JP2015194134A - Triple gear pump and fluid supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply an appropriate pressing force in an opposite direction to a floating bearing of a triple gear pump even if a floating force generated in the floating bearing of the triple gear pump changes with a change in a connection state of first and second gear pumps.SOLUTION: In a connection state in which a first gear pump 11 and a second gear pump 13 are connected in parallel, a low-pressure receiving surface 15d and a switched-pressure receiving surface 15e of a floating bearing 15a serve as a receiving surface for receiving a non-boosted fuel pressure (low pressure) and only a high-pressure receiving surface 15c serves as a boosted-fuel-pressure (high-pressure) receiving surface. In a connection state in which the first gear pump 11 and the second gear pump 13 are connected in series, only the low-pressure receiving surface 15d serves as the low-pressure receiving surface and the high-pressure receiving surface 15c and the switched-pressure receiving surface 15e serve as the high-pressure receiving surface. In this way, area rates of the low-pressure receiving surface and the high-pressure receiving surface are changed depending on the connection state of the first gear pump 11 and the second gear pump 13, and a pressing force Fp in an opposite direction is changed depending on a change in a floating force Ff generated in the floating bearing 15a of a drive gear 5.

Description

  The present invention relates to a triple gear pump in which two driven gears are meshed with one drive gear, and a gear pump for boosting fluid is constituted by a set of each driven gear and drive gear, and a fluid supply device using the triple gear pump .

  Gear pumps are frequently used when boosting a low-viscosity fluid such as aircraft fuel. The pressure increase of the fluid by the gear pump is performed in a space formed by the drive gear, the driven gear, and the housing. The discharge amount of the fluid boosted by the gear pump is proportional to the rotational speed of the drive gear in an ideal state where there is no leakage.

  In particular, a gear pump that supplies fuel to an aircraft engine uses a gear box as an engine accessory that is driven to rotate by a rotational force transmitted from the engine as a power source. For this reason, the fuel supplied by the gear pump is proportional to the engine speed.

  On the other hand, the amount of fuel consumed by an aircraft engine is greatly reduced when cruising in the high sky compared to takeoff. Therefore, in order to prevent excessive fuel from being supplied in proportion to the rotational speed of the engine during cruise of the engine, the present applicant meshes two driven gears with one drive gear, and each driven gear and the drive gear. In the past, we proposed a triple gear pump that each comprised a gear pump.

  In this triple gear pump, two gear pumps are connected in parallel at takeoff, so that the fuel discharged from each gear pump can be summed and supplied to the engine. Further, by connecting two gear pumps in series during cruising, the amount of fuel supplied to the engine can be reduced to the discharge amount of one gear pump.

  By the way, on the side surfaces of the drive gear and the driven gear of the gear pump, a floating force is generated in such a direction that the bearings are lifted from the drive gear and the driven gear in the direction of the rotation center axis by the pressure of the fluid that circulates from the tip side of the teeth. This floating force creates a gap allowing the fluid leakage flow between the side surface of the drive gear or the driven gear and the bearing surface, and causes the fluid discharge amount to deviate from the design value.

  Therefore, also in the above-described triple gear pump, a bearing on one end side in the rotation center axis direction among the bearings of each gear is a floating bearing that can move in the rotation center axis direction, and a fluid is provided on the end surface in the rotation center axis direction of the floating bearing. Pressure is applied so that the floating bearing presses each gear against the fixed bearing side on the other end side in the direction of the rotation center axis.

  Specifically, two pressure receiving surfaces are provided on the floating bearings of each gear, and the fluid pressure at the inlet of the triple gear pump (low pressure before pressure increase) and the fluid pressure at the outlet (high pressure after pressure increase) are respectively applied to each pressure receiving surface. Yes. In each floating bearing, by adjusting the pressure receiving area of each pressure receiving surface according to the floating force generated in the bearing, the force for pressing the bearing gear against the fixed bearing side by the floating bearing (pressing force) is optimized. .

  In the triple gear pump, in particular, the floating force generated on the side surface of the driven gear on the second pump side is greatly different between the case where the first and second gear pumps are connected in parallel and the case where they are connected in series.

  That is, the inlet of the second gear pump is connected to the inlet of the first gear pump when connected in parallel, and is connected to the outlet of the first gear pump when connected in series. The fluid pressure at the inlet of the first gear pump becomes a low pressure before the pressure increase, and the fluid pressure at the outlet becomes a high pressure after the pressure increase. For this reason, the fluid pressure at the inlet of the second gear pump is a low pressure before boosting when connected in parallel, and a high pressure after boosting when connected in series.

  As described above, the fluid pressure at the inlet of the second gear pump, which is different between when connected in parallel and when connected in series, is one of the factors that determine the floating force of the floating bearing of the driven gear on the second pump side. Join the side. Therefore, as described above, the floating force of the floating bearing of the driven gear on the second pump side is greatly different between the parallel connection and the series connection as well as the fluid pressure at the inlet of the second gear pump.

  Therefore, in the triple gear pump described above, one of the pressure receiving surfaces provided on the floating bearing of the driven gear on the second pump side is replaced with the fluid pressure at the outlet of the triple gear pump that becomes high pressure in parallel connection and series connection. Thus, the fluid pressure on the inlet side of the second gear pump, which is low when connected in parallel and high when connected in series, is applied.

  Thereby, when the connection state of the first and second gear pumps is switched between the parallel connection and the series connection, according to the change of the floating force applied to the side surface of the floating bearing of the driven gear on the second pump side, The force with which the floating bearing presses the driven gear on the second pump side against the fixed bearing side is changed (for example, Patent Document 1).

JP 2003-328958 A

  In recent years, the fuel supply pressure required in aircraft engines has been increasing, and accordingly, it is expected that the floating force applied to the side of the floating bearing of each gear of the triple gear pump will also increase. In that case, the ratio of the pressure receiving surface that receives the pressure of the fluid after pressure increase provided in the floating bearing of each gear is increased. Thereby, the pressing force of the floating bearing can be increased to counter the increased floating force of the floating bearing.

  In particular, in the drive gear, the magnitude of the floating force when the first and second gear pumps are connected in series, at which the floating force of the floating bearing is maximized, becomes higher as the fuel supply pressure increases. For this reason, in the floating bearing of the drive gear, it is conceivable to increase the ratio of the pressure receiving surface that receives the pressure of the fluid after the pressure increase based on the floating force of the floating bearing when the first and second gear pumps are connected in series.

  Further, in the drive gear, the floating force of the floating bearing is maximized when the high pressure after the pressure increase is applied to the side surface as the fluid pressure at the inlet of the second gear pump. For this reason, in the floating bearing of the drive gear, it is conceivable to increase the ratio of the pressure receiving surface that receives the pressure of the fluid after the pressure increase based on the floating force of the floating bearing when the first and second gear pumps are connected in series.

