JP2010053692A - Variable displacement rotary pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent generation of impact and noise when switching to high capacity operation from low capacity operation, in a variable displacement rotary pump. <P>SOLUTION: Switching to 100% operation from 50% operation of a variable displacement gear pump is performed without carrying an electric current to an electromagnet. A spool valve 55 moves backward, and an annular groove 57 communicates with a through-hole 61 and a groove 62. Delivery oil flows in an inside space 50 from a delivery pressure communicating passage 63, and moves a spool valve 44 forward. When the spool valve 44 moves to a finishing stage of closing operation of an opening-closing valve 42, an annular groove 51 of the spool valve 44 slips out of a communicating state with the through-hole 61. Oil is restricted by a clearance 67, and is supplied to the annular groove 51. Since a supplied oil quantity is reduced, a moving speed of the spool valve 44 is reduced, and a valve part 46 abuts on a valve seat 48 at a slow speed, and completes closing operation of a bypass passage 32. Thus, generation of the impact and the noise when closing the bypass passage 32 can be prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a variable displacement rotary pump including a plurality of pumps and capable of changing the amount of fluid supplied to the outside.

  For example, Patent Document 1 discloses a variable displacement gear pump as a variable displacement rotary pump. The variable displacement gear pump disclosed in Patent Document 1 houses a drive gear and two driven gears that mesh with the drive gear in a casing, and operates as a first pump and a second pump of two systems (double gear pump). ).

  Specifically, a check valve is provided between the common discharge port connected to the discharge passage of the first gear pump constituting the first pump and the discharge passage of the second gear pump constituting the second pump. Yes. A common outlet connects to the hydraulic system and supplies oil. An unload passage (oil return passage) connected to the suction port of the second gear pump is piped between the discharge port of the second gear pump and the check valve, and an electromagnetic on-off valve is connected to the unload passage. Is provided.

  When the electromagnetic on-off valve is closed, the first pump and the second pump are operated in parallel to increase the discharge capacity to the outside, and in this state, the high capacity operation is performed. When the electromagnetic on-off valve is opened, the second pump is unloaded, so that the discharge capacity to the outside is reduced, and in this state, low capacity operation is performed.

JP 2002-70757 A (page 3-4, FIG. 1)

  In the variable displacement gear pump disclosed in Patent Document 1, the electromagnetic on-off valve of the second gear pump is operated to open or close the unload passage in order to reduce or increase the amount of oil supplied to the external hydraulic system. There must be. During low capacity operation, the unload passage is open and the check valve is closed, so that all the oil discharged from the second gear pump flows from the unload passage to the suction port.

  Switching from low-capacity operation to high-capacity operation is performed by opening the check valve and closing the electromagnetic on-off valve. However, since the electromagnetic on-off valve immediately closes the unload passage, a large amount of oil flowing through the unload passage is instantaneously stopped. For this reason, an impact such as oil hammer occurs due to a sudden increase in the discharge capacity to the outside and a sudden increase in the pressure in the discharge port. The impact may damage the external hydraulic system and the pump itself, and causes problems such as noise generated by the impact.

  The present invention prevents the occurrence of impact and noise when switching from low capacity operation to high capacity operation in a variable displacement rotary pump.

  The present invention according to claim 1 is to return a main pump, a sub pump, a check valve disposed in a discharge passage for supplying the discharge fluid of the sub pump to the outside, and a discharge fluid of the sub pump to the suction side. In a variable capacity rotary pump that includes an opening / closing valve provided in a bypass passage and changes the amount of fluid supplied to the outside by different opening / closing operation of the check valve and the opening / closing valve, in the direction of closing the opening / closing valve An operating fluid supply passage is connected to the on-off valve, and a throttling passage is provided in the fluid supply passage for at least an end stage of the closing operation of the on-off valve.

  According to the first aspect of the present invention, since the on-off valve is decelerated at the end of the closing operation, and the bypass passage is closed slowly, a sudden increase in the discharge flow rate when changing the fluid supply amount to the outside, It is possible to prevent the sudden increase of the discharge pressure and to prevent the generation of impact and noise.

  According to a second aspect of the present invention, the on-off valve is slidably disposed in the valve hole, and a position contacting the valve seat formed in a part of the bypass passage and a position spaced from the valve seat The throttle passage is formed as a gap for sliding the spool valve formed between the outer peripheral surface of the spool valve and the inner wall surface of the valve hole. Therefore, the sliding clearance of the spool valve can be used, and the throttle passage can be easily configured.

