JP4111141B2 - Multistage pump system - Google Patents

Description

  The present invention relates to a multi-stage pump system configured to supply a high pressure generated by a booster using a discharge pressure of a low-pressure pump to a discharge side of a high-pressure pump.

Conventionally, as such a multistage pump system, there exists a thing as shown, for example in patent document 1. FIG. That is, in the pressure path for supplying high-pressure fuel from the fuel tank to the injector, a low-pressure pump is arranged in series upstream and a high-pressure pump is arranged in series downstream. This pressure path is provided with a booster that supplies high pressure to the discharge side of the high-pressure pump by displacement of the movable partition using the discharge pressure of the low-pressure pump. By this high pressure supply, it is possible to improve the rate of increase of the injector injection pressure when the discharge pressure of the high pressure pump is insufficient, such as when the system is started.
JP-A-5-321787

  However, in such a multi-stage pump system, although the increase rate of the injector injection pressure described above is expected, the injection amount may vary due to pressure pulsation generated on the high pressure pump discharge side of the pressure path during steady operation, such as after the pressure increase. There was room for improvement in this regard.

  The present invention has been made in view of such circumstances, and the purpose thereof is to improve the pressure rise rate on the discharge side of the high-pressure pump at the start, and the pressure generated on the discharge side of the high-pressure pump during steady operation. An object of the present invention is to provide a multistage pump system capable of suppressing pulsation.

In the following, means for achieving the above object and its effects are described.
First, the invention according to claim 1 incorporates a plurality of pumps arranged in series in a pressure path from the suction side to the discharge side, and a movable partition wall capable of receiving the discharge pressure of the low-pressure side pump among the pumps. And a booster capable of generating a boost pressure higher than the discharge pressure by supplying the discharge pressure to the discharge side of the high-pressure pump in the pressure path. A control valve whose opening degree is controlled so as to change the passage cross-sectional area of the pressure path, and a pressing force acting on the movable partition wall based on the pressure on the discharge side of the high-pressure pump. By changing the balance with the pressing force acting on the movable partition based on the discharge pressure of the low-pressure side pump based on the opening control of the control valve, the function of the booster is A boost function that introduces boost pressure to the discharge side of the high-pressure pump, and a pressure fluctuation suppression function that suppresses the pressure fluctuation by displacing the movable partition wall in accordance with pressure fluctuation on the discharge side of the high-pressure pump. The gist of this is to switch the mode.

  In this invention, the booster has both a boost function for introducing high pressure (boost pressure introduction) to the discharge side of the high pressure pump and a pressure fluctuation suppressing function for suppressing pressure fluctuation on the discharge side of the high pressure pump. Both of these functions can be switched through opening control of the control valve. That is, according to the present invention, both functions of the booster described above can be properly used according to the pressure state of the pressure path, for example, and as a result, while improving the pressure rise rate on the discharge side of the high-pressure pump in the pressure path, The pressure pulsation and the like on the same discharge side during steady operation can be suitably suppressed.

  Further, as a specific aspect of changing the balance of the pressing force in this way, according to the invention of claim 1, in the invention of claim 1, the balance change of the pressing force is A configuration in which the ratio between the two pressures acting on the movable partition wall is changed based on the opening degree control can be adopted.

  Further, according to the invention described in claim 3, in the invention described in claim 1 or 2, the change in the balance of the pressing force is such that the ratio of the action area of each pressure to the movable partition wall is controlled by the opening degree control. It is possible to adopt a configuration in which the change is made based on the change.

  And, as a specific mode when changing the ratio of the acting area of each pressure in this way, according to the invention of claim 4, in the invention of claim 3, the movable partition wall is A high pressure side pressure receiving surface constituting the inner wall surface of the pressure chamber into which the pressure on the discharge side of the high pressure side pump is introduced, and a low pressure side pressure receiving surface constituting the inner wall surface of the pressure chamber into which the discharge pressure of the low pressure side pump is introduced. And at least one of the two pressure chambers is partitioned into a plurality of compartments whose inner walls are the pressure-receiving surfaces corresponding to the pressure chambers, and the ratio of the working area is changed by introducing the pressure in the pressure chambers. It is possible to adopt a configuration in which the number of the compartments to be changed is changed based on the opening degree control.

  As an aspect of the control valve for performing such opening degree control, as in the invention according to claim 5, in the invention according to any one of claims 1 to 4, the control valve is provided for the high-pressure side pump. It is possible to adopt a configuration in which the valve is a variable control valve whose opening can be changed by a command signal from the outside based on the pressure on the discharge side.

  Further, according to the invention described in claim 6, in the invention described in any one of claims 1 to 5, the control valve is mechanically and autonomously according to the pressure on the discharge side of the high-pressure pump. It is possible to adopt a configuration in which the autonomous control valve is capable of changing the opening degree automatically.

  According to the fifth and sixth aspects of the present invention, the above-described functions of the booster and switching of these functions can be made suitable in accordance with the pressure on the discharge side of the high-pressure pump. Furthermore, in the invention described in claim 6, a sensor is used to detect the pressure on the discharge side of the high-pressure pump, or a control device such as a CPU that performs calculation based on the detection result of the sensor is used. In comparison with the embodiment in which the control valve opening degree is controlled in a different manner, it is not necessary to provide such a sensor and a control device, so that the configuration is simplified.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the movable partition receives the pressure on the discharge side of the high pressure pump and the low pressure pump. A relief passage that communicates with the low pressure side pressure receiving surface that receives the discharge pressure and a valve body that can open and close the passage, and increase the pressure on the discharge side of the high pressure pump through the pressure relief through the relief passage. The gist is that a high-pressure relief valve mechanism that can be suppressed is further provided.

  According to this invention, in addition to the pressure fluctuation suppressing function of the booster described above, a further effect of suppressing the pressure rise can be obtained. In addition, for example, a passage is provided in the housing that houses the movable partition wall in the booster, and the pressure on the discharge side of the high-pressure pump is introduced to the low-pressure pump side through the passage, thereby suppressing the pressure increase on the discharge side of the high-pressure pump. The housing can be easily downsized as compared with the configuration configured as described above.

The gist of the invention according to claim 8 is that, in the invention according to any one of claims 1 to 7, a rotary pump is used.
According to the present invention, for example, the pressure pulsation can be reduced as compared with an aspect in which a reciprocating pump is used.

  Further, as a specific aspect of the above-described invention, as in the invention described in claim 9, in the invention described in any one of claims 1 to 8, the discharge port of the pressure path is for supplying fuel. It is possible to adopt a configuration in which the injectors are connected. That is, the multistage pump system of the present invention is used for fuel supply.

(First embodiment)
Hereinafter, an embodiment in which the present invention is embodied as a multistage pump system used for fuel supply of an on-vehicle internal combustion engine will be described with reference to FIGS.