  However, by doing so, when the first and second gear pumps are connected in parallel, where the low pressure before the pressure increase is applied to the side surface of the floating bearing of the drive gear as the fluid pressure at the inlet of the second gear pump, the floating force of the floating bearing at that time is reduced. In view of the low level, the ratio of the pressure receiving surface that receives the pressure of the fluid after the pressure increase may become excessive. That is, the pressing force that the floating bearing applies to the drive gear due to the fluid pressure applied to each pressure receiving surface of the floating bearing when the first and second gear pumps are connected in parallel may be excessive with respect to the floating force of the floating bearing of the drive gear. There is.

  An excessive pressing force of the drive gear by the floating bearing is not preferable for smoothly rotating the drive gear when the first and second gear pumps are connected in parallel.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reverse the direction even if the floating force generated in the floating bearing of the triple gear pump is changed by switching the connection state of the first and second gear pumps. An object of the present invention is to provide a triple gear pump capable of applying a pressing force to a floating bearing with an appropriate size, and a fluid supply device using the triple gear pump.

In order to achieve the above-mentioned object, a triple gear pump according to the present invention described in claim 1 is provided.
A triple gear pump having a first gear pump and a second gear pump capable of switching connection states in parallel and in series,
One drive gear common to the first gear pump and the second gear pump;
Two driven gears respectively corresponding to the first gear pump and the second gear pump and individually meshed with the drive gear;
Each of the gears is supported by bearing one end of the rotation shaft of each of the drive gear and each driven gear, and receiving the pressure before and after the pressure increase by the first gear pump and the second gear pump at the respective pressure receiving surfaces. Floating bearings that are respectively pressed to the side and are movable in the direction of the central axis of each rotary shaft;
A fixed bearing that is non-movable in the direction of the central axis of each rotary shaft, bearing the other end of the rotary shaft of each of the drive gear and each driven gear;
The floating bearing of the drive gear is provided with an additional pressure receiving surface,
The additional pressure receiving surface is provided by the first gear pump or the second gear pump in a state in which the first gear pump and the second gear pump are connected in parallel by the first gear pump and the second gear pump, respectively. In the serial connection state of the first gear pump and the second gear pump, the fluid pressure before the pressure increase is applied and the fluid pressure increased by the first gear pump passes through the second gear pump with the same pressure. The fluid pressure after pressurization is applied,
It is characterized by that.

  A triple gear pump, in which the two driven gears constitute a first gear pump and a second gear pump, respectively, with a pair of driving gears that are common mating counterparts of each driven gear, the first gear pump and the second gear pump are The connection state can be switched between a parallel connection state in which the pressure of each fluid is increased and a series connection state in which the fluid whose pressure is increased by the first gear pump passes through the second gear pump with the same pressure.

  And if the connection state of a 1st gear pump and a 2nd gear pump is switched between parallel and series, the connection partner of the inlet of a 2nd gear pump will switch between the inlet and outlet of a 1st gear pump.

  Here, the fluid pressure at the inlet of the first gear pump is a low pressure before pressure increase, and the fluid pressure at the outlet of the first gear pump is a high pressure after pressure increase. For this reason, the fluid pressure at the inlet of the second gear pump is a low pressure before pressure increase in the parallel connection state of the first gear pump and the second gear pump, and a high pressure after pressure increase in the serial connection state of the first gear pump and the second gear pump.

  Therefore, according to the triple gear pump of the present invention described in claim 1, the additional pressure receiving surface of the floating bearing of the drive gear that receives the fluid pressure at the inlet of the second gear pump is connected in parallel between the first gear pump and the second gear pump. In the state, it becomes a pressure receiving surface for the pressure (low pressure) before the fluid pressure is increased. On the other hand, in the serial connection state of the first gear pump and the second gear pump, the additional pressure receiving surface is a pressure receiving surface for the pressure after increasing the pressure of the fluid (high pressure).

  That is, in the parallel connection state of the first gear pump and the second gear pump, the pressure receiving surface of the pressure (low pressure) before the pressure increase and the additional pressure receiving surface of the existing fluid are the pressure receiving surfaces of the low pressure fluid pressure before the pressure increase, Only the pressure receiving surface of the pressure (high pressure) after the pressure increase of the fluid that originally exists becomes the pressure receiving surface of the high pressure fluid pressure after the pressure increase.

  On the other hand, in the serial connection state of the first gear pump and the second gear pump, only the pressure receiving surface for the pressure (low pressure) before the pressure increase of the existing fluid becomes the pressure receiving surface for the low pressure fluid pressure before the pressure increase. The pressure receiving surface of the pressure (high pressure) after the pressure increase and the additional pressure receiving surface become the pressure receiving surface of the high pressure fluid pressure after the pressure increase.

  Thus, the ratio of the area of the pressure receiving surface of the low-pressure fluid pressure before pressurization and the pressure receiving surface of the high-pressure fluid pressure after pressurization changes between the parallel connection state and the series connection state of the first gear pump and the second gear pump. . Therefore, even if the floating force from the fixed bearing applied to the floating bearing of the drive gear changes due to the switching of the connection state of the first and second gear pumps, the reverse pressing force can be applied to the floating bearing with an appropriate magnitude. it can.

The fluid supply device of the present invention described in claim 2
A device for supplying fluid pressurized by a gear pump to the outside,
A triple gear pump according to claim 1;
A switching unit that switches a connection state between the first gear pump and the second gear pump of the triple gear pump between a parallel connection state and a series connection state;
It is characterized by providing.

  According to the fluid supply device of the present invention described in claim 2, the same effect as the triple gear pump of the present invention described in claim 1 can be obtained.

  Furthermore, the fluid supply device of the present invention described in claim 3 is the fluid supply device of the present invention described in claim 2, wherein the outlet of the first gear pump or the second gear pump is connected to the drive gear of the triple gear pump. A pressure introduction passage connected to an additional pressure receiving surface provided in the floating bearing, a pressure equalization passage connecting the pressure introduction passage to the inlet of the first gear pump, and a connection point of the pressure equalization passage to the pressure introduction passage are opened and closed And a valve opening degree of the on-off valve is changed continuously or stepwise between fully closed and fully open during a transition period from the start to the end of switching of the connection state by the switching unit. It is characterized by that.

  According to the fluid supply device of the present invention described in claim 3, in the fluid supply device of the present invention described in claim 2, the fluid pressure at the outlet of the first gear pump and the fluid pressure at the outlet of the second gear pump are: Regardless of whether the first gear pump and the second gear pump are connected in parallel or in series, the high pressure after boosting is obtained. Therefore, the fluid pressure in the pressure introduction passage is high.

  On the other hand, the fluid pressure at the inlet of the first gear pump is a low pressure before the pressure increase regardless of whether the connection state of the first gear pump and the second gear pump is in parallel or in series. Therefore, the fluid pressure in the pressure equalizing passage is low.