  The invention according to claim 3 is characterized in that the throttle passage is configured such that the throttle amount is gradually increased until the on-off valve closes the bypass passage. , And the discharge flow rate can be increased smoothly. The invention of claim 3 is suitable when a spool valve is used as the on-off valve, when the gap for sliding the spool valve tends to be excessively throttled.

  The invention of claim 4 can obtain the same effect as that of claim 3 by forming at least a part of the surface of the throttle passage in a tapered shape.

  According to the fifth aspect of the present invention, the same effect as that of the third aspect can be obtained by forming at least a part of the surface of the throttle passage as a stepped surface having a stepped cross section.

  The present invention according to claim 6 is characterized in that the on-off valve is actuated by a pilot valve, so that the on-off valve actuating means can be configured simply.

  According to the seventh aspect of the present invention, since the rotary pump is constituted by a gear pump, it is possible to suppress impact and noise that are likely to occur when the on-off valve is closed in the variable displacement gear pump.

  The present invention makes it possible to slow down the moving speed of the on-off valve at least at the end stage of the closing operation of the on-off valve, and to prevent the occurrence of impact and noise at the time of closing.

(First embodiment)
A first embodiment implemented in a variable displacement gear pump that uses oil as a fluid will be described with reference to FIGS.
As shown in FIG. 1, the housing 1 of the variable displacement gear pump has a structure in which a front housing 3 and a rear housing 4 are joined to both sides of a central body 2 and integrated by through bolts 5 shown in FIG. . In the present specification, the front housing 3 side is assumed to be the front, and the rear housing 4 side is assumed to be the rear. Further, the upper side of FIG. 1 will be referred to as the upper side, the lower side will be referred to as the lower side, the left side of FIG.

  The body 2, the front housing 3 and the rear housing 4 rotatably support a drive shaft 6 passing through the body 2 and a driven shaft 7 (see FIG. 2) arranged in parallel with the drive shaft 6 by a bearing 8. The drive shaft 6 includes a first drive gear 9 that is integrally formed with the drive shaft 6 and a second drive gear 10 that is spline fitted onto the drive shaft 6. Similarly, the driven shaft 7 includes a first driven gear 11 that is integrally molded and a second driven gear (not shown) that is spline-fitted. The front end portion of the drive shaft 6 protrudes outward from the front housing 3 and is connected to an external power source (not shown).

  A first gear chamber 13 is formed in the body 2 so as to be sealed between the rear side surface of the front housing 3 with the partition portion 12 interposed therebetween, and a second gear chamber 13 is sealed between the front side surface of the rear housing 4. A gear chamber 14 is formed. As shown in FIG. 2, the first gear chamber 13 is formed in a cross-sectional glasses shape that connects two circular spaces, and the first drive gear 9 of the drive shaft 6 and the first driven gear 11 of the driven shaft 7 are contained therein. Store in a meshed state. The second gear chamber 14 is formed in a space having the same shape as that of the first gear chamber 13, and a state in which the second drive gear 10 of the drive shaft 6 and the second driven gear (not shown) of the driven shaft 7 are engaged with each other. To house.

  Between the front side surface of the first drive gear 9 and the first driven gear 11 and the rear side surface of the front housing 3, and between the rear side surface of the first drive gear 9 and the first driven gear 11 and the front side surface of the partition portion 12. Each includes a side plate 15 and a gasket 16 having a cross-sectional glasses shape similar to that of the first gear chamber 13. Similarly, between the second drive gear 10 and the second driven gear (not shown) and the rear side surface of the partition portion 12, the second drive gear 10 and the second driven gear (not shown) and the front of the rear housing 4. A side plate 17 and a gasket 18 are interposed between the side surfaces.

  Each of the side plates 15 and 17 is formed with arc-shaped grooves 19 on the side surfaces that are in contact with the first drive gear 9 and the second drive gear 10, and the first driven gear 11 and the second driven gear (not shown). An arcuate groove 20 is formed on each of the contact side surfaces. As shown in FIG. 2, the grooves 19 of the side plates 15 and 17 are approximately 3 from the oil discharge side (upper side in FIG. 2), which will be described later, toward the counter-rotating direction of the first drive gear 9 and the second drive gear 10. In a region of about one-half, the first drive gear 9 and the second drive gear 10 are arranged so as to correspond to the teeth.