  As shown in FIG. 1, the multistage pump system includes a fuel supply path 13 for supplying fuel from a suction-side fuel tank 11 toward a discharge-side injector 12. In the middle of the fuel supply path 13, a low-pressure pump 14 and a high-pressure pump 15 are arranged in series, that is, in multiple stages. Both pumps 14 and 15 are operatively connected to an internal combustion engine 17 which is a drive source and a fuel supply destination via a common rotating shaft 16. In the present embodiment, rotary pumps are used for these pumps 14 and 15. Both pumps 14 and 15 are driven by the driving force from the internal combustion engine 17 so that the fuel in the fuel tank 11 is pumped to the high-pressure side pump 15 via the low-pressure side pump 14, and the same pressure-fed fuel is fed to the high-pressure side. The pressure is further increased through the pump 15 and sent to the injector 12 side.

  A pressure regulator 18 is disposed between the low pressure side pump 14 and the high pressure side pump 15 in the fuel supply path 13. The pressure regulator 18 supplies the fuel in the fuel supply path 13 via the return path 19 when the fuel pressure in the portion between the low pressure pump 14 and the high pressure pump 15 in the fuel supply path 13 becomes equal to or higher than a predetermined pressure. By returning to the fuel tank 11, the fuel pressure of the said part in the fuel supply path 13 is hold | maintained less than predetermined pressure.

  In the fuel supply path 13, a high-pressure reservoir 21 is disposed between the discharge port 20 to which the injector 12 is connected and the high-pressure pump 15. The fuel discharged from the high-pressure pump 15 is temporarily stored in the high-pressure reservoir 21 and then injected from the injector 12. A control valve 30 </ b> C that can open and close the portion of the fuel supply path 13 between the high-pressure pump 15 and the high-pressure reservoir 21 is provided.

  In such a multi-stage pump system, the discharge pressure of the low-pressure side pump 14 is raised to a desired pressure relatively early immediately after starting, but the discharge pressure of the high-pressure side pump 15 is set to a pressure higher than the above pressure. Sometimes it takes a relatively long time to reach that goal.

  In the present embodiment, in order to eliminate such inconvenience, a booster 40 that can supply boost pressure higher than the same pressure to the high-pressure reservoir 21 by using the pressure of the fuel discharged from the low-pressure side pump 14 is provided. . The booster 40 is provided in the middle of a booster path 41 that connects the portion between the pressure regulator 18 and the high-pressure pump 15 in the fuel supply path 13 and the high-pressure reservoir 21. Of the booster path 41, the first booster path 41 a that connects the booster 40 and the portion between the pressure regulator 18 and the high-pressure pump 15 in the fuel supply path 13 described above is discharged fuel of the low-pressure pump 14 (that is, The pressure of the discharged fuel) can be introduced into the booster 40. In addition, the second booster path 41 b that connects the booster 40 and the high-pressure reservoir 21 in the booster path 41 can introduce the discharged fuel (that is, the pressure of the discharged fuel) boosted by the booster 40 into the high-pressure reservoir 21. To do.

  The first booster path 41a is provided with a control valve 30A capable of opening and closing the path 41a. A portion between the control valve 30 </ b> A and the booster 40 in the path 41 a is connected to the return path 19 via a pressure adjustment path 42. The pressure adjustment path 42 is provided with a control valve 30D that can open and close the path 42. The second booster path 41b is provided with a control valve 30B that can open and close the path 41b. The booster 40 and the return path 19 are connected via a drain path 43, and the drain discharge from the booster 40 to the return path 19 is performed via the drain path 43.

  In the present embodiment, the fuel supply path 13, the booster path 41, the pressure adjustment path 42, the drain path 43, and the return path 19 described above constitute a pressure path from the suction side to the discharge side.

  Each of the control valves 30A to 30D is an electromagnetic valve whose opening degree is controlled through other energization control based on a command signal from an ECU (electronic control unit) 31, and each is provided based on this opening degree control. The pressure path (fuel supply path 13, booster path 41, pressure adjustment path 42) is opened and closed (that is, the passage cross-sectional area is changed).

  The ECU 31 performs opening control of these control valves 30A to 30D based on the operating state of the internal combustion engine 17 and the like. The ECU 31 receives detection results of an oxygen sensor 32, a crank angle sensor 33, and an ignition switch 34 that detect the oxygen concentration in the exhaust gas of the internal combustion engine 17. The ECU 31 captures these detection results and detects the oxygen concentration in the exhaust, the engine speed, and the ignition on / off status.

  The ECU 31 takes in the detection results of a plurality of pressure sensors 35 disposed at various locations in the pressure path, and detects the pressure at each location. Among the plurality of pressure sensors 35, the pressure sensors 35a and 35b detect the pressure at the suction side of the low-pressure side pump 14 and the portion between the pump 14 and the pressure regulator 18 in the same order in the fuel supply path 13. The pressure sensors 35c, 35d, and 35g are also arranged in the same order in the fuel supply path 13 between the pressure regulator 18 and the high-pressure pump 15, between the pump 15 and the control valve 30C, the high-pressure reservoir 21 and the discharge port 20. The pressure in the part between is detected. Further, the pressure sensor 35e detects the pressure between the control valve 30A and the booster 40 in the first booster path 41a, and the pressure sensor 35f detects the pressure at the part between the booster 40 and the control valve 30B in the second booster path 41b. To do.

  As shown in FIG. 2, a pressure chamber 52 into which fuel is introduced is formed in the housing 51 of the booster 40, and a movable partition wall 53 is accommodated in the pressure chamber 52 so as to be slidable, that is, displaceable. By accommodating the movable partition wall 53, the pressure chamber 52 is divided into compartments 52a, 52b, and 52c that are pressure-isolated from each other. The first booster path 41a described above is connected to the compartment 52a, and the second booster path 41b is connected to the compartment 52c. A drain path 43 is connected to the branch chamber 52b.

  The compartment 52a is exposed to a low pressure side pressure receiving surface 53a of the movable partition wall 53 on which a pressure related to the displacement of the movable partition wall 53 acts. A high pressure side pressure receiving surface 53c of the movable partition wall 53 on which a pressure related to the displacement of the movable partition wall 53 acts is exposed to the compartment 52c. In addition, a drain pressure receiving surface 53b of the movable partition wall 53 on which a pressure related to the displacement of the movable partition wall 53 acts is exposed to the compartment 52b. That is, each of the pressure receiving surfaces 53a, 53b, and 53c constitutes the inner wall surface of the branch chambers 52a, 52b, and 52c in the same order. When the projected areas of the pressure receiving surfaces 53a, 53b, and 53c in the displacement direction are Sa, Sb, and Sc in the same order, these relationships are as shown in the following equation (1).