  And when a switching part switches the connection state of a 1st gear pump and a 2nd gear pump between parallel and series, in the transition period from the start to completion | finish, the on-off valve of the connection location of the equalization passage with respect to a pressure introduction passage The valve opening is continuously or stepwise changed between fully closed and fully open.

  Therefore, when the connection state of the first gear pump and the second gear pump is switched from parallel to serial, the fluid guided to the additional pressure receiving surface of the floating bearing of the drive gear through the pressure introduction passage during the transition period from the start to the end. The pressure changes continuously or stepwise from low pressure to high pressure. On the other hand, when the connection state of the first gear pump and the second gear pump is switched from serial to parallel, it is guided to the additional pressure receiving surface of the floating bearing of the drive gear through the pressure introduction passage in the transition period from the start to the end. The fluid pressure changes continuously or stepwise from high pressure to low pressure.

  For this reason, during the transition period in which the connection state of the first gear pump and the second gear pump is switched, the fluid pressure at the inlet of the second gear pump increases or decreases between the low pressure before the pressure increase and the high pressure after the pressure increase. Even if the floating force generated in the floating bearing changes, the pushing force applied to the floating bearing is changed in the opposite direction to the floating force in synchronization with the change, so that the floating force is always in an appropriate size and in the direction opposite to the floating force. A pressing force can be applied to the floating bearing.

  According to the present invention, even if the floating force generated in the floating bearing of the triple gear pump is changed by switching the connection state of the first and second gear pumps, the pressing force in the reverse direction is applied to the floating bearing with an appropriate magnitude. be able to.

It is explanatory drawing which shows the arrangement | sequence of the drive gear of the triple gear pump which concerns on one Embodiment of this invention, and a driven gear. It is the sectional view on the AA line of FIG. It is an explanatory view at the time of making a triple gear pump into a parallel connection state, showing an example of an aircraft fuel supply device using the triple gear pump of FIG. 1 for pressurization. It is explanatory drawing which shows schematic structure of the nozzle flapper mechanism of FIG. 3, and its drive circuit. It is explanatory drawing at the time of making the triple gear pump of FIG. 3 into a serial connection state. It is an expanded sectional view of the bearing part by the drive gear of FIG. 2, a driven gear, and those floating bearings. (A) is explanatory drawing which shows typically the distribution of the fuel pressure in the side surface of the drive gear of the parallel connection state shown in FIG. 3, (b) is a graph which shows the distribution by the relationship with the phase in the rotation direction of a drive gear. is there. (A) is explanatory drawing which shows typically the distribution of the fuel pressure in the side surface of the drive gear of the serial connection state shown in FIG. 5, (b) is a graph which shows this distribution by the relationship with the phase in the rotation direction of a drive gear. is there. It is explanatory drawing which shows the fuel pressure added to the pressure receiving surface of each floating bearing in the parallel connection state shown in FIG. It is explanatory drawing which shows the fuel pressure added to the pressure receiving surface of each floating bearing in the serial connection state shown in FIG. It is explanatory drawing at the time of setting a triple gear pump to the parallel connection state which shows the other example of the aviation fuel supply apparatus which used the triple gear pump of FIG. 1 for pressure | voltage rise based on other embodiment of this invention. It is explanatory drawing at the time of setting the triple gear pump of FIG. 11 to the serial connection state.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The triple gear pump 1 of the present embodiment shown in the explanatory view of FIG. 1 has one drive gear 5 housed inside the housing 3 and first and second driven gears 7 and 9 meshing with the drive gear 5. doing. The pair of driven gears 7 and 9 and the drive gear 5 constitute the first and second gear pumps 11 and 13.

  The drive gear 5, the first driven gear 7, and the second driven gear 9 are meshed with each other in the housing 3. The fluids flowing between the first suction port 11a and the second suction port 13a of the housing 3 between the gears 5 and 7 and the teeth 5a and 7a (9a) of the gears 5 and 9 are adjacent to each other as the gear rotates. The pressure is increased by being confined in the space surrounded by the teeth and the wall surface of the housing 3, and the pressure is increased to move to the first discharge port 11 b and the second discharge port 13 b.

  That is, the triple gear pump 1 has a first gear pump 11 mainly composed of the drive gear 5 and the first driven gear 7 and a second gear pump 13 mainly composed of the drive gear 5 and the second driven gear 9. It has a structure.

  The first driven gear 7 and the second driven gear 9 have the same size, and the first gear pump 11 and the second gear pump 13 have the same discharge flow rate with respect to the rotational speed of the drive gear 5. In addition, as a tooth profile of each gear, it is not limited to a flat tooth, a helical tooth, etc. Various tooth profiles, such as a sine curve and a trochoid curve, are applicable.

  As shown in FIG. 2 which is a cross-sectional view taken along line AA of FIG. 1, the drive shaft 5 and the first and second driven gears 7, 9 on the left rotation shafts 5b, 7b, 9b (one end in the claims). Is supported by floating bearings 15a, 17a, 19a supported by the housing 3 so as to be movable in the direction of the rotation center axis (left-right direction in FIG. 2). Further, the right rotation shafts 5c, 7c and 9c (corresponding to the other end in the claims) of the drive gear 5 and the first and second driven gears 7 and 9 in the drawing are fixed to the housing 3 in the direction of the rotation center axis. The bearings 15b, 17b and 19b are immovable.

  The first gear pump 11 and the second gear pump 13 of the triple gear pump 1 described above are configured to be able to switch connection states in parallel and in series. In the parallel connection state, the first suction port 11a and the second suction port 13a shown in FIG. 1 are connected, and the first discharge port 11b and the second discharge port 13b are connected. In the serial connection state, the first discharge port 11b of the first gear pump 11 and the second suction port 13a of the second gear pump 13 are connected.

  FIG. 3 is an explanatory diagram showing an example of a fuel supply device for an aircraft (not shown) that uses the triple gear pump 1 of FIG. 1 for boosting. In the fuel supply device 20 (corresponding to the fluid supply device in the claims), the low-pressure fuel (fluid) boosted by the boost pump 21 is boosted by the first gear pump 11 and the second gear pump 13 and is not shown. It is supplied to an engine nozzle (corresponding to the outside in the claims).

  Specifically, the low-pressure fuel after the boost is supplied to the first suction port 11a of the first gear pump 11 through the first supply path 23a. A second supply path 23 b branched from the first supply path 23 a is connected to the second suction port 13 a of the second gear pump 13. The second supply path 23b is provided with a check valve 23c that prevents the fuel from flowing back to the first supply path 23a.