  Similarly, the grooves 20 of the side plates 15 and 17 that are in contact with the first driven gear 11 and the second driven gear (not shown) are arranged on the oil discharge side (upper side in FIG. 2) from the first driven gear 11 and the second driven gear. In a region of about one third of the gear (not shown) facing in the counter-rotating direction, the gear is arranged to correspond to the teeth of the first driven gear 11 and the second driven gear (not shown). .

  The grooves 19 and 20 are formed in the inner peripheral walls of the first gear chamber 13 and the second gear chamber 14 by the first drive gear 9, the first driven gear 11, the second drive gear 10, and the second driven gear (not shown). It has the function of receiving the oil conveyed along and discharging it to the discharge side. The gasket 18 has a function of preventing backlash in the thrust direction of the first drive gear 9, the first driven gear 11, the second drive gear 10, and the second driven gear (not shown).

  Under the first gear chamber 13 and the second gear chamber 14, suction side spaces 22 and 23 are formed, respectively, and communicate with a common suction passage 21 disposed in the lower part of the body 2 in parallel with the drive shaft 6. is doing. The suction passage 21 communicates with an external oil tank (not shown) through a common suction passage 24 and a suction port 25 on the rear side disposed in the lower portion of the rear housing 4. Discharge side spaces 26 and 27 are formed above the first gear chamber 13 and the second gear chamber 14, respectively.

  In the upper part of the body 2, a common discharge passage 28 is disposed in parallel with the drive shaft 6, and discharge-side space portions 26 and 27 communicate with the discharge passage 28, respectively. Therefore, the oil discharged from the first gear chamber 13 and the second gear chamber 14 to the discharge side spaces 26 and 27 joins the discharge passage 28 and is connected to an external hydraulic device or the like via the discharge port 29. (Not shown). The first gear chamber 13, the suction side space 22 and the discharge side space 26 constitute a main pump 30, and the second gear chamber 14, the suction side space 23 and the discharge side space 27 are sub-pumps 31. Configure.

  The discharge side space 27 of the sub pump 31 communicates with the bypass passage 32 separately from the discharge passage 28. The bypass passage 32 is disposed in the rear housing 4 and has a bent shape including a passage parallel to the drive shaft 6 and a passage perpendicular to the drive shaft 6, and communicates with the suction passage 24 on the rear side. The bypass passage 32 may be configured to communicate with the suction passage 21. A check valve 33 is disposed at a position where the discharge side space 27 of the second gear chamber 14 communicates with the discharge passage 28. The closing operation of the check valve 33 prevents the oil discharged from the sub pump 31 from joining the oil discharged from the main pump 30 in the discharge passage 28.

  The check valve 33 includes a bottomed cylindrical main body 34 having an external thread on the outer periphery, a bottomed cylindrical valve body 35 slidably fitted to the main body 34 from the opening side, and a main body 34 in the inner space of the valve body 35. It is comprised from the coiled compression spring 36 interposed between these. The strength of the compression spring 36 can be set freely, but when a strong compression spring is used, the closing speed of the valve body 35 can be increased. A through hole 37 and a through hole 38 are formed in the bottomed peripheral surface of the valve body 35 and the main body 34, respectively, and a communication hole 39 that opens to the discharge port 29 is formed in the upper part of the body 2. ing.

  The through-hole 37, the through-hole 38, and the communication hole 39 communicate with the valve body 35 when it rises most (when the check valve 33 is opened), and a part of the discharged oil flowing into the discharge port 29 flows into the valve body 35. To do. Therefore, the valve body 35 receives a downward biasing force by the compression spring 36 and the discharge oil. Above the discharge side space 27 of the second gear chamber 14, a valve seat 40 is disposed in a part of the body 2 that forms the discharge passage 28. When the valve body 35 is lowered and comes into contact with the valve seat 40, the discharge passage 28 is disconnected from the communication state between the main pump 30 side and the sub pump 31 side. Even though the valve body 35 is lowered, the through hole 37 communicates with the discharge passage 28, so that the discharge oil of the main pump 30 flows from the through hole 37 and continuously receives the downward urging force by the discharge oil. ing.