Sa = Sb + Sc (Formula 1)
Further, in the compartments 52a and 52b, for example, when the same pressure as that in the fuel tank 11 is applied to all the pressure receiving surfaces 53a to 53c, the movable partition wall 53 is located at the position closest to the first booster path 41a in the housing 51 (this embodiment). In the embodiment, holding compression springs 54 and 55 for holding this position in the original position are accommodated. FIG. 2A shows a state in which the movable partition wall 53 is disposed at this original position. A contact restricting member (not shown) for restricting the movement of the movable partition wall 53 toward the first booster path 41a (left side in the drawing) is provided in the housing 51. For example, all the pressure receiving surfaces 53a to 53c described above are provided. When the same pressure as that in the fuel tank 11 is applied, the movable partition wall 53 is brought into contact with the contact restricting member with almost no pressing force.

  For example, from this state, when the movable partition wall 53 is displaced toward the second booster path 41b against the force of the holding compression spring 55 due to the pressure increase of the compartment 52a acting on the low pressure side pressure receiving surface 53a, the area to receive pressure is received. Since Sa is larger than the area Sc, the pressure in the compartment 52c is increased more than the pressure increase in the compartment 52a. That is, at this time, a boost pressure higher than the discharge pressure of the low-pressure pump 14 is generated in the compartment 52c by the displacement of the movable partition wall 53 and supplied to the second booster path 41b. Incidentally, when the movable partition wall 53 is displaced, the fuel in the compartment 52 b is discharged through the drain path 43.

  In the present embodiment, the pressure balance acting on the movable partition wall 53, that is, the ratio between the pressure acting on the low pressure side pressure receiving surface 53a and the pressure acting on the high pressure side pressure receiving surface 53c is controlled by the ECU 31 to control the opening of each control valve 30A-30D. Thus, the balance of the pressing force to the movable partition wall 53 related to the displacement can be changed.

  2 (b) and 2 (c) show a state in which the pressure balance and the pressing force balance based on the pressure balance are biased toward the higher pressure in the compartment 52a compared to the state in FIG. 2 (a). Show. FIG. 2B shows a state in which the movable partition wall 53 is at a position closest to the second booster path 41 b in the housing 51 (this position is referred to as a boost position in the present embodiment).

  FIG. 2C shows a state in which the movable partition wall 53 is in an intermediate position between the original position and the boost position (in this embodiment, this position is called a relief neutral position). The state of being in the relief neutral position is realized when the bias of the pressure balance (and the pressing force balance) is smaller than that in the state in which the movable partition wall 53 is in the boost position. The maintenance of this state can be realized through feedback control of the opening degree of the control valves 30A to 30D that is continuously executed by the ECU 31 based on the detection result of a neutral position sensor (not shown) provided in the booster 40. .

  2A to 2D, the movable partition wall 53 is provided with a relief passage 53d that connects the low pressure side pressure receiving surface 53a and the high pressure side pressure receiving surface 53c. In 53d, a ball valve 53e is disposed as a valve body capable of opening and closing the passage 53d. The ball valve 53e is pressed toward a valve seat formed in the passage 53d by a compression spring 53f disposed in the relief passage 53d. The pressure on the side of the compartment 52c acting on the ball valve 53e is higher than the pressure on the side of the compartment 52a, and the difference between the two pressures is such that the ball valve 53e is separated from the valve seat against the force of the compression spring 53f. When this happens, the pressure (fuel) in the compartment 52c is introduced into the compartment 52a through the relief passage 53d, that is, the pressure is released (the state shown in FIG. 2D). If the pressure balance of both the chambers 52a and 52c in the state of FIG. 2A is biased toward the higher pressure in the compartment 52c, the pressing force of the movable partition 53 against the contact restricting member is increased. Become. The opening of the ball valve 53e (separation from the valve seat) is caused by such a pressure balance becoming larger than a predetermined value.

  The relief passage 53d, the ball valve 53e, and the compression spring 53f are provided on the discharge side of the high-pressure pump 15 through pressure introduction (pressure release) from the high-pressure side pressure receiving surface 53c to the low-pressure side pressure receiving surface 53a via the relief passage 53d. A high-pressure relief valve mechanism that can suppress the pressure rise is configured.

  Next, the pressure control mode of the pressure path based on the opening control of the control valves 30A to 30D by the ECU 31 will be described below using the control matrix M101 shown in FIG. In the figure, “A” to “D” in the “control valve open / close state” column correspond to the control valves 30A to 30D in the same order, and “a” to “g” in the “pressure sensor detection result” column respectively. It corresponds to the pressure sensors 35a to 35g in the same order.

  First, before starting the engine, all the control valves 30A to 30D are deenergized to be "closed (in the present embodiment, fully closed)". In this state, the detection results of all the pressure sensors 35a to 35g are equal to the pressure in the fuel tank 11 (this pressure is referred to as “0” for convenience). At this time, the movable partition wall 53 of the booster 40 is in a state of being disposed at the original position. In the state where the movable partition wall 53 is in this original position, the volume of the compartment 52c is maximized, so that the amount of fuel stored in the compartment 52c is maximized.

  When the ignition switch 34 is turned on from this state, the pumps 14 and 15 are started to be driven with the rotation of the starter motor for starting the engine, and only the control valves 30A and 30B are detected by the ECU 31 based on detecting this on. “Open (full open state in this embodiment)” (1 at start-up). In this state, the detection results of the pressure sensors 35b, 35c, and 35e become equal to the discharge pressure of the low-pressure pump 14 (hereinafter, this pressure is referred to as “low”) as the low-pressure pump 14 starts to be driven. It is assumed that the discharge pressure of the low-pressure side pump 14 is increased to a pressure almost equal to that during steady operation even immediately after the start of such driving.

  That is, when the pressure in the compartment 52a of the booster 40 is increased from “0” to “low”, the movable partition wall 53 is displaced from the original position to the boost position, and is transferred from the compartment 52c to the high-pressure reservoir 21 via the second booster path 41b. High pressure fuel (fuel boosted to the boost pressure) is supplied. This high-pressure fuel is a fuel having a sufficient pressure for suitably starting the engine, and a pressure equivalent to this fuel pressure is hereinafter referred to as “high”. As a result, the detection results of the pressure sensors 35f and 35g become “high”. At this point in time, since the drive has just started, the pressure increase by the high-pressure pump 15 is still nothing, and the detection result of the pressure sensor 35d is only low by the low-pressure pump 14 and indicates “low”. That is, due to the displacement of the movable partition wall 53, the injection pressure of the injector 12 is rapidly increased at a speed exceeding the increase speed of the discharge pressure of the high-pressure pump 15.

