EP2022985A2 - Zahnradpumpe mit variabler Verdrängung - Google Patents

Zahnradpumpe mit variabler Verdrängung Download PDF

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Publication number
EP2022985A2
EP2022985A2 EP08014138A EP08014138A EP2022985A2 EP 2022985 A2 EP2022985 A2 EP 2022985A2 EP 08014138 A EP08014138 A EP 08014138A EP 08014138 A EP08014138 A EP 08014138A EP 2022985 A2 EP2022985 A2 EP 2022985A2
Authority
EP
European Patent Office
Prior art keywords
passage
suction
discharge
gear pump
gear
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08014138A
Other languages
English (en)
French (fr)
Inventor
Hironao Yokoi
Shigeru Suzuki
Katsumi Yamashita
Toshiro Fujii
Masaki Ota
Kazuo Murakami
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyota Industries Corp
Original Assignee
Toyota Industries Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2008030926A external-priority patent/JP2009062970A/ja
Application filed by Toyota Industries Corp filed Critical Toyota Industries Corp
Publication of EP2022985A2 publication Critical patent/EP2022985A2/de
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C11/00—Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations
    • F04C11/001—Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations of similar working principle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
    • F04C14/06—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations specially adapted for stopping, starting, idling or no-load operation
    • F04C14/065—Capacity control using a multiplicity of units or pumping capacities, e.g. multiple chambers, individually switchable or controllable
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
    • F04C14/24—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves
    • F04C14/26—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves using bypass channels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/082—Details specially related to intermeshing engagement type machines or pumps
    • F04C2/086—Carter
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/12—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
    • F04C2/14—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
    • F04C2/18—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with similar tooth forms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2240/00—Components
    • F04C2240/30—Casings or housings

Definitions

  • the present invention relates to a variable displacement type gear pump.
  • the variable displacement type gear pump has plural gear mechanisms including a drive gear and a driven gear, and the plural gear mechanisms are accommodated in plural gear chambers which are independently formed.
  • a gear pump includes a gear mechanism having a drive gear and a driven gear therein.
  • the gear pump introduces fluid from the outside, pressurizes the fluid through a gear mechanism, and discharges the fluid to the outside.
  • hydraulic oil is utilized as the fluid for the gear pump
  • the gear pump is capable of operating a hydraulic equipment located in a hydraulic circuit.
  • the gear pump has a simple structure, compared to other type pumps. Therefore, the operation and the maintenance are easily performed, and further, the manufacturing cost is low.
  • the gear pump is not easily affected by foreign matters in the fluid.
  • the gear pump is appropriate for downsizing and reducing weight.
  • the gear pump is utilized, for example, as a hydraulic pump in an industrial vehicle such as a forklift truck, and is operated by a combustion engine for running the industrial vehicle.
  • the discharge flow rate of the gear pump is determined in accordance with the rotational speed of the gear pump, and it is difficult to change the flow rate irrespective to the rotational speed.
  • the gear pump When the gear pump is operated more than demands, the gear pump generates excessive flow rate, and performs excessive work as a gear pump.
  • a variable displacement type gear pump with plural gear mechanisms has been proposed for achieving discharge displacement.
  • the variable displacement type gear pump is shifted between two states. That is, in one state, a specific gear mechanism in the plural gear mechanisms discharges pressurized fluid to the outside, and in other state, the fluid is returned from the specific gear mechanism to the suction side, thereby achieving the discharge displacement.
  • Japanese Unexamined Patent Publication No. 2002-70757 discloses a double gear pump as a variable displacement type gear pump.
  • a drive gear and two driven gears engaging with the drive gear are accommodated in a casing, and function as first and second pumps.
  • An inlet and an outlet of the second gear pump are connected through an unload passage.
  • An electromagnetic valve is provided in the unload passage. When the electromagnetic valve is closed, the first pump and the second pump are operated in parallel, thereby increasing the discharge displacement. In this state, the gear pump is in large displacement operational state. When the electromagnetic valve is opened, the second pump is unloaded, thereby decreasing the discharge displacement. In this state, the gear pump is in small displacement operational state.