  A first discharge path 25 a is connected to the first discharge port 11 b of the first gear pump 11, and a second discharge path 25 b is connected to the second discharge port 13 b of the second gear pump 13. The first discharge path 25a and the second discharge path 25b are connected to an engine nozzle (not shown). Therefore, the fuel supply device 20 of FIG. 3 is in a state where the first gear pump 11 and the second gear pump 13 are connected in parallel. In this state, the check valve 23c is opened to allow fuel to pass from the first supply path 23a to the second supply path 23b.

  The first discharge path 25a is connected to the primary side of the differential pressure type on / off valve 27, and the secondary side of the differential pressure type on / off valve 27 is connected to the second supply path 23b. The valve body 27a of the differential pressure type on-off valve 27 is urged toward the valve closing side that shuts off the primary side and the secondary side by a spring 27c accommodated in the spring chamber 27b. The primary side of the differential pressure type open / close valve 27 and the spring chamber 27b are connected by a pressure equalizing passage 27d.

  A nozzle 27e is provided in the pressure equalizing passage 27d, and an orifice 27f is provided at a location on the primary side of the differential pressure type on-off valve 27 with respect to the nozzle 27e of the pressure equalizing passage 27d. The nozzle 27e of the pressure equalizing passage 27d extends into the low pressure chamber 29 connected to the first supply path 23a. The low pressure chamber 29 is provided with a nozzle-flapper mechanism 31. When the nozzle 27 e is closed, the internal pressure of the spring chamber 27 b is equalized to the same pressure as the internal pressure of the first discharge path 25 a connected to the primary side of the differential pressure type on-off valve 27.

  The nozzle-flapper mechanism 31 has a torque motor 33 as shown in the explanatory view of FIG. The torque motor 33 includes a pair of permanent magnets 33a and 33b having a magnetic pole facing the tip, and an armature 33d provided between the magnetic poles of the permanent magnets 33a and 33b so as to be rotatable about a rotation axis 33c. The coil 33e and 33f are wound around the armature 33d.

  The nozzle-flapper mechanism 31 has a flapper 35 that is driven by a torque motor 33. The flapper 35 is connected so as to be orthogonal to the armature 33d, and is rotatably supported by the rotation shaft 33c. Further, the flapper 35 is biased by a torsion spring (not shown) provided on the rotation shaft 33c so that the armature 33d is horizontal (so that the flapper 35 extends in the vertical direction).

  A current is supplied to the coil 33e by the first current driver 37, and a current is supplied to the coil 33f by the second current driver 39. Each of the first current driver 37 and the second current driver 39 generates a current corresponding to the operation amount of the armature 33d input from the motor control unit 41. Normally, only the first current driver 37 operates, and the second current driver 39 operates when the first current driver 37 fails.

  Here, when a current is supplied from the first current driver 37 to the coil 33e, a torque corresponding to the supplied current is generated in the torque motor 33, the armature 33d rotates, and the flapper 35 follows the rotation of the armature 33d. It swings and is displaced in the direction of the nozzle 27e. The flapper 35 stops at a position where a rotational torque acting on the armature 33d and a reaction force by a torsion spring (not shown) are balanced. As a result, the nozzle-flapper mechanism 31 opens the nozzle 27e at an opening degree corresponding to the amount of displacement of the flapper 35, and connects the low pressure chamber 29 and the pressure equalizing passage 27d in FIG.

  The opening / closing operation of the nozzle 27e by the nozzle-flapper mechanism 31 using the torque motor 33 is feedback-controlled based on the displacement amount of the flapper 35 detected by a sensor (not shown). Specifically, for example, a physical quantity generated by the displacement of the flapper 35 is detected by a sensor and fed back to the motor control unit 41, and a deviation from the target displacement amount of the flapper 35 is calculated by the motor control unit 41. Then, the motor control unit 41 multiplies the calculated deviation by a proportional gain constant to calculate the operation amount (supply current) of the torque motor 33 according to the target displacement amount of the armature 33d to the flapper 35, and the first current driver 37 (or the second current driver 39).

  As described above, the current supplied to the torque motor 33 is feedback-controlled, so that the actual displacement amount of the armature 33d to the flapper 35 is controlled to coincide with the target displacement amount, and the opening of the nozzle 27e by the flapper 35 is controlled. The degree is controlled.

  When the nozzle 27e is opened by the flapper 35 of the nozzle-flapper mechanism 31, the internal pressure on the nozzle 27e side (the spring chamber 27b side of the differential pressure on-off valve 27) from the orifice 27f of the pressure equalizing passage 27d and the orifice of the pressure equalizing passage 27d. A pressure difference is generated between the internal pressure on the primary chamber side (the first discharge path 25a side of the fuel supply device 20) of the differential pressure type on-off valve 27 with respect to 27f.

  Specifically, on the nozzle 27e side of the pressure equalizing passage 27d from the orifice 27f, the fuel in the first discharge passage 25a pressurized by the first gear pump 11 in FIG. 3 is pressurized by the first gear pump 11 by the orifice 27f. The pressure is reduced to about the fuel pressure in the previous first supply path 23a and flows in. Therefore, the fuel pressure on the primary chamber side of the pressure equalizing passage 27d across the orifice 27f becomes high, and the fuel pressure on the nozzle 27e side becomes low.

  Thus, when the fuel pressure on the spring chamber 27b side becomes lower than the primary chamber side on the differential pressure type on-off valve 27, the valve body 27a is primary against the urging force of the spring 27c as shown in the explanatory view of FIG. The valve is opened by the fuel pressure in the chamber, and the first discharge path 25 a and the second supply path 23 b are connected via the differential pressure type on-off valve 27. That is, the first discharge port 11b of the first gear pump 11 and the second suction port 13a of the second gear pump 13 are connected, and the fuel supply device 20 of FIG. 5 includes the first gear pump 11 and the second gear pump 13 in series. Connected.

  In the state of FIG. 5 in which the first gear pump 11 and the second gear pump 13 are connected in series, the fuel pressure in the second supply path 23 b becomes a high pressure after being boosted by the first gear pump 11. Therefore, the second gear pump 13 does not substantially perform the fuel boosting operation, and passes through the fuel boosted by the first gear pump 11 as it is.

  In the state of FIG. 5 in which the first gear pump 11 and the second gear pump 13 are connected in series, the fuel pressure in the second supply path 23b becomes high, and the check valve 23c in the second supply path 23b is closed. Therefore, the backflow of the high-pressure fuel from the second supply path 23b to the first supply path 23a is prevented.

  3 and 5 is a relief valve interposed between the first supply path 23a and the second discharge path 25b. In this relief valve 43, the pressure of the fuel in the second discharge path 25b, which is contained due to a malfunction of a fuel metering mechanism (not shown) installed at the rear stage of the triple gear pump 1, is reduced by a spring (see FIG. (Not shown), the valve is opened by the fuel pressure in the second discharge passage 25b.