  Next, the ECU 31 sets the control valve 30A to “closed” and controls the control valves 30B, 30C, and 30D based on the detection that the pressure sensor 35d has reached a predetermined pressure (“low” in the present embodiment). “Open” (2 at start-up). Therefore, as indicated by the detection result of the pressure sensor 35e, the pressure in the compartment 52a is reduced to “0” by releasing the pressure through the pressure adjustment path 42. As the discharge pressure of the high-pressure pump 15 increases, the detection result of the pressure sensor 35d becomes “high”. Therefore, when the control valve 30C is opened, high-pressure fuel from the high-pressure pump 15 is introduced into the high-pressure reservoir 21 and the compartment 52c. As a result, the pressing force balance acting on the movable partition 53 is reversed and the movable partition 53 is returned from the boost position to the original position.

  Then, the ECU 31 sets the control valves 30A, 30B, and 30D to “closed” based on the fact that the elapsed time since the open / closed state of the control valves 30A to 30D has been set to the above-described “starting time 2” state has reached a predetermined time. At the same time, the control valve 30C is set to “open” (starting 3). As a result, the compartments 52a and 52c of the booster 40 are pressure-isolated from the fuel supply passage 13 and the return passage 19, and the pressure in all the compartments 52a to 52c becomes “0” so that the movable partition wall 53 is held in the original position. Is done. Then, the high-pressure fuel supply to the injector 12 by the high-pressure pump 15 is continued. As described above, the movable partition wall 53 is displaced from the original position to the boost position and then returned to the original position, so that when the engine start cannot be completed, the injection pressure of the injector 12 by the booster 40 again. You will be able to climb.

  Next, when the ECU 31 determines that the internal combustion engine 17 has shifted to a steady operation state because the engine rotational speed based on the detection result of the crank angle sensor 33 has reached a predetermined rotational speed, for example, the control valves 30A, 30B, 30D By adjusting the opening degree, the movable partition wall 53 is displaced from the original position to the relief neutral position and held at the same position. The opening adjustment by the ECU 31 is performed by feedback control while detecting the position of the movable partition wall 53 based on the detection result from the neutral position sensor provided in the booster 40.

  In the present embodiment, the ECU 31 changes the ratio of the pressure acting on the movable partition wall 53 based on the opening control of the control valves 30A to 30D, thereby increasing the function of the booster 40 toward the injector 12 as described above. The function is switched between a function for introducing (boost function) and a function for suppressing pressure fluctuation on the injector 12 side (pressure fluctuation suppressing function).

  That is, during steady engine operation, the ECU 31 holds the movable partition wall 53 in the relief neutral position as described above, and performs the opening control of the control valves 30A to 30D based on the detection result of the pressure sensor 35g. It functions to suitably maintain the injection pressure of the injector 12 through the displacement of the partition wall 53. For example, if the ECU 31 determines that the pressure on the injector 12 side has become higher than the above “high” due to the influence of the pulsation of the discharge pressures of the pumps 14 and 15, the ECU 31 closes the control valve 30A and controls the control valves 30B to 30B. 30D is set to “open” (at the time of steady operation 1). As a result, the pressure in the compartment 52a becomes "0", and the movable partition wall 53 is displaced from the relief neutral position toward the original position due to the fluctuation of the pressure balance accompanying this. Along with this displacement, the pressure increase on the side of the compartment 52c, that is, the injector 12 is suppressed.

  If the pressure increase in the compartment 52c at this time is so large that it cannot be absorbed by the displacement of the movable partition wall 53, the ball valve 53e is opened (separated from the valve seat), and the relief passage 53d is in a communication state. Thus, the pressure in the compartment 52c is introduced into the compartment 52a through the passage 53d, thereby avoiding an excessive pressure increase in the compartment 52c.

  On the other hand, when determining that the pressure on the injector 12 side is lower than the above "high", the ECU 31 sets the control valve 30D to "closed" and sets the control valves 30A to 30C to "open" (during steady operation 2). . As a result, the pressure in the compartment 52a is raised to “low”, and the movable partition wall 53 is displaced from the relief neutral position to the boost position side due to the fluctuation of the pressure balance. With this displacement, the pressure drop on the side of the compartment 52c, that is, the injector 12 is suppressed. By such opening degree control by the ECU 31, pressure pulsation on the injector 12 side is suppressed (pressure fluctuation suppressing function).

  When the ignition switch 34 is turned off, both the pumps 14 and 15 are stopped, and based on the detection of the off, the ECU 31 first sets the control valves 30A and 30D to “closed” and the control valves 30B and 30C. Is “open” (when stopped). Immediately after this, the pressure in the compartment 52 a of the booster 40 becomes “0”, while the pressure in the compartment 52 c remains “high” due to the influence of the residual pressure in the high-pressure reservoir 21. The movable partition wall 53 can be quickly returned to the original position due to such a change in pressure balance.

  When the ECU 31 detects that the detection result of the pressure sensor 35g has become “0”, it is considered that the pressure in the high-pressure reservoir 21 has decreased to a pressure equivalent to that in the fuel tank 11 due to fuel injection from the injector 12. Then, energization of all the control valves 30A to 30D is stopped to be “closed” (2 when stopped). And the pressure of all the compartments 52a-52c of the booster 40 becomes "0", and the movable partition 53 is hold | maintained in an original position.

  If the internal combustion engine 17 stalls during steady operation, the ECU 31 detects the occurrence of the stall based on the detection result of the oxygen sensor 32, and the opening degree is the same as that of the above-mentioned "stop time 1" and "stop time 2". It comes to perform control.

  As described above, with the boost function and the pressure fluctuation suppression function of the booster 40, the relationship between the engine speed and the injection pressure of the injector 12 is as shown in FIG. A diagram 401 shown in the figure represents the above relationship that is optimal for the internal combustion engine 17. A diagram 402 shows a case where the booster 40 is not operated by maintaining the control valves 30A and 30B "closed", and a diagram 403 shows a case where the booster 40 is operated as described above. .

  The peak P appearing in the low rotational speed region in the diagram 401 suggests that an injection pressure equivalent to that in the high rotational speed region is desirable when the internal combustion engine 17 is started. As shown in the diagram 402, when the booster 40 is not functioning, the injection pressure is insufficient in the low rotation speed region, and conversely excessive in the high rotation speed region. Then, as shown in the diagram 403, the booster 40 is functioned so that the injection pressure in the low rotation speed region is raised so as to be close to the diagram 401, and the injection pressure in the high rotation speed region is the same as the line. It is suppressed so as to be close to FIG.

In the present embodiment, the following effects can be obtained.
(1) According to this embodiment, the pressure acting on the high pressure side pressure receiving surface 53c in the movable partition wall 53 of the booster 40 and the pressure acting on the low pressure side pressure receiving surface 53a through the opening degree control of the control valves 30A to 30D. By changing the ratio, the balance of the pressing force acting on the movable partition wall 53 is changed. Based on the change in the pressing force balance, both the boost function and the pressure fluctuation suppression function in the booster 40 can be used properly. Accordingly, by using both these functions properly according to, for example, the pressure state at the discharge port 20 of the fuel supply passage 13, the rate of increase in the fuel injection pressure of the injector 12 is improved, and during steady operation of the internal combustion engine 17. Thus, the pulsation of the fuel injection pressure can be suitably suppressed.