  • variable displacement gear pump the first pump and the second pump are located parallely.
  • the inlet and the outlet of the first pump are located reversely to the inlet and the outlet of the second pump, due to the rotational direction of the drive shaft. That is, the inlet of the first pump and the outlet of the second pump are located at one side of the drive shaft, and the outlet of the first pump and the inlet of the second pump are located at the other side.
  • a suction passage and a discharge passage are formed by connecting fluid passages at the inlet side and the outlet side of the first and the second pumps.
  • variable displacement type gear pump as disclosed in the above reference, the inlet and the outlet of the first pump are located reversely to the inlet and the outlet of the second pump.
  • the structure is complicated if the pump body includes therein the suction and discharge passages formed by connecting the fluid passages at the inlet side and the outlet side. It is also difficult to form such a pump body with the complicated passages.
  • this kind of variable displacement gear pump increases the size of the whole equipment, since the unload passage is located outside the gear pump for returning the fluid from the second pump to the inlet. Further, the fluid in the unload passage is divided into the first the second pumps, and joins the flow delivered from the inlet of the gear pump at the outlet of each pump so as to be discharged from each outlet, when small displacement operation is continued.
  • the fluid flowing through the unload passage continuously circulates through a specific part in the body of the gear pump, due to the continuation of the small displacement operation. That may cause a problem that the temperature distribution is uneven in the housing of the gear pump.
  • the unevenness of the temperature distribution in the housing may result in deforming the housing and decreasing the operational efficiency of the gear pump.
  • the present invention is directed to provide a variable displacement type gear pump that has a suction passage by connecting passages at the suction side in a housing, and that prevents specific fluid from continuously circulating in a specific passage in a gear pump body, even if continuing small displacement operation.
  • a variable displacement type gear pump introduces and discharges fluid.
  • the gear pump includes a housing, plural gear chambers having a gear mechanism, a suction-side space, and a discharge-side space.
  • the plural gear chambers are formed in the housing, one of which is a specific gear chamber.
  • the gear mechanism is accommodated in the respective gear chamber.
  • the suction-side space is formed in the respective gear chamber.
  • the discharge-side space is formed in the respective gear chamber.
  • the gear pump further includes a suction passage, an outlet passage, a return passage, an opening and closing valve, and a check valve.
  • the suction passage is formed in the housing so as to communicate with the suction-side spaces.
  • the outlet passage communicates with the discharge-side spaces.
  • the return passage returns the fluid discharged to the discharge-side space of the specific gear chamber to the suction passage.
  • the return passage communicates with the suction passage at a confluence portion located upstream side of the suction-side space.
  • the opening and closing valve is provided in the return passage, and opens the return passage in a small displacement operational state.
  • the check valve is located between the discharge-side space of the specific gear chamber and the outlet passage for preventing the fluid discharged from the gear chamber other than the specific gear chamber from flowing into the discharge-side space of the specific gear chamber in the small displacement operational state.
  • Fig. 1 shows a variable displacement type gear pump 10 in large displacement operational state.
  • the variable displacement type gear pump 10 includes a body 11 which accommodates drive gears 22, 25 and driven gears 23, 26 therein.
  • the body 11 has two spaces which are formed so as to extend from both axial end faces of the body 11.
  • One space is a first gear chamber 12 and the other space is a second gear chamber 13.
  • the second gear chamber 13 serves as a specific gear chamber.
  • a partition 14 is formed between the first gear chamber 12 and the second gear chamber 13.
  • a front housing 15 is joined to one end of the body 11.
  • a rear housing 16 is joined to the other end of the body 11.
  • the body 11, the front housing 15, the rear housing 16 constitute a housing assembly.
  • the body 11 and the front and the rear housings 15, 16 are joined by through bolts 30 with each other as shown in Fig. 2 .
  • the front side where the front housing 15 is located corresponds to the left side in the drawings (referring to Figs. 1 , 3 , and 4 ).
  • the rear side where the rear housing 16 is located corresponds to the right side in the drawings.
  • the front housing 15 closes the first gear chamber 12, and the rear housing 16 closes the second gear chamber 13.
