small piston collar 23 with a small piston surface 24 and a large piston collar 25 with a large piston surface 26.
• the small piston surface 24 delimits a valve chamber 27 on one side.
• a compression spring 28 is arranged in the valve chamber 27 and acts on the control slide 22.
• Control grooves 29, 30, 31, 32, 33, the number of pistons 6 of the cylinder-piston units 1, 2, 3, 4 which can be pressed against the lifting element 7 by the control pressure, are arranged in the essentially cylindrical valve chamber 27 , 5 corresponds.
• the suction line 10 is connected to the valve chamber 27.
• Sub-lines 10.1, 10.2, 10.3, 10.4, 10.5 of the intake line 10 are connected to the control grooves 29, 30, 31, 32, 33 and connect them to the inlet check valves 9 of the cylinder-piston units 1, 2, 3, 4, 5.
• a pressure relief valve 34 is connected to the suction line 10 between the consumer 13 and the control valve 21.
• the pressure limiting valve 34 In its neutral position, which can be set by a spring 35, the pressure limiting valve 34 establishes a connection a piston chamber 36 adjoining the large piston surface 26 of the control valve 21 via a control line 37 to the container 18.
• the pressure limiting valve 34 In its switching position shifted from the neutral position, the pressure limiting valve 34 connects the suction line 10 via the control line 37 the piston chamber 36. In this switching position, the connection from the piston chamber 36 via the control line 37 to the container 18 is blocked.
• a further, spring-loaded pressure relief valve 38 is also connected to the suction line 10, via which a connection from the suction line 10 to the container 18 can be established.
• the cylinder-piston unit 14 sucks pressure medium from the container 18 via its inlet check valve 17 and conveys it via the outlet check valve 19 into the collecting pressure line 12 If the consumer 13 does not need any pressurized pressure medium, the delivery flow of the cylinder-piston unit 14 flows into the line 10. The pressure in the suction line 10 increases until it reaches the value of the filling pressure (eg 5 bar) . As a result, the inlet check valves 9 open, the pistons 6 are pressed against the lifting element 7 and the cylinder-piston units 1, 2, 3, 4, 5 begin to deliver.
• the filling pressure eg 5 bar
• the pressure in the intake line 10 continues to increase until it reaches the value of the response pressure (eg 6 bar) of the pressure relief valve 34.
• the control slide 22 is shifted to the left in FIG. 1 and the channels 33, 32, 31, 30 and 29 closed.
• the pressure medium supply to the inlet check valves 9 is interrupted and the pistons 6 of the cylinder-piston units 1, 2, 3, 4, 5 lift off the lifting element 7.
• the delivery rate of the pump decreases until only the delivery volume of the cylinder-piston unit 14 remains. If the pressure continues to rise, the pressure-limiting valve 38 is opened, for example, at a pressure of 7 bar, and the pressure medium flows into the container 18.
• the pressure in the intake line 10 increases until the pressure limiting valve 34 is opened and establishes a connection between the intake line 10 and the piston chamber 36 Due to the pressure acting on the large piston surface 26, the control slide 22 is displaced to the left against the force of the compression spring 28 in FIG. 1 and blocks the control grooves 33, 32, 31, 30, 29 and thereby the inflow of pressure medium, the Pressure is above the control pressure that enables the delivery of the cylinder-piston units. As a result, the cylinder-piston units 1, 2, 3, 4, 5 are switched off in an order that the Order of connection is opposite.
• the power losses of the piston pump according to the invention can be further reduced. This is possible because the piston 15 of the cylinder-piston unit 14, which serves to generate the control pressure in the embodiment of FIG. 1, is also designed to be liftable from the lifting element.
• FIG. 2 shows an embodiment in which a piston 39 of the cylinder-piston unit 40 can be lifted off the lifting element 7 by the pressure in a control line 41.
• the control line 41 transmits the pressure generated by the further pressure source, not shown, to an axial surface 42 of the piston 39.
• the cylinder pressure can also be generated by the pressure generated by the further pressure source and also available to the consumer 13.
• Piston unit 40 are switched off. Only when the other pressure source fails does the piston 39 come into contact with the lifting element 7 by a compression spring 43. The cylinder-piston unit 40 then takes over the function of a device for generating a control pressure.
• Reference numerals Reference numerals

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Details Of Reciprocating Pumps (AREA)
• Control Of Positive-Displacement Pumps (AREA)
• Reciprocating Pumps (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8164935

Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (3)

Citations (4)

• 1985
  • 1985-03-23 BR BR8507174A patent/BR8507174A/pt unknown
  • 1985-03-23 WO PCT/EP1985/000125 patent/WO1985004690A1/de active IP Right Grant
  • 1985-03-23 DE DE19853510633 patent/DE3510633A1/de not_active Withdrawn
  • 1985-03-23 EP EP85902004A patent/EP0208692B1/de not_active Expired
  • 1985-03-23 DE DE19853564312 patent/DE3564312D1/de not_active Expired
  • 1985-12-03 KR KR1019850700360A patent/KR860700052A/ko not_active Withdrawn

Patent Citations (4)

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