  (2) The booster 40 is provided with a high-pressure relief valve mechanism capable of releasing pressure from the high-pressure compartment 52c to the low-pressure compartment 52a via a relief passage 53d provided in the movable partition wall 53. Therefore, in addition to the pressure fluctuation suppressing function of the booster 40 described above, a further pressure increase suppressing effect can be obtained on the discharge side of the high-pressure pump 15.

  Further, for example, a passage is provided in the housing 51 of the booster 40, and the pressure on the discharge side of the high-pressure pump 15 is introduced to the low-pressure pump 14 side through the passage to increase the pressure on the discharge side of the high-pressure pump 15. The housing 51 can be easily downsized as compared with the configuration in which it is suppressed.

(3) Both pumps 14 and 15 are rotary. Therefore, for example, pressure pulsation can be reduced as compared with a mode in which a reciprocating pump is used.
(Second Embodiment)
Unlike the first embodiment, the second embodiment is not mechanically and autonomously opened according to the pressure condition in the pressure path, but not by a control valve that is otherwise controlled based on a command from the ECU 31. The pressure of the same pressure path is adjusted by a control valve that changes the degree. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals in the drawings, and a duplicate description is omitted.

  As shown in FIG. 5, in the multistage pump system of the present embodiment, the pressure sensors 35a to 35f, the oxygen sensor 32, the crank angle sensor 33, the ignition switch 34, and the ECU 31 provided in various places in the first embodiment. The control valves 30 </ b> A to 30 </ b> D that have been controlled to open and close by are omitted.

  In the present embodiment, the booster 60 is provided in the middle of the booster path 61 that connects the portion between the pressure regulator 18 and the high-pressure pump 15 in the fuel supply path 13 and the high-pressure reservoir 21. Like the booster 40 of the first embodiment, the booster 60 can supply a boost pressure higher than the same pressure to the high-pressure reservoir 21 using the discharge pressure of the low-pressure pump 14.

  Of the booster path 61, the first booster path 61 a that connects the portion between the pressure regulator 18 and the high-pressure pump 15 in the fuel supply path 13 and the booster 60 introduces the discharge pressure of the low-pressure pump 14 to the booster 60. Make it possible. Further, the second booster path 61 b that connects the booster 60 and the high pressure reservoir 21 in the booster path 61 enables the boost pressure boosted by the booster 60 to be introduced into the high pressure reservoir 21.

  The booster 60 is connected to a pressure control path 62 that branches from the middle of the first booster path 61a and allows the discharge pressure of the low-pressure pump 14 to be introduced into the booster 60 in parallel with the branch. . The pressure control path 62 is provided with a control valve 70 that can open and close the path 62.

  The control valve 70 incorporates a pressure sensing mechanism such as a diaphragm, for example, and controls the opening degree mechanically and autonomously according to the pressure applied to the pressure sensing mechanism via the pressure sensing path 63, so-called autonomous control. It is a valve. The pressure detection path 63 is connected to the pressure detection section S between the high pressure pump 15 and the high pressure reservoir 21 in the fuel supply path 13, and the control valve 70 is the pressure of the pressure detection section S, that is, the high pressure side pump 15. The opening degree is controlled according to the pressure on the discharge side. When the pressure of the pressure detection unit S is greater than the pressure equivalent to the discharge pressure of the low-pressure side pump 14 (that is, the pressure equivalent to the above-mentioned “low”), the control valve 70 is fully opened (ie, the above-mentioned). When the pressure is equal to or lower than the pressure, the opening degree is fully closed (that is, the same as the above-mentioned “closed”). The control valve 70 opens and closes the pressure control path 62 based on such opening control.

  The booster 60 is connected to the return path 19 via the drain path 64, and the drain is discharged from the booster 60 to the return path 19 via the drain path 64. In the present embodiment, the fuel supply path 13, booster path 61, pressure control path 62, drain path 64, and return path 19 described above constitute a pressure path from the suction side to the discharge side.

  As shown in FIG. 6, a pressure chamber 82 into which fuel is introduced is formed in the housing 81 of the booster 60, and a movable partition wall 83 is accommodated in the pressure chamber 82 so as to be slidable, that is, displaceable. By accommodating the movable partition wall 83, the pressure chamber 82 is divided into compartments 82a, 82b, 82c, and 82d that are pressure-isolated from each other. The first booster path 61a described above is connected to the compartment 82a, and the second booster path 61b is connected to the compartment 82d. A pressure control path 62 is connected to the compartment 82b, and a drain path 64 is connected to the compartment 82c.

  In both of the compartments 82a and 82b into which the discharge pressure of the low-pressure side pump 14 is introduced, the first low-pressure side pressure receiving surface 83a and the second low-pressure side pressure receiving surface of the movable partition 83 on which the pressure relating to the displacement of the movable partition 83 acts. 83b is exposed. That is, in this embodiment, the low pressure side pressure receiving surface that receives the discharge pressure of the low pressure side pump 14 in the movable partition wall 83 is a part of the inner wall surface of the plurality of pressure chambers (partition chambers 82a and 82b) into which the discharge pressure is introduced. These are constituted by two pressure receiving surfaces 83a and 83b.

  Further, the high pressure side pressure receiving surface 83 d of the movable partition wall 83 on which the pressure related to the displacement of the movable partition wall 83 is exposed is exposed to the compartment 82 d into which the pressure on the discharge side of the high pressure pump 15 is introduced. Further, a drain pressure receiving surface 83c of the movable partition wall 83, to which a pressure related to the displacement of the movable partition wall 83 acts, is exposed to the branch chamber 82c. These pressure receiving surfaces 83c and 83d constitute the inner wall surfaces of the compartments 82c and 82d in the same order. Assuming that the projected areas in the displacement direction of the pressure receiving surfaces 83a, 83b, 83c, and 83d are Aa, Ab, Ac, and Ad in the same order, these relationships are as shown in the following equations 2 and 3.

Aa + Ab = Ac + Ad (Formula 2)
Aa> Ad (Formula 3)
Further, in the compartments 82b and 82c, for example, when the same pressure as that in the fuel tank 11 is applied to all the pressure receiving surfaces 83a to 83d (this pressure is also referred to as “0” in this embodiment), the movable partition wall 83 is displaced. Holding compression springs 84 and 85 are held for holding at an intermediate position in the pressure chamber 82 in the direction (this position is referred to as an original position in this embodiment). FIG. 6A shows a state in which the movable partition wall 83 is disposed at this original position.