  • a side plate 17 is interposed between the first gear chamber 12 and the end face of the front housing 15, and a side plate 18 is interposed between the second gear chamber 13 and the end face of the rear housing 16, Similarly, a side plate 19 is interposed between the first gear chamber 12 and the partition 14, and a side plate 20 is interposed between the second gear chamber 13 and the partition 14.
  • the drive gear 22 and the driven gear 23 at the front side are externally engaged with each other so as to form a first gear mechanism 21.
  • the first gear mechanism 21 is accommodated in the first gear chamber 12 as shown in Figs. 2 and 3 .
  • the drive gear 25 and the driven gear 26 at the rear side are externally engaged with each other so as to form a second gear mechanism 24.
  • the second gear mechanism 24 is accommodated in the second gear chamber 13 as shown in Fig. 3 .
  • the front drive gear 22 accommodated in the first gear chamber 12 is formed integrally with a drive shaft 27.
  • the drive gear 22 is coaxial with the drive shaft 27.
  • the rear drive gear 25 is fitted to the drive shaft 27 by way of spline coupling or serration coupling.
  • the drive gear 25 is coaxial with the drive shaft 27. That is, the drive gears 22, 25 are formed so as to have a common rotational axis.
  • the drive shaft 27 extends through the side plates 17, 18, 19, 20 and the partition 14 into the front housing 15 and the rear housing 16.
  • the drive shaft 27 is rotatably supported by the body 11, the front housing 15, and the rear housing 16 through a bearing 29.
  • One end of the drive shaft 27 extends out of the front housing 15 so as to be connected to an external drive source which is not shown, and receives driving force from the external drive source.
  • the front driven gear 23 is formed integrally with a driven shaft 28, and is coaxial with the driven shaft 28.
  • the rear driven gear 26 is fitted to the driven shaft 28 by way of spline coupling or serration coupling.
  • the driven gear 26 is coaxial with the driven shaft 28. Similar to the drive shaft 27, the driven shaft 28 extends into the front housing 15 and the rear housing 16.
  • the driven shaft 28 is supported by the body 11, the front housing 15 and the rear housing 16 through an another bearing 29.
  • the driven gears 23, 26 are formed so as to have a common rotational axis. Unlike the drive shaft 27, the end of the driven shaft 28 does not extend out of the front housing 15.
  • the first gear chamber 12 includes a suction-side space 31 and a discharge-side space 32 defined by the inner surface of the first gear chamber 12, the drive gear 22, and the driven gear 23.
  • the suction-side space 31 is formed at the suction side for introducing oil as a fluid.
  • the discharge-side space 32 is formed at the discharge side for discharging the oil.
  • a suction-side space 33 and a discharge-side space 34 are defined in the second gear chamber 13 as shown in Fig. 1 .
  • a front suction passage 36 is formed in the body 11 along the rotational axes of the drive shaft 27 and the driven shaft 28.
  • the oil is introduced into the first and the second gear chambers 12, 13 through the front suction passage 36.
  • a rear suction passage 37 is formed in the rear housing 16 and communicates with the front suction passage 36.
  • the rear suction passage 37 has an inlet 38 which is open at the axial end face of the rear housing 16.
  • the inlet 38 is in communication with the outside.
  • the front suction passage 36 and the rear suction passage 37 have circular cross-sectional surfaces, respectively.
  • the front and rear suction passages 36, 37 are linearly connected with each other.
  • the front suction passage 36 and the rear suction passage 37 constitute a suction passage 35.
  • the suction passage 35 is communicated with the suction-side spaces 31, 33.
  • the oil from the outside of the variable displacement type gear pump 10 flows into the first and the second gear chambers 12, 13 through the suction passage 35.
  • a front discharge passage 42 and a rear discharge passage 43 are formed in the body 11 for discharging the oil pressurized in the gear chambers 12, 13 to the outside.
  • the front discharge passage 42 extends from the discharge-side space 32 of the first gear chamber 12.
  • the rear discharge passage 43 extends from the discharge-side space 34 of the second gear chamber 13.