  As apparent from the above description, in the present embodiment, the differential pressure type on-off valve 27, the pressure equalizing passage 27d, the low pressure chamber 29, the nozzle-flapper mechanism 31, the torque motor 33, the flapper 35, etc. The switching unit is configured.

  By the way, in the triple gear pump 1, when the fuel passes through the first and second gear pumps 11, 13, the teeth 5a, 7a, 9a of the drive gear 5 and the first and second driven gears 7, 9 are used. Some fuel wraps around the side. Therefore, the side surfaces of the teeth 5a, 7a, 9a serve as pressure receiving surfaces for the fluid pressure of the fuel that wraps around the teeth.

  The floating bearing 15a of the drive gear 5 and the floating bearings 17a and 19a of the first and second driven gears 7 and 9 are driven by the fluid pressure of the fuel applied to the pressure receiving surface, as shown in the explanatory view of FIG. In the axial direction of 7c, 9c, a floating force Ff in the direction of floating (separating) from the drive gear 5 and the first and second driven gears 7, 9 is received.

  When the floating bearings 15a, 17a, and 19a float from the drive gear 5 and the first and second driven gears 7 and 9, and a gap is formed between them, each of the first and second is caused by the fuel leakage flow from the gap. The gear pumps 11 and 13 cannot discharge the fuel as designed.

  In view of this, a portion of the floating bearings 15a, 17a, 19a facing the housing 3 is provided with a pressure receiving surface for the fluid pressure of the fuel that has entered the gap with the housing 3. A pressing force Fp that opposes the above-described floating force Ff is applied to the floating bearings 15a, 17a, and 19a by the fluid pressure of the fuel applied to the pressure receiving surface.

  It is desirable that the pressing force Fp is slightly higher than the floating force Ff. If the pressing force Fp is too low, the floating bearings 15a, 17a, 19a cannot be prevented from floating from the drive gear 5 and the first and second driven gears 7, 9. On the other hand, if the pressing force Fp is too high, the drive gear 5 and the first and second driven gears 7 and 9 are excessively pressed against the fixed bearings 15b, 17b, and 19b, causing friction during rotation and causing seizure or the like. It becomes a factor that the trouble occurs.

  Therefore, the pressure receiving surfaces provided in the portions of the floating bearings 15a, 17a, 19a facing the housing 3 are shaped so that a pressing force Fp slightly exceeding the floating force Ff generated in the floating bearings 15a, 17a, 19a is generated. Is set to Hereinafter, the pressure receiving surfaces of the floating bearings 15a, 17a, and 19a will be described.

  First, the pressure receiving surfaces of the floating bearings 17a and 19a corresponding to the first and second driven gears 7 and 9 will be described.

  First, the fuel pressure received by the side surface of the floating bearing 17a is the same in the rotational direction of the first driven gear 7 in both the parallel connection state and the series connection state, as can be seen by comparing FIG. 3 and FIG. Distribution. Therefore, the magnitude of the floating force Ff received by the floating bearing 17a does not change even when the connection state of the first gear pump 11 and the second gear pump 13 is switched between parallel and series.

  Therefore, as shown in FIG. 6, the floating bearing 17a of the first driven gear 7 has a high pressure receiving surface 17c and a low pressure receiving surface 17d (in the claims) by a step portion provided on the opposite side to the bearing side of the rotating shaft 7b. Equivalent to the pressure receiving surface). The high pressure receiving surface 17c is arranged on the radially outer side of the rotating shaft 7b, and the low pressure receiving surface 17d is arranged on the radially inner side.

  Then, the fuel pressure after pressure increase by the triple gear pump 1 (fuel pressure at the second discharge port 13b of the second gear pump 13) is introduced into the space where the high pressure receiving surface 17c of the floating bearing 17a exists. In addition, the fuel pressure before pressure increase by the triple gear pump 1 (fuel pressure at the first suction port 11a of the first gear pump 11) is introduced into the space where the low pressure receiving surface 17d exists.

  The space where the high pressure receiving surface 17c exists and the space where the low pressure receiving surface 17d exists are blocked by a seal member. For this reason, the floating bearing 17a includes the first fuel pressure after the pressure increase by the triple gear pump 1 received by the high pressure pressure receiving surface 17c and the fuel pressure before the pressure increase by the triple gear pump 1 received by the low pressure pressure receiving surface 17d. A pressing force Fp in a direction to press the driven gear 7 toward the fixed bearing 17b is generated.

  Here, the fuel pressure before and after the pressure increase by the triple gear pump 1 introduced into the high pressure receiving surface 17c and the low pressure receiving surface 17d, respectively, is either in parallel or in series when the first gear pump 11 and the second gear pump 13 are connected. The same is true. Therefore, the magnitude of the pressing force Fp generated in the floating bearing 17a does not change even when the connection state between the first gear pump 11 and the second gear pump 13 is switched between parallel and series.

  Therefore, in the floating bearing 17a, the high pressure receiving surface is taken into consideration the fuel pressure before and after boosting by the triple gear pump 1 so that the pressing force Fp generated in the floating bearing 17a slightly exceeds the floating force Ff of the floating bearing 17a. The area ratio between 17c and the low pressure receiving surface 17d is set.

  Next, the distribution of the fuel pressure received by the side surface of the floating bearing 19a in the rotation direction of the second driven gear 9 is different between the parallel connection state and the series connection state, as can be seen by comparing FIG. 3 and FIG.

  That is, in the parallel connection state of FIG. 3, the fuel pressure in the second supply path 23 b becomes a low pressure before being boosted by the first gear pump 11. For this reason, the fuel pressure received by the side surface of the floating bearing 19a is a low-pressure region of the approximately 90 ° phase portion in the vicinity of the second suction port 13a, and the remaining approximately 270 ° phase portion connected to the second discharge port 13b is the first. The pressure increase portion from the low pressure to the high pressure by the two-gear pump 13 and the same high pressure region as the fuel after the pressure increase.

  On the other hand, in the serial connection state of FIG. 5, the fuel pressure in the second supply path 23b becomes a high pressure after being boosted by the first gear pump 11, and the fuel pressure of either the second suction port 13a or the second discharge port 13b. Also becomes high pressure. For this reason, the fuel pressure received by the side surface of the floating bearing 19a becomes a high pressure region over the entire circumference of 360 °.

  As described above, the distribution of the fuel pressure received by the side surface of the floating bearing 19a in the rotational direction of the second driven gear 9 is different between the parallel connection state and the series connection state. Therefore, the magnitude of the floating force Ff received by the floating bearing 19a changes when the connection state between the first gear pump 11 and the second gear pump 13 is switched between parallel and series.