  An open / close valve 42 that opens and closes by an electromagnetic pilot valve 41 is disposed at a bent portion of the bypass passage 32. The on-off valve 42 basically includes a valve hole 43 formed in the rear housing 4 in the front-rear direction and a bottomed cylindrical spool valve 44 that is slidably fitted in contact with the inner wall surface of the valve hole 43. Become. The valve hole 43 is formed as a passage having a larger diameter than the bypass passage 32 on the extension of the bypass passage 32 parallel to the drive shaft 6. The opening of the valve hole 43 penetrating to the rear of the rear housing 4 is sealed with a closing bolt 45.

  The spool valve 44 has a conical surface-like valve portion 46 on the outer periphery on the front end side, and the front end of the valve portion 46 has a cylindrical portion 47 formed with a smaller diameter than the bypass passage 32 parallel to the drive shaft 6. When the spool valve 44 moves forward to close the bypass passage 32 and the valve portion 46 comes into contact with a valve seat 48 formed in a part of the bypass passage 32, the cylindrical portion 47 is parallel to the drive shaft 6. Enter the bypass passage 32. A fluid passage between the outer peripheral surface of the cylindrical portion 47 and the inner wall of the bypass passage 32 parallel to the drive shaft 6 is formed as a bypass passage restricting portion 49 including a gap parallel to the axial center line of the spool valve 44.

  In the bypass passage throttle section 49, the size of the gap, which is the throttle amount, and the length of the gap in the front-rear direction, which is the throttle time, are set in accordance with the closing speed of the valve body 35 of the check valve 33. This configuration prevents the amount of oil flowing from the bypass passage 32 to the rear suction passage 24 from abruptly increasing. The internal space 50 of the spool valve 44 opens to the valve hole 43. An annular groove 51 formed on the outer peripheral surface of the spool valve 44 has a certain length in the axial direction of the spool valve 44 and communicates with the internal space 50 through an appropriate number of through holes 52.

  The electromagnetic pilot valve 41 is configured as follows. A valve hole 53 penetrating rearward of the rear housing 4 is formed in the rear housing 4 at a position below the valve hole 43 of the on-off valve 42. The front end of the valve hole 53 communicates with a through hole 54 having a smaller diameter than the valve hole 53. The through hole 54 opens to the bypass passage 32 at a position closer to the suction passage 24 on the rear side than the spool valve 44. A cylindrical spool valve 55 is fitted in the valve hole 53 so as to be slidable in the front-rear direction.

  The spool valve 55 has annular grooves 56 and 57 at two locations on the outer peripheral surface on the front end side, and has a suction pressure communication passage 58 at a substantially central portion. The suction pressure communication path 58 has a rear end bent in the radial direction of the spool valve 55 and connected to the annular groove 56, and a front end opened to the valve hole 53. The spool valve 55 is urged rearward by a coiled compression spring 59 interposed between the front end surface and the front inner wall of the valve hole 53, and is projected from the valve hole 53 to the rear end portion protruding rearward of the rear housing 4. Also has a large-diameter flange 60. Therefore, when the spool valve 55 is moved forward against the compression spring 59, the most advanced position is defined by the flange 60.

  A case 66 having an electromagnet 64 and a plunger 65 is fixed to the rear end surface of the rear housing 4 by appropriate means. The flange 60 of the spool valve 55 is inserted into the sliding passage of the plunger 65 and is in contact with the front end surface of the plunger 65. Accordingly, the spool valve 55 is moved forward by the plunger 65 when the electromagnet 64 is excited, and is moved rearward by the biasing force of the compression spring 59 when the electromagnet 64 is demagnetized.

  The valve hole 53 is connected to the valve hole 43 by a through hole 61 formed in the rear housing 4, and is connected to a groove 62 formed in the rear housing 4. The groove 62 is connected to a discharge pressure communication passage 63 opened in the discharge passage 28. The relationship between the through hole 61, the groove 62, and the annular grooves 56 and 57 is configured as follows. That is, when the spool valve 55 is moved rearward by the urging force of the compression spring 59, the annular groove 57 is in communication with the through hole 61 and the groove 62, and the annular groove 56 is in communication with the through hole 61 and the groove 62. It is shut off (see FIG. 1, FIG. 3, FIG. 5 to FIG. 7). When the spool valve 55 moves forward by the excitation of the electromagnet 64, the annular groove 56 communicates with the through hole 61, and the annular groove 57 is blocked from communicating with the through hole 61 and the groove 62 (see FIG. 4).