  • the front and rear discharge passages 42, 43 are connected with each other so as to flow into a single outlet passage 41 downstream thereof inside the body 11. Thereby the outlet passage 41 communicates with the discharge-side spaces 32, 34 through the front and rear discharge passages 42, 43. Further, the outlet passage 41 has an outlet 44 which is in communication with the outside.
  • the oil is discharged to the outside of the gear pump 10 through the outlet passage 41 and the outlet 44, and is supplied to a hydraulic circuit which is connected to a hydraulic device, which is not shown.
  • a check valve 45 is provided in the rear discharge passage 43 in the body 11 and is located between the discharge-side space 34 of the specific gear chamber 13 and the outlet passage 41. The check valve 45 serves to prevent the oil discharged from the gear chamber 12, which is other than the specific gear chamber 13 (second gear chamber 13), from flowing into the discharge-side space 34 of the specific gear chamber 13 in a small displacement state.
  • the check valve 45 includes a ball-shaped valve body 46, a coil spring 47, and a support member 48.
  • the valve body 46 opens and closes the rear discharge passage 43.
  • the coil spring 47 is an urging device for urging the valve body 46.
  • the support member 48 supports the coil spring 47.
  • the coil spring 47 applies urging force to the valve body 46 in the direction to close the rear discharge passage 43.
  • the valve body 46 is moved in the direction to open the rear discharge passage 43 against the urging force of the coil spring 47 when the pressure in the rear discharge passage 43 is equal to or greater than a predetermined value.
  • the valve body 46 closes the rear discharge passage 43 by the urging force of the coil spring 47 when the pressure in the rear discharge passage 43 is below the predetermined value.
  • the urging force of the coil spring 47 may be set small, since the valve body 46 is urged to a seat surface in the support member 48 by the pressure difference.
  • the form of the valve body 46 is not limited to the ball-shape, and may be a conical shape.
  • the rear housing 16 includes a return passage 50.
  • the return passage 50 communicates with the rear discharge passage 43, and also communicates with the rear suction passage 37. That is, the return passage 50 communicates with the suction passage 35 and the discharge-side space 34 of the second gear chamber 13 so as to return the oil discharged to the discharge-side space 34 to the suction passage 35.
  • An opening and closing valve 51 is provided in the return passage 50 to open and close the return passage 50.
  • the valve 51 has a piston mechanism in which a cylindrical piston 53 is slidably accommodated in a hollow cylinder 52 with a bottom.
  • the valve 51 opens and closes the return passage 50 by the sliding movement of the piston 53 in the cylinder 52.
  • the sliding movement of the piston 53 is performed by the pressure difference applied to the both end faces of the piston 53. That is, the sliding movement of the piston 53 is performed by the pressure difference between the pressure in the space at the side of the return passage 50 and the pressure in the space in the cylinder 52 at the opposite side of the piston 53.
  • the pressure difference applied on the both end faces of the piston 53 is controlled by the actuation of an electromagnetic valve 55 in the rear housing 16.
  • the electromagnetic valve 55 includes a spool 57, a coil 58, and a coil spring 59.
  • the spool 57 slides in a spool hole 56 formed in the rear housing 16.
  • the coil 58 moves the spool 57 frontward.
  • the coil spring 59 is an urging device for urging the spool 57.
  • the spool hole 56 is in communication with the downstream side of the return passage 50.
  • the spool 57 includes a suction-pressure communication passage 60 for communicating the return passage 50 to the cylinder 52.
  • the spool 57 is moved frontward.
  • the spool 57 is moved rearward by the coil spring 59.
  • a discharge-pressure communication passage 61 is formed in the body 11 and the rear housing 16 for supplying the oil under discharge pressure from the rear discharge passage 43 to the spool hole 56.
  • the discharge-pressure communication passage 61 includes passages 62, 63 and a groove 64.
  • the groove 64 is formed at the outer periphery of the spool 57.
  • variable displacement type gear pump 10 of the first preferred embodiment according to the present invention.
  • the first gear mechanism 21 and the first gear chamber 12 at the front side constitute a front gear pump portion P1.
  • the second gear mechanism 24 and the second gear chamber 13 at the rear side constitute a rear gear pump portion P2.