  For example, when the low-pressure pump 14 starts to be driven from the state where the same pressure as that in the fuel tank 11 is applied to all of the pressure receiving surfaces 83a to 83d, the compartment 82a that acts on the low-pressure receiving surface 83a accordingly. The pressure increases. Also in this embodiment, the discharge pressure of the low-pressure side pump 14 is set to “low”. When the movable partition wall 83 is displaced toward the second booster path 61b against the force of the holding compression spring 85 by this pressure increase, the pressure of the area 82d is larger than the area Ad, so that the pressure of the compartment 82d is the same as that of the compartment 82a. The pressure is increased more than the pressure increase. That is, at this time, a boost pressure higher than the discharge pressure of the low-pressure side pump 14 (in the present embodiment, this pressure is set to “medium”) is generated in the compartment 82d by the displacement of the movable partition wall 83, and the second booster It will be supplied to the path 61b. The pressure “medium” is lower than the normal injection pressure of the injector 12 during normal engine operation (injection pressure that is not abnormal. In the present embodiment, this pressure is referred to as “high”), but the engine starts well. This is the fuel pressure that can be achieved.

  6B, for example, as described above, the pressing force balance in the displacement direction acting on the movable partition wall 83 based on the pressure in the pressure chamber 82 is compared with the state of FIG. The state where the low pressure side pump 14 side (the 1st booster path | route 61a and the pressure control path | route 62 side) is biased to the side which becomes larger than the high pressure side pump 15 side (the 2nd booster path | route 61b side) is shown. In the drawing, a state is shown in which the movable partition wall 83 is at a position closest to the second booster path 61b in the pressure chamber 82 (this position is referred to as a boost position in the present embodiment).

  Conversely, in FIG. 6C, the above-described pressing force balance is biased toward the side where the high-pressure side pump 15 side is larger than the low-pressure side pump 14 side as compared with the state of FIG. 6A. Indicates the state. In the drawing, a state is shown in which the movable partition wall 83 is at a position closest to the first booster path 61a in the pressure chamber 82 (in this embodiment, this position is referred to as a fail-safe position).

  In the present embodiment, as described above, when the pressure in the compartment 82b is “0” (however, the pressure in the compartment 82c is also “0”), the pressure in the compartment 82a is “low” and the pressure in the compartment 82d is “medium”. ”, The movable partition wall 83 is disposed at the boost position as shown in FIG. On the other hand, when the internal combustion engine 17 is in a steady operation state from this state and the discharge pressure of the high-pressure pump 15 becomes sufficient and the pressure in the compartment 82d rises to “high”, the movable partition wall 83 becomes as shown in FIG. As shown, it is placed in a fail-safe position.

  In the present embodiment, the change in the balance of the pressing force in the displacement direction acting on the movable partition wall 83 is based on the pressure relationship between the compartment 82a and the compartment 82d as described above, and the compartment 82b via the pressure control path 62. The pressure can be introduced into and prohibited from being switched by opening and closing the control valve 70. That is, in the present embodiment, it is controlled whether or not the discharge pressure is introduced into the compartment 82b out of the two compartments 82a and 82b on the low pressure side into which the discharge pressure of the low pressure pump 14 is introduced in the pressure chamber 82. It changes based on the opening degree control of the valve 70, in other words, the number of compartments into which the discharge pressure is introduced is changed. Accordingly, in accordance with this change, in the movable partition wall 83, the ratio of the area where the discharge pressure of the low-pressure pump 14 acts to the area where the pressure of the discharge side of the high-pressure pump 15 acts (ratio of the action area) is changed. As a result, the aforementioned pressing force balance is changed.

  In this embodiment, the control valve 70 is set to “open (fully opened in this embodiment)”, the pressure “low” acts on both the pressure receiving surfaces 83a and 83b, and the pressure “ The above-mentioned areas Aa to Ad are set so that the movable partition wall 83 is disposed at the original position when the pressure “high” acts on “0” and the high pressure side pressure receiving surface 83d. However, when the discharge pressure of the high-pressure pump 15 is accompanied by pulsation, the above-described arrangement is set at the center value of the discharge pressure.

  Further, as shown in FIGS. 2A to 2C, the movable partition wall 83 includes a first low pressure side pressure receiving surface 83a and a high pressure side pressure receiving surface that constitute a high pressure relief valve mechanism as in the first embodiment. A relief passage 83f communicating with 83d, a ball valve 83g, and a compression spring 83h are provided. Thereby, it is possible to suppress an increase in pressure on the discharge side of the high-pressure side pump 15 through pressure introduction (pressure release) from the high-pressure side pressure receiving surface 83d side to the first low-pressure side pressure receiving surface 83a side via the relief passage 83f. Become.

  Next, the autonomous pressure control mode of the pressure path through the mechanical and autonomous opening control of the control valve 70 based on the pressure on the discharge side of the high-pressure pump 15 in the fuel supply path 13 is shown in FIG. This will be described below using the matrix M201. In the figure, “82a” to “82d” and “S” in the “pressure state” column correspond to the compartments 82a to 82d and the pressure detection unit S in the same order, and “70” and “70” in the “valve open / close state” column “83g” corresponds to the control valve 70 and the ball valve 83g in the same order.

  First, since both pumps 14 and 15 are in a drive stop state before the engine is started, the pressures in the branch chambers 82a to 82d and the pressure detecting section S are “0”. At this time, since the pressure of the pressure detecting section S is “0”, the control valve 70 is “closed (in the present embodiment, fully closed state)”. In the booster 60, the movable partition wall 83 is disposed at the original position, and the ball valve 83g is “closed” because there is no pressure difference between the branch chamber 82a and the branch chamber 82d.

  When the internal combustion engine 17 is started from this state (starting time 1), the drive of both pumps 14 and 15 is started, and the pressures of the compartments 82a and 82d and the pressure detecting section S become “low” immediately after the start of the drive. . The reason why the pressure of the pressure detecting section S is “low” at this point is that there is no pressure increase due to the high-pressure side pump 15 since the drive has started. Here, the displacement of the movable partition wall 83 to the boost position is started by the pressure in the compartment 82a rising to “low”.

  As the movable partition wall 83 is displaced, the pressure in the compartment 82d is increased to “medium” (boost pressure), and fuel is supplied to the high-pressure reservoir 21 at this pressure (starting time 2). That is, due to the displacement of the movable partition wall 83, the injection pressure of the injector 12 is rapidly increased at a speed exceeding the increase speed of the discharge pressure of the high-pressure pump 15. As the pressure in the branch chamber 82d rises, the pressure in the pressure detecting section S increases to “medium”, that is, becomes higher than “low”, so that the control valve 70 is “open”.

  When the discharge pressure of the high-pressure pump 15 reaches the aforementioned “high” with the passage of time from the start of driving of the internal combustion engine 17, the pressure in the compartment 82 d becomes “high” accordingly (during steady operation 1). . In this embodiment, if the control valve 70 is “closed” (the pressure in the compartment 82b is “0”), the pressure in the compartment 82d is “high” and the pressure in the compartment 82a is “low” ( However, the pressure in the compartment 82c is “0”), and the movable partition wall 83 is disposed at the fail-safe position. However, in the “normal operation 1”, the control valve 70 is “open” in the “start 2” described above, so that the pressure in the compartment 82b is “low”. Therefore, in this case, the movable partition wall 83 is disposed not at the fail-safe position but at the original position from the boost position.