  On the other hand, when the spool valve 44 is moved forward and the valve portion 46 is in contact with the valve seat 48, the annular groove 51 and the through hole 61 do not directly communicate with each other, and are shifted by a certain distance as shown in FIG. Is set to The communication between the annular groove 51 and the through hole 61 in this state is formed between the outer peripheral surface of the spool valve 44 and the inner wall surface of the valve hole 43 so that the spool valve 44 can smoothly slide in the valve hole 43. The gap 67 is made. That is, the sliding gap 67 of the spool valve 44 is configured and used as a throttle passage for discharged oil supplied from the through hole 61 to the annular groove 51.

  The period during which the gap 67 functions as a throttle passage is the end stage of the closing operation of the on-off valve 42. As the end stage of the closing operation of the on-off valve 42, the timing when the valve portion 46 contacts the valve seat 48 from the timing before the valve portion 46 of the spool valve 44 contacts the valve seat 48 (the state immediately after FIG. 6). (State of FIG. 3) is set. Accordingly, when the annular groove 51 starts to be displaced from the through hole 61 as the spool valve 44 moves forward, the discharge oil supplied from the discharge pressure communication passage 63 is throttled by the gap 67, and only a small flow rate of the discharge fluid is annular. It is supplied to the groove 51. For this reason, the moving speed of the spool valve 44 is reduced, and the valve portion 46 contacts the valve seat 48 at a slow speed. The discharge pressure communication passage 63, the groove 62, the annular groove 57, and the through hole 61 constitute the fluid supply passage described in the present invention. Further, although the gap 67 shown in the drawing is shown relatively wide for convenience of explanation, it is actually designed in a narrow space necessary for sliding the spool valve 44.

  The operation of the variable displacement gear pump in the first embodiment configured as described above will be described. The discharge capacities of the main pump 30 and the sub pump 31 are the same. When only the oil discharged from the main pump 30 is supplied from the discharge port 29, it is at the time of low capacity 50% operation, and all the oil discharged from the main pump 30 and the sub pump 31 is supplied from the discharge port 29 Is during high capacity 100% operation. Therefore, the variable displacement gear pump in the first embodiment constitutes a gear pump that can change the discharge capacity in two stages of 50% and 100% according to the load of the hydraulic device that supplies oil.

  1 to 3 show 100% operation of the variable displacement gear pump. The electromagnet 64 is in a non-energized state, and the spool valve 55 is in a position moved backward by a compression spring 59. Therefore, the annular groove 57 communicates with the through hole 61 and the groove 62, and the spool valve 44 of the on-off valve 42 closes the bypass passage 32 by the pressure of the discharge oil.

  In this state, when the driving shaft 6 is given a driving force from the outside, the first driving gear 9 and the second driving gear 10 rotate counterclockwise as shown by arrows in FIG. The first driven gear 11 and the second driven gear (not shown) that mesh with the second drive gear 10 rotate in the clockwise direction. Due to the rotation of each gear, the low-pressure oil in the suction passage 21 flows from the suction side space 22 of the main pump 30 to the first gear chamber 13 and from the suction side space 23 of the sub pump 31 to the second gear chamber 14. Inhaled.

  The oil sucked into the first gear chamber 13 is a space formed between the teeth of the first drive gear 9 and the inner peripheral surface of the first gear chamber 13 and between the teeth of the first driven gear 11 and the first gear chamber. Each of them is confined and transported in a space formed by the inner peripheral surface of 13 and discharged to the discharge side space portion 26. The oil sucked into the second gear chamber 14 is a space formed between the teeth of the second drive gear 10 and the inner peripheral surface of the second gear chamber 14 and between the teeth of the second driven gear (not shown). Each of the second gear chambers 14 is transported while being confined in a space formed by the inner peripheral surface of the second gear chamber 14 and discharged to the discharge-side space 27. Since the oil discharged to the discharge side spaces 26 and 27 merges into the common discharge passage 28 and is supplied from the discharge port 29 to the external hydraulic circuit (not shown), an external hydraulic circuit or a hydraulic device (not shown) is provided. ), The discharge pressure is increased according to the load.

  A part of the oil flowing from the discharge side space portion 26 to the discharge port 29 through the discharge passage 28 flows from the communication hole 39 and the through holes 38 and 37 to the internal space of the valve body 35. Urges the valve body 35 in the closing direction. On the other hand, the oil discharge pressure flowing from the discharge side space 27 to the discharge passage 28 and the pressure generated by the pressure loss of the oil flow accompanying the closing of the bypass passage 32 are applied in the direction of opening the valve body 35 of the check valve 33. Therefore, the pressure balance of the valve body 35 is maintained by the contraction of the compression spring, and the check valve 33 is maintained in the open state.