  • the front gear pump portion P1 and the rear gear pump portion P2 respectively have 50 percent of the entire discharge displacement of the variable displacement type gear pump 10.
  • the oil introduced in the suction-side space 31 is confined in a space defined by teeth of the drive gear 22 and the inner surface of the first gear chamber 12, and also in a space defined by teeth of the driven gear 23 and the inner surface of the first gear chamber 12.
  • the oil confined in the spaces is transferred along the inner surface of the first gear chamber 12 in the rotational direction of the drive gear 22 and the rotational direction of the driven gear 23, respectively.
  • the oil confined in the spaces is discharged to the discharge-side space 32.
  • the oil in the discharge-side space 32 is discharged to the outside of the gear pump 10 through the front discharge passage 42, the outlet passage 41, and the outlet 44, and delivered to a hydraulic device not shown to operate the hydraulic device.
  • the discharge pressure is increased in accordance with the load of the hydraulic device.
  • the front gear pump portion P1 when the driving force is applied to the drive shaft 27 from the outside, the drive gear 22 and the driven gear 23 in the first gear chamber 12 are driven, and the oil is discharged to the discharge-side space 32.
  • the discharged oil is supplied to the front discharge passage 42.
  • the rear gear pump portion P2 when the driving force is applied to the drive shaft 27 from the outside, the drive gear 25 and the driven gear 26 in the second gear chamber 13 are driven, and the oil is discharged to the discharge-side space 34.
  • the spool 57 When the coil 58 of the electromagnetic valve 55 is not excited, the spool 57 is located in the rear position, by receiving the urging force of the coil spring 59. When the spool 57 is located in the rear position, the discharge-pressure communication passage 61 is communicated with the cylinder 52 of the valve 51. The communication between the suction-pressure communication passage 60 and the cylinder 52 is shut off. Therefore, the oil is introduced from the rear discharge passage 43 through the discharge-pressure communication passage 61, and the cylinder 52 is filled with the oil under the discharge pressure. In the state where the piston 53 does not close the return passage 50 yet, the pressure in the return passage 50 communicating with the suction passage 35 is lower than the pressure in the cylinder 52, and the piston 53 is moved in the direction to close the return passage 50.
  • the discharge displacement of the variable displacement type gear pump 10 is 100 percent, and the gear pump 10 is in the large displacement operational state.
  • the large displacement operational state of 100 percent may be set to correspond to the load lifting-up state.
  • the piston 53 has a larger diameter at the side adjacent to the cylinder 52 (rear side), and is reliably urged frontward to close the return passage 50, even when the pressures at the front and rear sides of the piston 53 are equal with each other.
  • the spool 57 receives the frontward force overcoming the urging force of the coil spring 59, and is moved frontward.
  • the communication between the discharge-pressure communication passage 61 and the cylinder 52 is shut off.
  • the spool hole 56, the suction-pressure communication passage 60, and the cylinder 52 are communicated with each other.
  • the pressure in the cylinder 52 of the valve 51 is decreased from the discharge pressure to the suction pressure.
  • the piston 53 is moved into the cylinder 52 by receiving the pressure difference when the pressure in the cylinder 52 becomes the suction pressure. By the retreat of the piston 53 into the cylinder 52, the return passage 50 becomes to the opened state.
  • the valve body 46 closes the rear discharge passage 43 by the urging force of the coil spring 47 of the check valve 45.
  • the check valve 45 closes the rear discharge passage 43 and the valve 51 opens the return passage 50, only the oil discharged from the front gear pump portion P1 is delivered to the outside through the outlet passage 41.
  • the oil discharged from the rear gear pump portion P2 is supplied to the return passage 50. Then the oil joins the upstream side of the suction passage 35 at a confluence portion, that is, between the inlet 38 of the suction passage 35 and the suction-side space 33.
  • the confluence portion is located upstream side of the suction-side spaces 31, 33 which communicate with the suction passage 35 in the gear pump 10. Therefore, in this state, the discharge displacement of the variable displacement type gear pump 10 gets to 50 percent, and is in the small displacement operational state.
  • the state where the electromagnetic valve 55 is activated is set as the 50-percent discharge displacement.