  Therefore, the floating bearing 19a of the second driven gear 9 which is substantially omitted below the floating bearing 15a in FIG. 6 is also similar to the floating bearing 17a of the first driven gear 7 on the bearing side of the rotary shaft 9b. A high-pressure receiving surface 19c and a low-pressure receiving surface 19d (corresponding to the pressure receiving surface in the claims, see FIGS. 9 and 10) are formed by the stepped portion provided on the opposite side. The high pressure receiving surface 19c is disposed on the radially outer side of the rotating shaft 9b, and the low pressure receiving surface 19d is disposed on the radially inner side.

  The fuel pressure after the pressure is increased by the triple gear pump 1 (fuel pressure at the second discharge port 13b of the second gear pump 13) is introduced into the space where the high pressure receiving surface 19c of the floating bearing 19a exists. Further, in the space where the low pressure pressure receiving surface 19d exists, the fuel pressure (the second gear pump 13 second state) is changed by switching the operation state of the triple gear pump 1 (the connection state between the first gear pump 11 and the second gear pump 13). The fuel pressure at the suction port 13a) is introduced.

  The space where the high pressure receiving surface 19c exists and the space where the low pressure receiving surface 19d exists are blocked by a seal member. For this reason, the floating bearing 19a has a total of the fuel pressure increased by the triple gear pump 1 received by the high pressure receiving surface 19c and the fuel pressure changed by the switching of the operation state of the triple gear pump 1 received by the low pressure receiving surface 19d. Thus, a pressing force Fp in a direction to press the second driven gear 9 against the fixed bearing 19b side is generated.

  Here, the fuel pressure introduced into the high-pressure receiving surface 19c is the same regardless of whether the first gear pump 11 and the second gear pump 13 are connected in parallel or in series. On the other hand, the fuel pressure introduced into the low pressure receiving surface 19d changes when the connection state between the first gear pump 11 and the second gear pump 13 is switched between parallel and series. For this reason, when the connection state of the 1st gear pump 11 and the 2nd gear pump 13 switches, the magnitude | size of the pressing force Fp of the floating bearing 19a will change. Note that when the first gear pump 11 and the second gear pump 13 are connected in series, the pressing force Fp of the floating bearing 19a cancels out the floating force Ff of the floating bearing 19a.

  Therefore, in the floating bearing 19a, in an operation state in which the first gear pump 11 and the second gear pump 13 are connected in parallel, the pressing force Fp generated in the floating bearing 19a is slightly higher than the floating force Ff of the floating bearing 19a. In consideration of the fuel pressure before and after boosting by the triple gear pump 1, the area ratio between the high pressure receiving surface 19c and the low pressure receiving surface 19d is set.

  Next, the pressure receiving surface of the floating bearing 15a corresponding to the drive gear 5 will be described. The distribution of the fuel pressure received by the side surface of the floating bearing 15a in the rotational direction of the drive gear 5 is different between the parallel connection state and the series connection state as in the second driven gear 9, as can be seen from a comparison between FIG. 3 and FIG.

  That is, in the parallel connection state of FIG. 3, the fuel pressure in the second supply path 23 b becomes a low pressure before being boosted by the first gear pump 11. Therefore, as shown in the explanatory diagram of FIG. 7A and the graph of FIG. 7B, the fuel pressure received by the side surface of the floating bearing 15a is approximately in the vicinity of the first and second suction ports 11a and 13a. The phase portions of 90 ° each become a low pressure region, and alternately, the phase portions of about 90 ° in the vicinity of the first and second discharge ports 11b and 13b are formed by the first gear pump 11 and the second gear pump 13. The pressure increase portion from low pressure to high pressure and the same high pressure region as the fuel after pressure increase.

  The value obtained by integrating the pressure distribution shown in FIG. 7B is the floating force Ff received by the floating bearing 15a in the parallel connection state of the first gear pump 11 and the second gear pump 13.

  On the other hand, in the serial connection state of FIG. 5, the fuel pressure in the second supply path 23 b becomes a high pressure after being boosted by the first gear pump 11. Therefore, as shown in the explanatory diagram of FIG. 8A and the graph of FIG. 8B, the fuel pressure received by the side surface of the floating bearing 15a is low at the phase portion of approximately 90 ° near the first suction port 11a. The phase portion of approximately 270 ° remaining in the vicinity of the second suction port 13a and the first and second discharge ports 11b, 13b is a boosted portion from low pressure to high pressure by the first gear pump 11 and the second gear pump 13. And it becomes the same high pressure area as the fuel after pressure increase.

  A value obtained by integrating the pressure distribution shown in FIG. 8B is the floating force Ff received by the floating bearing 15a in the serial connection state of the first gear pump 11 and the second gear pump 13.

  As described above, the distribution of the fuel pressure received by the side surface of the floating bearing 15a in the rotational direction of the drive gear 5 differs between the parallel connection state and the series connection state. Moreover, the distribution of the fuel pressure received by the side surface of the floating bearing 15a is halved in the high pressure region and the low pressure region in the parallel connection state, whereas in the series connection state, the high pressure region is dominant. Therefore, the magnitude of the floating force Ff received by the floating bearing 15a changes when the connection state between the first gear pump 11 and the second gear pump 13 is switched between parallel and series.

  Therefore, as shown in FIG. 6, the floating bearing 15a of the drive gear 5 has a high step pressure receiving surface 15c and a low pressure receiving surface 15d by means of a double stepped portion provided on the opposite side to the bearing side of the rotating shaft 5b. And a switching pressure receiving surface 15e (corresponding to an additional pressure receiving surface in claims). The high pressure receiving surface 15c is disposed radially outside the rotary shaft 5b, the low pressure receiving surface 15d is disposed radially inside, and the switching pressure receiving surface 15e is disposed between the high pressure receiving surface 15c and the low pressure receiving surface 15d.

  And the fuel pressure after pressure increase by the triple gear pump 1 (fuel pressure at the second discharge port 13b of the second gear pump 13) is introduced into the space where the high pressure receiving surface 15c exists. Further, the fuel pressure before pressure increase by the triple gear pump 1 (fuel pressure at the first suction port 11a of the first gear pump 11) is introduced into the space where the low pressure receiving surface 15d exists. Further, in the space where the switching pressure receiving surface 15e exists, the fuel pressure (the second gear pump 13 of the second gear pump 13) is changed by switching the operation state of the triple gear pump 1 (the connection state of the first gear pump 11 and the second gear pump 13). 2 fuel pressure at the suction port 13a).

  The space in which the high pressure receiving surface 15c exists, the space in which the low pressure receiving surface 15d exists, and the space in which the switching pressure receiving surface 15e exists are blocked by a seal member. For this reason, the floating bearing 15a has a fuel pressure after being boosted by the triple gear pump 1 received by the high pressure receiving surface 15c, a fuel pressure before the boost by the triple gear pump 1 received by the low pressure receiving surface 15d, and a switching pressure receiving surface 15e. The total of the fuel pressure that changes due to the switching of the operating state of the triple gear pump 1 is generated, and a pressing force Fp in the direction of pressing the drive gear 5 against the fixed bearing 15b side is generated.