  Part of the oil in the discharge passage 28 flows through the discharge pressure communication passage 63, and passes through the groove 62, the annular groove 57, the through hole 61, and the gap 67 as the throttle passage through the annular groove 51 and the through hole 52 of the spool valve 44. Into the internal space 50. Therefore, the valve portion 46 of the spool valve 44 is brought into contact with the valve seat 48 by the oil discharge pressure, and the on-off valve 42 maintains the closed state of the bypass passage 32. Accordingly, the oil discharged from the sub pump 31 to the discharge side space 27 flows into the discharge passage 28 and merges with the oil discharged from the main pump 30 to the discharge side space 26, so that 100% of the oil is discharged from the discharge port 29. To an external hydraulic circuit (not shown).

  FIG. 4 shows the state of the variable displacement gear pump during 50% operation. Switching from 100% operation to 50% operation is performed by energizing the electromagnet 64 of the electromagnetic pilot valve 41. Therefore, the spool valve 55 is moved to the front position against the urging force of the compression spring 59, and the annular groove 56 is communicated with the through hole 61. Therefore, the oil in the internal space 50 of the spool valve 55 and the valve hole 43 flows out to the bypass passage 32 via the suction pressure communication passage 58, and the internal space 50 and the valve hole 43 are in a low pressure state.

  The spool valve 44 receives the oil discharge pressure in the bypass passage 32 parallel to the drive shaft 6 and moves rearward, and the valve portion 46 is separated from the valve seat 48. Therefore, the oil discharged to the discharge side space portion 27 is The flow starts to the bypass passage 32 side. Due to the decrease in pressure loss accompanying the opening of the bypass passage 32, the compression spring 36 of the check valve 33 extends, and the valve body 35 moves in the direction of closing the discharge passage 28. Since the oil flowing to the bypass passage 32 is limited to the flow rate set by the bypass passage restricting portion 49, the backflow of the oil discharged from the main pump 30 toward the bypass passage 32 is suppressed.

  The flow restriction of the oil flowing into the bypass passage 32 is continued until the check valve 33 closes the discharge passage 28. For this reason, there is almost no backflow of oil until the check valve 33 is closed, and the occurrence of oil hammer is prevented. When the discharge passage 28 is closed by the check valve 33 and the bypass passage 32 is fully opened, all of the oil discharged from the sub pump 31 flows to the suction passage 24. Therefore, only the oil discharged from the main pump 30 is supplied to the external hydraulic circuit (not shown), and the fluid supply amount is reduced.

  When switching the variable displacement gear pump from 50% operation to 100% operation, the electromagnet 64 of the electromagnetic pilot valve 41 is deenergized. The electromagnet 64 is demagnetized, the spool valve 55 is moved rearward by the compression spring 59, and the annular groove 57 communicates with the through hole 61 and the groove 62 (see FIG. 5). The oil discharged from the discharge passage 28 flows from the discharge pressure communication passage 63 into the internal space 50 of the spool valve 44 through the groove 62, the annular groove 57, the through hole 61 and the annular groove 51. Accordingly, the spool valve 44 moves forward at a constant speed by the oil discharge pressure. As the spool valve 44 moves, resistance occurs in the oil flow to the bypass passage 32, so that the pressure loss in the bypass passage 32 parallel to the drive shaft 6 increases, and the valve body 35 of the check valve 33 moves in the opening direction. (See FIG. 6).

  When the spool valve 44 moves to the end stage of the closing operation of the on-off valve 42, the annular groove 51 of the spool valve 44 is released from the communication state with the through hole 61. The discharged oil that has flowed into the through hole 61 is supplied to the annular groove 51 through a gap 67 that is configured as a throttle passage (see FIG. 7). For this reason, the amount of oil supplied to the internal space 50 decreases, and the moving speed of the spool valve 44 is greatly reduced. The spool valve 44 moves forward while maintaining the deceleration state due to the throttle effect of the gap 67, and the valve portion 46 of the spool valve 44 contacts the valve seat 48 at a slow speed to complete the closing operation of the bypass passage 32. (See FIGS. 1 and 3).