  • the location of the groove 64 and the suction-pressure communication passage 60 in the spool 57 may be modified so that a state activating the electromagnetic valve 55 is set as 100-percent discharge displacement, while a state deactivating the electromagnetic valve 55 is set as 50-percent discharge displacement.
  • the oil from the return passage 50 joins the upstream side of the suction passage 35 at the confluence portion.
  • the oil in the suction passage 35 is supplied to the front gear pump portion P1 and the rear gear pump portion P2.
  • the oil in the suction passage 35 is in the state where newly introduced oil from the inlet 38 is mixed with the returned oil from the return passage 50. That is, even if the small displacement operation is continued, the oil flowing through the return passage 50 does not continuously circulate in the rear gear pump portion P2 and the return passage 50.
  • the suction passage 35 is formed in the body 11 along the rotational axes of the drive shaft 27 and the driven shaft 28, and it is not required to form a suction passage 35 outside of the body 11.
  • the first preferred embodiment has the following advantageous effects.
  • the second preferred embodiment will be described according to Fig. 5 .
  • the gear pump of the second preferred embodiment differs from that of the first embodiment in that the structure of the return passage is modified, and the rest of the structure of the gear pump of the second embodiment is substantially the same as the first embodiment. Therefore, like or same parts or elements will be referred to by the same reference numerals as those in the first embodiment, and the description thereof will be omitted.
  • a variable displacement type gear pump 71 has a return passage 72.
  • the return passage 72 connects the rear discharge passage 43 and the rear suction passage 37.
  • the downstream side of the return passage 72 is formed substantially linearly in the radial direction in the roar housing 16.
  • the return passage 72 communicates with the upstream side of the suction passage 35 at a confluence portion.
  • a guide portion 73 is formed at the confluence portion, or at the vicinity of the end of the return passage 72 in the rear housing 16 so as to incline the return passage 72 frontward. The inclination at the vicinity of the end of the return passage 72 by the guide portion 73 is in the direction to increase the flow speed of the newly introduced oil in the suction passage 35 by introducing the oil from the return passage 72 into the suction passage 35.
  • the oil discharged from the rear gear pump portion P2 at the small displacement operation flows through the return passage 72.
  • the oil flowing through the return passage 72 joins the newly introduced oil flowing through the suction passage 35.
  • the oil in the return passage 72 flows in the direction perpendicular to the oil flow in the suction passage 35, and then is guided by the guide portion 73 so as to flow frontward.
  • the oil guided by the guide portion 73 joins the oil in the suction passage 35 so as to flow in the direction to increase the speed of the oil flow.
  • the guide portion 73 guides the oil of the return passage 72 into the suction passage 35 so as to increase the speed of the oil flow in the suction passage 35 at the small displacement operation. Thereby the oil flowing in the return passage 72 can be effectively mixed with the newly introduced oil into the suction passage 35.
  • Fig. 6 is a partially enlarged cross-sectional view of a variable displacement type gear pump 81 according to the third preferred embodiment, and taken along a return passage 82 in the rear housing 16.
  • the gear pump of the third preferred embodiment differs from that of the first embodiment in that the structure of the return passage is modified, and the rest of the structure of the gear pump of the third embodiment is substantially the same as the first embodiment. Therefore, like or same parts or elements will be referred to by the same reference numerals as those in the first embodiment, and the description thereof will be omitted.
  • the suction passage 35 in the variable displacement type gear pump 81 has a circular cross-sectional surface.
  • the rear suction passage 37 in the rear housing 16 has a circular cross-sectional surface.
  • the rear discharge passage 43 and the suction passage 35 are connected by the return passage 82.
  • the return passage 82 communicates with the suction passage 35 at a confluence portion located the upstream side of the suction passage 35.
  • the confluence portion of the return passage 82 is formed by connecting the return passage 82 in the tangent direction with respect to the circular cross-sectional surface of the rear suction passage 37, as shown in Fig. 6 .
  • the oil flowing through the return passage 82 enhances the swirling flow of the oil flowing through the suction passage 35.
  • the return passage 82 is connected to the suction passage 35 in the tangent direction with respect to the circular cross-sectional surface of the suction passage 35.