  Here, the fuel pressure introduced into the high pressure receiving surface 15c and the low pressure receiving surface 15d is the same regardless of whether the first gear pump 11 and the second gear pump 13 are connected in parallel or in series.

  On the other hand, the fuel pressure of the second suction port 13a of the second gear pump 13 received by the switching pressure receiving surface 15e is, as shown in the explanatory view of FIG. 9, in the parallel connection state of the first gear pump 11 and the second gear pump 13, as shown in FIG. Similar to the low pressure receiving surface 15d, the fuel pressure before the pressure is increased by the triple gear pump 1 is obtained. Further, in the serial connection state, as shown in the explanatory diagram of FIG. 10, the fuel pressure after being boosted by the triple gear pump 1 is the same as the high pressure receiving surface 15 c.

  Therefore, the magnitude of the pressing force Fp generated in the floating bearing 15a changes when the connection state between the first gear pump 11 and the second gear pump 13 is switched between parallel and series.

  Therefore, in the floating bearing 15a, the pressing force Fp generated in the floating bearing 15a is such that the first gear pump 11 and the second gear pump 13 are in either a parallel connection state or a serial connection state, or the connection state is Even during switching, the high pressure pressure receiving surface 15c, the low pressure pressure receiving surface 15d, and the switching pressure pressure receiving surface 15e are considered in consideration of the fuel pressure before and after the pressure increase by the triple gear pump 1 so as to slightly exceed the floating force Ff of the floating bearing 15a. The area ratio is set.

  In the floating bearing 15a configured as described above, when the first gear pump 11 and the second gear pump 13 are connected in parallel, the low pressure receiving surface 15d and the switching pressure receiving surface 15e have the fuel pressure before the pressure increase by the triple gear pump 1. Only the high pressure receiving surface 15c becomes the pressure receiving surface and the pressure receiving surface of the fuel pressure after the pressure is increased by the triple gear pump 1.

  Further, in the serial connection state of the first gear pump 11 and the second gear pump 13, only the low pressure pressure receiving surface 15d serves as a pressure receiving surface for the fuel pressure before pressure increase by the triple gear pump 1, and the high pressure receiving surface 15c and the switching pressure receiving surface 15e. The pressure receiving surface of the fuel pressure after the pressure is increased by the triple gear pump 1.

  For this reason, the ratio of the area of the low pressure receiving surface and the high pressure receiving surface is changed between the parallel connection state and the serial connection state of the first gear pump 11 and the second gear pump 13, and the floating force Ff of the floating bearing 15a is changed to the first. Even if the first gear pump 11 and the second gear pump 13 are changed by switching between parallel connection and series connection, the pressing force Fp in the reverse direction can be generated in the floating bearing 15a with an appropriate magnitude.

  When the connection state of the first gear pump 11 and the second gear pump 13 is switched between parallel and series, the fuel pressure at the second suction port 13a of the second gear pump 13 is changed to the first suction of the first gear pump 11. It changes transiently between the fuel pressure (low pressure) at the port 11a and the fuel pressure (high pressure) at the first discharge port 11b. In accordance with this, the floating force Ff of the floating bearing 15a also changes transiently.

  Therefore, when the connection state of the first gear pump 11 and the second gear pump 13 is switched between parallel and series, it is guided to the switching pressure receiving surface 15e of the floating bearing 15a of the drive gear 5 during the transition period from the start to the end. The applied fuel pressure may be changed continuously or stepwise between the fuel pressure before the pressure increase by the triple gear pump 1 (low pressure) and the fuel pressure after the pressure increase (high pressure).

  Note that the change in the fuel pressure guided to the switching pressure receiving surface 15e is preferably matched to the change in the floating force Ff of the floating bearing 15a accompanying the switching of the connection state between the first gear pump 11 and the second gear pump 13.

  Further, the change in the fuel pressure guided to the switching pressure receiving surface 15e is divided into a plurality of pressure receiving surface portions (not shown) in which the switching pressure receiving surface 15e is cut off from each other according to the number of steps of the guided fuel pressure. In addition, a plurality of sets (not shown) of a fuel pressure introduction path and a plurality of nozzle-flapper mechanisms connected to each pressure receiving surface portion can be provided in parallel.

  In this case, the nozzles of the corresponding fuel pressure introduction passages are opened or closed in stages at different fuel pressures by the flappers of each set of nozzle-flapper mechanisms, and floating bearings are provided via the nozzle-flapper mechanisms. The pressure receiving surface portion to which the fuel pressure of 15a is introduced is increased or decreased step by step in accordance with the increase or decrease of the fuel pressure accompanying the switching of the connection state between the first gear pump 11 and the second gear pump 13.

  However, in this case, it is necessary to increase the number of steps of the stepped portion provided in the portion of the floating bearing 15a facing the housing 3, and therefore the number of steps of the stepped portion that can be increased is limited due to the diameter size of the floating bearing 15a. Therefore, the fuel pressure itself guided to the switching pressure receiving surface 15e is increased or decreased continuously or stepwise in accordance with the increase or decrease of the fuel pressure accompanying the switching of the connection state of the first gear pump 11 and the second gear pump 13. More realistic.

  The fuel supply apparatus 20A according to another embodiment of the present invention shown in FIGS. 11 and 12 is configured as described above. In FIG. 11 and FIG. 12, the same reference numerals as those of the fuel supply device 20 in FIG. 3 and FIG. The description of the same configuration as that of the fuel supply device 20 in FIGS. 3 and 5 is omitted.

  The first discharge path 25a connected to the first discharge port 11b of the first gear pump 11 is connected to the space where the switching pressure receiving surface 15e of the floating bearing 15a of the drive gear 5 exists by the pressure introduction path 43a. A nozzle 43b is formed in the middle of the pressure introduction passage 43a, and an orifice 43c is provided at a location closer to the first discharge passage 25a than the nozzle 43b of the pressure introduction passage 43a. The nozzle 43b of the pressure introduction passage 43a extends into the pressure equalizing chamber 45 connected to the pressure introduction passage 43a.

  The pressure equalizing chamber 45 is connected to the first supply path 23a via the communication passage 45a, and the low-pressure fuel (fluid) boosted by the boost pump 21 is transmitted via the first supply path 23a and the communication passage 45a. Supplied. In the present embodiment, the pressure equalizing chamber 45 and the communication passage 45a correspond to the pressure equalizing passage in the claims.

  The pressure equalizing chamber 45 is provided with a nozzle-flapper mechanism 47 that opens and closes the nozzle 43b. Similar to the nozzle-flapper mechanism 31 shown in FIG. 4, the nozzle-flapper mechanism 47 is configured to displace the flapper 51 by a torque motor 49 and open / close the nozzle 43b.