  Accordingly, since the amount of oil flowing through the bypass passage 32 toward the suction passage 24 is gradually reduced, it is possible to prevent the occurrence of an impact or noise associated with the impact as when the bypass passage 32 is suddenly closed. . Further, since the valve portion 46 of the spool valve 44 contacts the valve seat 48 at a slow speed, it is possible to prevent the occurrence of impact and contact noise due to contact.

  When the bypass passage 32 is closed and the discharge passage 28 is opened, the oil discharged from the sub-pump 31 merges with the discharge passage 28, and together with the oil discharged from the main pump 30, an external hydraulic circuit (see FIG. Not shown). The bypass passage throttle 49 provided on the front end side of the spool valve 44 has a throttle function for the discharged oil flowing through the bypass passage 32 as the spool valve 44 moves in the closing direction. Therefore, in the present embodiment, the throttling function of the bypass passage throttling portion 49 can be used together with the throttling function of the gap 67 of the spool valve 44, so that the effect of preventing impact and noise generation can be further enhanced.

The first embodiment described above has the following operational effects.
(1) Since the supply of the discharge oil is limited by using the sliding gap 67 of the spool valve 44 at the end stage of the closing operation of the on-off valve 42, the moving speed of the spool valve 44 is slowed down so that the bypass passage 32 In addition, it is possible to prevent the occurrence of impacts and noises associated with such closing, and to easily configure the throttle passage.
(2) Since the opening and closing port of the check valve 33 is performed by pressure balance, a compression spring having a small spring constant can be used, and the configuration can be simplified and downsized.
(3) By preventing the occurrence of impact and noise associated with the closing of the bypass passage 32, an effect of preventing the vibration of the compression spring 36 of the check valve 33 can be expected. That is, when vibration of the compression spring 36 occurs at the closing timing of the check valve 33, the valve body 35 repeats the closing position and the opening position, thereby causing an unstable state. For this reason, the oil on the main pump 30 side repeats backflow and backflow stop, and there is a risk of obstructing a fixed amount of oil supply to an external hydraulic circuit (not shown), resulting in an unstable state. However, the vibration generation preventing effect of the compression spring 36 can eliminate such a problem.
(4) By using the throttling function by the throttling portion 49 for the bypass passage in combination, the change in the amount of oil flowing through the bypass passage 32 can be made smoother.

(Second Embodiment)
The second embodiment shown in FIG. 8 is obtained by changing the shape of the gap 67 that forms the throttle passage in the first embodiment. The same reference numerals are given to the same components as those in the first embodiment, and Detailed description is omitted. In the second embodiment, when the on-off valve 42 closes the bypass passage 32, a part of the inner wall surface of the valve hole 43 is engraved in a frustoconical shape that expands from the annular groove 51 side to the through hole 61 side. The throttle passage 68 is formed. In other words, the throttle passage 68 has a tapered surface on the rear housing 4 side. Therefore, as the spool valve 44 moves forward, the throttle amount gradually increases, so that the moving speed of the spool valve 44 can be gradually decreased. Such a configuration of the throttle passage 68 is also effective in the case where the sliding clearance of the spool valve 44 is very narrow and the oil supply amount is excessively throttled. The tapered cross section may be configured to be connected to the annular groove 51 on the outer peripheral surface side of the spool valve 44, or may be configured to be formed on both the spool valve 44 and the rear housing 4.

(Third embodiment)
The third embodiment shown in FIG. 9 is obtained by changing the shape of the gap 67 that forms the throttle passage in the first embodiment. The same reference numerals are given to the same components as those in the first embodiment. Detailed description is omitted. In the third embodiment, in the state where the on-off valve 42 closes the bypass passage 32, a part of the inner wall surface of the valve hole 43 is expanded on the rear housing 4 side from the annular groove 51 side to the through hole 61 side. The throttle passage 69 is configured by forming a stepped surface having a stepped cross section. Therefore, as the spool valve 44 moves forward, the throttle amount is gradually increased but gradually increased, and the moving speed of the spool valve 44 can be gradually decreased. The third embodiment has the same function and effect as the second embodiment. The step-like surface in section can be formed on the outer peripheral surface side of the spool valve 44 so as to be connected to the annular groove 51, or can be formed on both the spool valve 44 and the rear housing 4.

  The present invention is not limited to the configuration of each of the embodiments described above, and various modifications are possible within the scope of the gist of the present invention, and can be implemented as follows.