  In the state where the movable partition wall 83 is disposed at the original position during the steady operation of the internal combustion engine 17, the pressure fluctuation on the discharge side of the high-pressure pump 15 generated in the fuel supply path 13 is suppressed by the booster 60. (At the time of steady operation 2). This pressure fluctuation is caused by the influence of the fluctuation of the rotational speed of the internal combustion engine 17 and the pulsation of the discharge pressures of both pumps 14 and 15. That is, the movable partition wall 83 moves (displaces) between the boost position and the fail-safe position in the pressure chamber 82 in accordance with the pressure fluctuation in the pressure chamber 82 acting on the movable partition wall 83, so that the high-pressure pump 15 described above. It functions to suppress pressure fluctuation on the discharge side.

  For example, when the pressure of the discharge side of the high-pressure pump 15, that is, the pressure in the compartment 82 d fluctuates from the state where the movable partition wall 83 is stationary at the original position, the pressing force balance in the displacement direction acting on the movable partition wall 83 is biased and the same. Since the movable partition wall 83 is displaced to the boost position side, further pressure drop in the compartment 82d is suppressed. This pressure drop suppression can be performed until the movable partition wall 83 reaches the boost position.

  On the other hand, for example, when the pressure on the discharge side of the high-pressure pump 15, that is, the pressure in the compartment 82 d changes in the upward direction from the state where the movable partition 83 is stationary at the original position, the pressing force balance in the displacement direction acting on the movable partition 83 is When the movable partition wall 83 is displaced in the opposite direction to that described above and is displaced toward the fail-safe position, further pressure increase in the compartment 82d is suppressed. The suppression of the pressure increase accompanying the displacement of the movable partition wall 83 can be performed until the movable partition wall 83 reaches the fail safe position.

  That is, it can be said that the booster 60 has a function (pressure fluctuation suppressing function) for suppressing pressure fluctuation on the injector 12 side based on such displacement of the movable partition wall 83. Then, the control valve 70 changes the ratio of the working area in the movable partition wall 83 based on the mechanical and autonomous opening degree control so that the function of the booster 60 is introduced to the injector 12 side as described above. The function is switched between a function for performing (boost function) and the pressure fluctuation suppressing function.

  If the pressure increase in the aforementioned compartment 82d is so large that it cannot be absorbed by the displacement of the movable partition wall 83 (the pressure at this time is referred to as “ultra-high”), the ball valve 83g is opened (valve The relief passage 83f is in communication and is separated from the seat, and the pressure in the compartment 82d is introduced into the compartment 82a through the passage 83f, that is, the pressure is released (at an abnormally high pressure). Thereby, an excessive pressure rise in the compartment 82d is avoided.

  Then, when the internal combustion engine 17 is stopped and both pumps 14 and 15 are stopped, in this embodiment, immediately after the stop, the pressure in the pressure detection section S and the compartment 82d exhibits “high” and the compartment 82a. , 82b are “low” (1 when stopped). With such a pressure state, the movable partition wall 83 is disposed at the original position. Then, as time elapses after the internal combustion engine 17 is stopped, the pressure in the pressure path becomes “0”, and the movable partition wall 83 is held at the original position (2 when stopped). When the pressure is reduced, the control valve 70 is “closed” because the pressure of the pressure detecting section S is “low” or lower.

  In the present embodiment, as in the first embodiment, the use of both the boost function and the pressure fluctuation suppression function in the booster 60 is changed by changing the pressing force balance in the displacement direction acting on the movable partition wall 83. Is possible. Accordingly, by using both these functions properly according to, for example, the pressure state at the discharge port 20 of the fuel supply passage 13, the rate of increase in the fuel injection pressure of the injector 12 is improved, and during steady operation of the internal combustion engine 17. Thus, the pulsation of the fuel injection pressure can be suitably suppressed.

In the present embodiment, in addition to the same effects as the above (2) and (3), the following effects can be obtained.
(4) Based on the opening degree control of the control valve 70, the discharge side of the high-pressure pump 15 relative to the movable partition wall 83 is changed by changing the number of compartments (compartments 82a and 82b) into which the discharge pressure of the low-pressure pump 14 is introduced. The ratio of the working area between the pressure of the pressure and the discharge pressure of the low-pressure side pump 14 is changed. According to this, the pressing force balance can be changed based on the change in the ratio of the acting areas of both pressures of the movable partition wall 83, and both functions of the booster 60 can be switched.

  (5) The control valve 70 is an autonomous control valve whose opening degree can be changed mechanically and autonomously according to the pressure on the discharge side of the high-pressure pump 15. According to this, each said function of the booster 60 and switching of these functions can be made suitable according to the pressure of the discharge side of the high-pressure side pump 15. In addition, for example, a control valve can be used in other ways by using a sensor to detect the pressure on the discharge side of the high-pressure pump 15 or using a control device such as a CPU that performs a calculation based on the detection result of the sensor. Compared with the aspect like the first embodiment in which the opening degree control is performed, it is not necessary to provide such a sensor and a control device, so the configuration becomes simple.

In addition, embodiment is not limited above, For example, it is good also as the following aspects.
In the first embodiment, for example, the other pressure sensors 35 may be omitted except for the pressure sensors 35d and 35g. The detection result by the pressure sensor 35d is referred to at the time of opening control of the control valves 30A to 30D for disposing the movable partition wall 53 in the original position at the time of starting 2 described above. Further, the pressure sensor 35g is referred to at the time of opening control of the control valves 30A to 30D for displacing the movable partition wall 53 in order to maintain the injection pressure of the injector 12 appropriately in the above-described steady operation 1 and 2. At the time of starting 2 described above, the opening degree control of the control valves 30A to 30D for placing the movable partition wall 53 in the original position is performed based on the detection result of the pressure sensor 35d. For example, the same opening degree control may be performed based on the detection results of the pressure sensor 35b and the pressure sensor 35c. In this case, the pressure sensor 35d may be omitted in place of the pressure sensors 35b and 35c where the detection result is referred to.

In the second embodiment, the pressure sensor 35g may be omitted.
In the first and second embodiments, the high pressure relief valve mechanism may be omitted.
In the second embodiment, the control valve 70 is a so-called autonomous control valve. However, instead of this, for example, a pressure sensor for detecting the pressure of the pressure detection unit S is provided, and electronic control based on the detection result of the sensor is provided. The pressure control path 62 may be opened and closed by a control valve whose opening degree is controlled by a command from the apparatus.