  As shown in FIG. 11, when the flapper 35 closes the nozzle 27e in the low-pressure chamber 29 by the drive control of the torque motor 33 of the nozzle-flapper mechanism 31, the first gear pump 11 and the second gear pump 13 are connected in parallel. The flapper 51 opens the nozzle 43b in the pressure equalizing chamber 45 by the drive control of the torque motor 49 of the nozzle-flapper mechanism 47 according to this.

  When the flapper 51 opens the nozzle 43b, the portion between the nozzle 43b and the orifice 43c in the pressure introduction passage 43a and the portion closer to the switching pressure receiving surface 15e than those portions have the same fuel pressure (in the pressure equalizing chamber 45). Pressure equalization). Therefore, the low pressure fuel pressure is introduced into the switching pressure receiving surface 15e of the floating bearing 15a, as with the low pressure receiving surface 15d.

  When the flapper 51 opens the nozzle 43b, the portion of the pressure introduction passage 43a closer to the first discharge path 25a than the orifice 43c has the same fuel pressure (low pressure) as that in the pressure equalizing chamber 45 due to the presence of the orifice 43c. The pressure is not equalized. The portion of the pressure introduction passage 43a closer to the first discharge path 25a than the orifice 43c is maintained at the same fuel pressure (high pressure) after the pressure increase by the first gear pump 11 as in the first discharge path 25a.

  On the other hand, as shown in FIG. 12, the flapper 35 opens the nozzle 27e in the low pressure chamber 29 by the drive control of the torque motor 33 of the nozzle-flapper mechanism 31, and the first gear pump 11 and the second gear pump 13 are connected in series. Then, the flapper 51 closes the nozzle 43b in the pressure equalizing chamber 45 by the drive control of the torque motor 49 of the nozzle-flapper mechanism 47 according to this.

  When the flapper 51 closes the nozzle 43b, the pressure introduction passage 43a has the same fuel pressure (high pressure) after being boosted by the first gear pump 11 as in the first discharge passage 25a. Therefore, a high fuel pressure is introduced into the switching pressure receiving surface 15e of the floating bearing 15a in the same manner as the high pressure receiving surface 15c.

  When the connection state between the first gear pump 11 and the second gear pump 13 is switched by opening / closing of the nozzle 27e by the flapper 35 and opening / closing of the differential pressure type on / off valve 27 accompanying this, the fuel pressure in the second supply path 23b is switched. Changes between low and high pressure over a period of time. Due to this change, the magnitude of the floating force Ff generated in the floating bearing 15a also changes.

  Here, the period from the start to the end of the change of the fuel pressure in the second supply path 23b can be considered as a transient period in which the connection state between the first gear pump 11 and the second gear pump 13 is switched. In this transition period, it is necessary to increase or decrease the pressing force Fp of the floating bearing 15a in accordance with the increase or decrease of the magnitude of the floating force Ff generated in the floating bearing 15a.

  Therefore, the torque motor of the nozzle-flapper mechanism 47 is synchronized with the drive control of the torque motor 33 of the nozzle-flapper mechanism 31 so that the opening degree of the nozzle 43b by the flapper 51 continuously changes during the transition period described above. 49 is driven and controlled.

  The present invention is not limited to aircraft fuel supply devices, and can be widely applied to fuel supply devices that are used by switching the connection state of the triple gear pump between parallel and series. The present invention is also applicable to a triple gear pump used in devices other than the fuel supply device.

DESCRIPTION OF SYMBOLS 1 Gear pump 3 Housing 5 Drive gear 5a, 7a, 9a Teeth 5b, 5c, 7b, 7c, 9b, 9c, 33c Rotating shaft 7 1st driven gear 9 2nd driven gear 11 1st gear pump 11a 1st inlet 11b 1st Discharge port 13 Second gear pump 13a Second suction port 13b Second discharge port 15a, 17a, 19a Floating bearing 15b, 17b, 19b Fixed bearing 15c, 17c, 19c High pressure receiving surface 15d, 17d, 19d Low pressure receiving surface 15e Switching pressure receiving pressure Surface 20, 20A Fuel supply device 21 Boost pump 23a First supply path 23b Second supply path 23c Check valve 25a First discharge path 25b Second discharge path 27 Differential pressure type on-off valve 27a Valve element 27b Spring chamber 27c Spring 27d Pressure equalization Passage 27e, 43b Nozzle 27f, 43c Orifice 29 Low pressure chamber 31, 47 Nozzle-Flapper mechanism 33, 49 Torque motor 33a, 33b Permanent magnet 33d Armature 33e, 33f Coil 35, 51 Flapper 37 First current driver 39 Second current driver 41 Motor control unit 43 Relief valve 43a Pressure introduction passage 45 Pressure equalizing chamber 45a Communication passage Ff Floating force Fp Pushing force

Claims (3)

A triple gear pump having a first gear pump and a second gear pump capable of switching connection states in parallel and in series,
One drive gear common to the first gear pump and the second gear pump;
Two driven gears respectively corresponding to the first gear pump and the second gear pump and individually meshed with the drive gear;
Each of the gears is supported by bearing one end of the rotation shaft of each of the drive gear and each driven gear, and receiving the pressure before and after the pressure increase by the first gear pump and the second gear pump at the respective pressure receiving surfaces. Floating bearings that are respectively pressed to the side and are movable in the direction of the central axis of each rotary shaft;
A fixed bearing that is non-movable in the direction of the central axis of each rotary shaft, bearing the other end of the rotary shaft of each of the drive gear and each driven gear;
The floating bearing of the drive gear is provided with an additional pressure receiving surface,
The additional pressure receiving surface is provided by the first gear pump or the second gear pump in a state in which the first gear pump and the second gear pump are connected in parallel by the first gear pump and the second gear pump, respectively. In the serial connection state of the first gear pump and the second gear pump, the fluid pressure before the pressure increase is applied and the fluid pressure increased by the first gear pump passes through the second gear pump with the same pressure. The fluid pressure after pressurization is applied,
A triple gear pump characterized by that. A device for supplying fluid pressurized by a gear pump to the outside,
A triple gear pump according to claim 1;
A switching unit that switches a connection state between the first gear pump and the second gear pump of the triple gear pump between a parallel connection state and a series connection state;
A fluid supply device comprising:   A pressure introducing passage for connecting an outlet of the first gear pump or the second gear pump to an additional pressure receiving surface provided in a floating bearing of a driving gear of the triple gear pump; and the pressure introducing passage is connected to an inlet of the first gear pump. A pressure equalizing passage and an opening / closing valve that opens and closes a connection point of the pressure equalizing passage to the pressure introduction passage, and during the transition period from the start to the end of the connection state switching by the switching portion, 3. The fluid supply device according to claim 2, wherein the valve opening is changed continuously or stepwise between fully closed and fully opened.

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