(1) The throttle passage can be formed in any one of the discharge pressure communication passage 63, the groove 62, the annular groove 57, and the through hole 61 constituting the oil supply passage. For example, a method of forming the annular groove 57 shallow, or a method of forming the through hole 61 as a dedicated fluid supply hole with a small diameter is conceivable. However, in these methods, since the moving speed of the spool valve 44 toward the closing side becomes slow from beginning to end, it is preferable to set the maximum opening amount of the spool valve 44 as small as possible.
(2) The spool valve 44 in the first embodiment is configured to form a bypass passage throttle portion 49 between the inner wall surface of the bypass passage 32 by providing a cylindrical portion 47 on the front end side. The throttle part 49 for bypass passage is not necessarily required.
(2) The electromagnetic pilot valve 41 that operates the on-off valve 42 may be configured to operate by differential pressure instead of the electromagnetic type.
(3) The on-off valve 42 does not use the electromagnetic pilot valve 41 and operates by directly connecting to an oil passage through a switching valve between the discharge pressure on the discharge passage 28 side and the low pressure on the suction passages 21 and 24 side. You may comprise.
(4) The variable displacement rotary pump is not limited to a gear pump, and can be implemented in other pumps such as a screw pump, a vane pump, and a roots pump.

It is a longitudinal cross-sectional view of the gear pump which shows 1st Embodiment. It is the sectional view on the AA line of FIG. It is an expanded sectional view showing an on-off valve. It is sectional drawing which shows the relationship between the non-return valve at the time of 50% driving | operation, and an on-off valve. It is sectional drawing which shows the relationship between the non-return valve at the time of switching to a 100% driving | operation, and an on-off valve. It is sectional drawing which shows the relationship between the non-return valve at the time of switching to a 100% driving | operation, and an on-off valve. It is sectional drawing which shows the relationship between the non-return valve at the time of switching to a 100% driving | operation, and an on-off valve. It is a fragmentary sectional view of the on-off valve which shows 2nd Embodiment. It is a fragmentary sectional view of the on-off valve which shows a 3rd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 6 Drive shaft 7 Driven shaft 9 1st drive gear 10 2nd drive gear 11 1st driven gear 13 1st gear chamber 14 2nd gear chamber 21, 24 Suction passage 22, 23 Suction side space part 26, 27 Discharge side Space portion 28 Discharge passage 29 Discharge port 30 Main pump 31 Sub pump 32 Bypass passage 33 Check valve 41 Electromagnetic pilot valve 42 On-off valve 44 Bypass valve body 47 Column portion 49 Bypass passage throttle portion 55 Spool valve 58 Suction pressure communication passage 63 Discharge pressure communication passage 67 Clearance (throttle passage)

Claims (7)

A main pump, a sub pump, a check valve disposed in a discharge passage for supplying discharge fluid of the sub pump to the outside, and an on-off valve provided in a bypass passage for returning the discharge fluid of the sub pump to the suction side In the variable displacement rotary pump that changes the amount of fluid supplied to the outside by different opening and closing port operations of the check valve and the on-off valve,
A fluid supply passage that operates in a direction to close the on-off valve is connected to the on-off valve, and a throttle passage that acts at least at the end stage of the closing operation of the on-off valve is disposed in the fluid supply passage. Variable displacement rotary pump.   The on-off valve is slidably disposed in the valve hole, and is configured by a spool valve that moves between a position that contacts a valve seat formed in a part of the bypass passage and a position that is separated from the valve seat. 2. The variable displacement type according to claim 1, wherein the throttle passage is configured as a gap for sliding the spool valve formed between an outer peripheral surface of the spool valve and an inner wall surface of the valve hole. Rotary pump.   3. The variable displacement rotary pump according to claim 1, wherein the throttle passage has a configuration in which a throttle amount is gradually increased until the on-off valve closes the bypass passage. 4.   The variable displacement rotary pump according to claim 3, wherein at least a part of the throttle passage has a tapered cross section.   The variable displacement rotary pump according to claim 3, wherein at least a part of the surface of the throttle passage is a stepped surface having a stepped cross section.   The variable displacement rotary pump according to any one of claims 1 to 5, wherein the on-off valve is operated by a pilot valve.   The variable displacement rotary pump according to any one of claims 1 to 6, wherein the rotary pump is a gear pump.