  • the oil flowing through the return passage 82 at the small displacement operation is introduced into the suction passage 35 along the inner circumferential surface of the suction passage 35.
  • the oil joining together while being guided along the inner circumferential surface of the suction passage 35 enhances the swirling flow in the suction passage 35. With the swirling flow in the suction passage 35, the newly introduced oil in the suction passage 35 is effectively mixed with the oil from the return passage 82.
  • variable displacement type gear pump of a fourth preferred embodiment differs from that of the first embodiment in that the structure of the return passage is modified, and the rest of the structure of the gear pump of the fourth embodiment is substantially the same as the first embodiment. Therefore, like or same parts or elements will be referred to by the same reference numerals as those in the first embodiment, and the description thereof will be omitted.
  • Fig. 7 shows a variable displacement type gear pump 91 in small displacement operational state.
  • the gear pump 91 has a return passage 92 which connects the rear discharge passage 43 and the rear suction passage 37.
  • the return passage 92 is connected to the upstream side of the suction passage 35 so as to form a confluence portion.
  • the confluence portion of the return passage 92 with the suction passage 35 has a parallel guide portion 94 at the end of the return passage 92 adjacent the suction passage 35.
  • the parallel guide portion 94 is formed so as to guide the oil flow from the return passage 92 frontward and parallel to the suction passage 35.
  • the oil from the return passage 92 joins parallely the oil flowing through the suction passage 35.
  • the oil from the return passage 92 joins the upstream side of the suction passage 35.
  • the oil flow from the return passage 92 is parallel to the oil flow in the suction passage 35. Since the oil flow from the return passage 92 does not have a velocity component in the traverse direction with respect to the suction passage 35, the dynamic pressure of the oil from the return passage 92 is effectively introduced into the suction-side space 31 for increasing the pressure therein.
  • the pressure difference between the discharge-side space 32 and the suction-side space 31 at the front side is going to be decreased, compared to a case without the guide portion 94.
  • the decreased pressure difference between the spaces 31, 32 affects the load applied on the front gear pump portion P1 being reduced.
  • the reduction of oil leakage is effective in increasing the volume efficiency. Further, due to the pressure difference between the spaces 31, 32, the load applied from the drive shaft 27 and the driven shaft 28 to the bearings 29 is reduced. Thereby the sliding friction between the shafts 27, 28 and the bearings 29 is reduced and the mechanical efficiency is improved.
  • the outflow of the oil from the return passage 92 joins the oil in the suction passage 35 flowing in the same direction, and the pressure of the oil in the suction passage 35 downstream side of the confluence portion is increased. Due to the pressure increase of the oil in the suction passage 35, the cavitation in the oil is in advance prevented.
  • the fourth preferred embodiment has the following advantageous effects.
  • the maximum displacement of the variable displacement type gear pump when the maximum displacement of the variable displacement type gear pump is set as 100 percent, and the displacement of each of the front and rear gear pump portions is set as 50 percent.
  • the performance of the gear pump portions is not limited to 50 percent.
  • the performance of the each gear pump portion is set appropriately, for example, as 70 percent and 30 percent, depending on the condition.
  • gear pump portions that Is, the front gear portion and the rear gear portion are provided, however, the number of gear pump portion may be more than two.
  • the oil discharged from at least one gear pump portion may be returned through the return passage at the small displacement operation.
  • the suction passage has the circular cross-sectional surface over the entire longitudinal direction.
  • the suction passage may not have a circular cross-sectional surface in the first, second, and fourth embodiments.
  • the cross-sectional surface of the suction passage may be, for example, polygonal, elliptical, or oblong shape.
  • the cross-sectional surface of the suction passage may be formed only at the vicinity of the confluence portion with the return passage. Specifically, if the downstream side of the confluence portion has a circular cross-sectional surface, it is appropriate for enhancing the swirling flow of oil in the suction passage.
  • the discharge passages are provided so as to connect the discharge-side spaces of the gear chambers and the outlet passage.
  • the discharge-side space of each gear chamber may be connected directly to the outlet passage without a discharge passage. In this case, a check valve is required to shut off the outlet passage connecting the gear chambers.