  In the second embodiment, on the low pressure side pressure receiving surfaces (first and second low pressure side pressure receiving surfaces 83a and 83b), the action area of the discharge pressure of the low pressure side pump 14 is switched to two stages, but three or more stages You may make it switch to.

  In the second embodiment, the working area of the discharge pressure of the low pressure pump 14 is switched on the low pressure side pressure receiving surfaces (first and second low pressure side pressure receiving surfaces 83a and 83b). You may make it switch the action area of the pressure of the discharge side of the high pressure side pump 15 in a pressure receiving surface. In addition, each working area may be switched on the pressure receiving surfaces on both the high pressure side and the low pressure side.

In the opening control of the control valves 30A to 30D, 70, the opening control may be performed so that the opening is not limited to a configuration in which the valve is fully opened and fully closed, but is changed between the opening other than the fully opened and fully closed.
By changing the ratio of the pressure acting on the high pressure side pressure receiving surfaces 53c, 83d and the pressure acting on the low pressure side pressure receiving surfaces 53a, 83a, 83b based on autonomous opening control of the control valve, the movable partition wall You may make it change the pressing force balance which acts on 53,83. In this case, for example, in the second embodiment, the control valve 70 is moved on the first booster path 61a, and the passing cross-sectional area of the first booster path 61a in this portion is changed and controlled. At this time, the pressure control path 62 is omitted, and the compartment 82b is in a state of communicating only with the compartment 82a in the housing 81, for example. Then, the passage cross-sectional area of the first booster path 61a is changed by the autonomous opening degree control of the control valve 70 based on the pressure of the pressure detection unit S. In the above opening degree control, the opening degree of the control valve 70 may be switched between full opening and full closing, or may be changed between opening degrees other than full opening and full closing.

-Although the rotary type was used for both pumps, it is not restricted to this, For example, the reciprocating type provided with the piston etc. may be used.
The drive source for both pumps 14 and 15 may be other than the internal combustion engine 17, for example, an electric motor provided separately from the internal combustion engine 17.

  In the first and second embodiments, two pumps such as the low-pressure side pump 14 and the high-pressure side pump 15 are provided, but not limited to this, three or more pumps may be arranged in series in the pressure path. In this case, for example, in the pump other than the pump provided on the lowest pressure side in the pressure path, the suction port and the discharge port may be communicated with each other through the booster path. The discharge ports may be communicated with each other through a booster route.

  In the above embodiment, the present invention is applied to a fuel injection device for an internal combustion engine. However, for example, the fuel injection device may be used for supplying other fuel or for supplying fluid other than fuel.

The block diagram which shows the outline | summary of the multistage pump system of 1st Embodiment. (A), (b), (c), (d) is sectional drawing which shows a booster. The control matrix for demonstrating the opening / closing control of the control valve by ECU. The graph which shows the relationship between an engine speed and the injection pressure of an injector. The block diagram which shows the outline | summary of the multistage pump system of 2nd Embodiment. (A), (b), (c) is sectional drawing which shows a booster. The control matrix for demonstrating the autonomous opening / closing control of a control valve.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Injector, 13 ... Fuel supply path, 14 ... Low pressure side pump, 15 ... High pressure side pump, 19 ... Return path, 20 ... Discharge port, 30A, 30B, 30C, 30D, 70 ... Control valve, 40, 60 ... Booster 41, 61 ... Booster path, 42 ... Pressure adjustment path, 43, 64 ... Drain path, 52, 82 ... Pressure chamber, 53, 83 ... Movable partition, 53a ... Low pressure side pressure receiving surface, 53c, 83d ... High pressure side pressure receiving surface 53d, 83f ... relief passage, 53e, 83g ... ball valve, 53f, 83h ... compression spring, 62 ... pressure control path, 82a, 82b ... compartment, 83a ... first low pressure side pressure receiving surface, 83b ... second low pressure side pressure receiving Surface, Aa, Ab, Ad ... projected area.

Claims (9)

A plurality of pumps arranged in series in the pressure path from the suction side to the discharge side;
A movable partition that can receive the discharge pressure of the low-pressure side pump among the pumps is built-in, and the movable partition is displaced by receiving the discharge pressure, so that a boost pressure higher than the discharge pressure can be generated. In a multi-stage pump system including a booster capable of supplying the boost pressure to the discharge side of the high-pressure pump in the pressure path,
A control valve whose opening degree is controlled to change the passage cross-sectional area of the pressure path is provided,
A balance between the pressing force acting on the movable partition based on the pressure on the discharge side of the high-pressure pump and the pressing force acting on the movable partition based on the discharge pressure of the low-pressure pump is used for opening control of the control valve. The booster function is changed based on the boost function for introducing the boost pressure to the discharge side of the high-pressure pump, and the movable partition is displaced with the pressure fluctuation on the discharge side of the high-pressure pump. The multi-stage pump system is configured to switch between the pressure fluctuation suppressing function for suppressing the pressure fluctuation. The multistage pump system according to claim 1, wherein the balance of the pressing force is changed by changing a ratio of the two pressures acting on the movable partition wall based on the opening degree control. The multistage pump system according to claim 1, wherein the balance change of the pressing force is performed by changing a ratio of an action area of each pressure to the movable partition wall based on the opening degree control. The movable partition constitutes a high pressure side pressure receiving surface constituting an inner wall surface of a pressure chamber into which pressure on the discharge side of the high pressure side pump is introduced, and an inner wall surface of a pressure chamber into which discharge pressure of the low pressure side pump is introduced. And at least one of the pressure chambers is partitioned into a plurality of compartments with the pressure receiving surface corresponding to the pressure chamber as an inner wall surface, and the ratio change of the working area is the same pressure. The multistage pump system according to claim 3, wherein the multistage pump system is performed by changing the number of the compartments into which the pressure is introduced in the chamber based on the opening degree control. The control valve according to any one of claims 1 to 4, wherein the control valve is a right-handed control valve whose opening degree can be freely changed by an external command signal based on a pressure on a discharge side of the high-pressure side pump. Multistage pump system. The multistage pump system according to any one of claims 1 to 4, wherein the control valve is an autonomous control valve whose opening degree can be mechanically and autonomously changed according to a pressure on a discharge side of the high-pressure pump. A relief passage communicating the high pressure side pressure receiving surface receiving the pressure on the discharge side of the high pressure side pump and the low pressure side pressure receiving surface receiving the discharge pressure of the low pressure side pump in the movable partition, and a valve capable of opening and closing the passage A multi-stage relief valve mechanism according to any one of claims 1 to 6, further comprising a high-pressure relief valve mechanism capable of suppressing a pressure increase on the discharge side of the high-pressure pump through pressure relief via the relief passage. Pump system. The multistage pump system according to any one of claims 1 to 7, wherein a rotary type pump is used as the pump. The multistage pump system according to any one of claims 1 to 8, wherein an injector for supplying fuel is connected to a discharge port of the pressure path.

Images