  • the return passage is formed so as to pass through the rear side of the rear ends of the drive shaft and the driven shaft.
  • the location of the return passage is not limited to the above position.
  • the return passage may pass around at least one of the outer peripheries of the drive shaft and the driven shaft.
  • the return passage may be preferably formed between the rear gear chamber and the rear ends of the drive shaft and the driven shaft, in order to form the confluence portion of the return passage with the suction passage at the upstream side of the suction passage.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Rotary Pumps (AREA)
  • Details And Applications Of Rotary Liquid Pumps (AREA)
EP08014138A 2007-08-09 2008-08-07 Zahnradpumpe mit variabler Verdrängung Withdrawn EP2022985A2 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2007207331 2007-08-09
JP2008030926A JP2009062970A (ja) 2007-08-09 2008-02-12 可変容量型ギヤポンプ

Publications (1)

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EP2022985A2 true EP2022985A2 (de) 2009-02-11

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EP08014138A Withdrawn EP2022985A2 (de) 2007-08-09 2008-08-07 Zahnradpumpe mit variabler Verdrängung

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US (1) US20090041593A1 (de)
EP (1) EP2022985A2 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014168830A3 (en) * 2013-04-11 2014-12-24 Caterpillar Inc. Gear pump having grooved mounting adapter
CN104806518A (zh) * 2015-03-31 2015-07-29 徐工集团工程机械股份有限公司道路机械分公司 一种使齿轮泵实现变排量的电控合流泵

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5104656B2 (ja) * 2008-08-26 2012-12-19 株式会社豊田自動織機 可変容量型回転式ポンプ
US20110129359A1 (en) * 2009-11-30 2011-06-02 Caterpillar Inc. Variable output pump
US9028222B2 (en) 2011-08-26 2015-05-12 Hamilton Sundstrand Corporation Variable output pump
US20150337731A1 (en) * 2013-01-18 2015-11-26 United Technologies Corporation Oil pump transfer plate
JP6381871B2 (ja) * 2013-06-04 2018-08-29 株式会社ミクニ 流体ポンプ
CN105518302B (zh) * 2013-09-30 2017-02-15 爱信艾达株式会社 车辆用油压供给装置
DE102014216038A1 (de) * 2014-08-13 2016-02-18 Robert Bosch Gmbh Zahnradmaschine mit schaltbarem internem Umlauf
US10815991B2 (en) 2016-09-02 2020-10-27 Stackpole International Engineered Products, Ltd. Dual input pump and system
CA3124623A1 (en) 2018-12-31 2020-07-09 Stackpole International Engineered Products, Ltd. Pump assembly having two pumps provided in a single housing
CN111059048B (zh) * 2020-01-17 2023-11-10 宿迁学院 一种利用困油力抵消部分径向力的浮动侧板

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002070757A (ja) 2000-08-31 2002-03-08 Tokico Ltd 可変容量ギヤポンプ

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2108771A (en) * 1935-01-30 1938-02-15 Wicaco Machine Corp Fluid pump
US2640422A (en) * 1946-12-03 1953-06-02 Texas Co Fuel pump for internal-combustion engines
US5110269A (en) * 1990-10-24 1992-05-05 General Electric Company Gas turbine fuel pumping apparatus
US6544008B1 (en) * 1997-07-18 2003-04-08 John K. Apostolides Internal vent for reducing seal pressure in prelubrication pump assembly

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002070757A (ja) 2000-08-31 2002-03-08 Tokico Ltd 可変容量ギヤポンプ

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014168830A3 (en) * 2013-04-11 2014-12-24 Caterpillar Inc. Gear pump having grooved mounting adapter
US9046101B2 (en) 2013-04-11 2015-06-02 Caterpillar Inc. Gear pump having grooved mounting adapter
CN105247218A (zh) * 2013-04-11 2016-01-13 卡特彼勒公司 具有开槽的装配转接器的齿轮泵
CN104806518A (zh) * 2015-03-31 2015-07-29 徐工集团工程机械股份有限公司道路机械分公司 一种使齿轮泵实现变排量的电控合流泵

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