EP2942517A1

EP2942517A1 - Fuel supply control device

Info

Publication number: EP2942517A1
Application number: EP15162354.3A
Authority: EP
Inventors: Akihiro Kuroda
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2014-04-17
Filing date: 2015-04-02
Publication date: 2015-11-11
Anticipated expiration: 2035-04-02
Also published as: EP2942517B1; JP2015206266A

Abstract

A first electromagnetic valve (100) closes an inflow port (121) and that a plunger (11) slides in a pump chamber (12), thereby compressing fuel flowing into the pump chamber (12) and discharging the fuel to the outside. The fuel supply control device includes a number-of-revolutions sensor (51) for sensing the number of revolutions (R) of a camshaft (8). In a case where a discharge instruction signal is not turned on and where the number of revolutions (R) sensed by the number-of-revolutions sensor (51) is not less than a specified number of revolutions (Rth), even in a case where the fuel does not need to be discharged to the outside, a controller (5) closes the first electromagnetic valve (100) in such a way that the plunger 11 compresses the fuel.

Description

The present invention relates to a fuel supply control device for compressing fuel and for supplying the fuel to an internal combustion engine.
In an internal combustion engine such as a diesel engine has been known a fuel supply control device such as a high-pressure fuel pump for compressing fuel to a high pressure and for discharging the fuel to the outside. The high-pressure fuel pump is provided with a pump chamber having an inflow port connected to a fuel tank and a discharge port connected to an outside common rail or the like. The pump chamber has a plunger sliding therein. The plunger abuts on a camshaft which is rotated by power received from the internal combustion engine. When the camshaft is rotated, the plunger abutting on the camshaft is pressed by a protruding portion formed on the outer periphery of the camshaft, whereby the rotational force of the camshaft is transformed into a force in a direction in which the plunger slides and hence the plunger is slid. Then, when the inflow port is closed and the plunger is slid, the fuel flowing into the pump chamber from the inflow port is compressed. Then, the fuel, which is compressed and is brought into high pressure, is discharged to a common rail.
In the high-pressure fuel pump like this, there has been known a pump having an electromagnetic amount regulation valve provided in an inflow port so as to regulate the amount of the fuel flowing into the pump chamber. The electromagnetic amount regulation valve has its closing operation and opening operation controlled by an external control unit. For example, a high-pressure fuel pump shown in JP-2011-202549A has an electromagnetic amount regulation valve provided in an inflow port.
In the high-pressure fuel pump like this, it is necessary to hold a state where the plunger abuts on the camshaft so as to efficiently slide the plunger. When the fuel is compressed by the plunger in the pump chamber, a resultant force of the pressure in the pump chamber, a pressing force of a spring provided on the outer periphery of the plunger, and an inertia force by the mass of a movable part of the plunger and, in addition, load by a plunger spring are applied to the plunger. In this way, a force of pressing the plunger in a direction of the camshaft is produced, so the plunger is hard to separate from the camshaft. At this time, it is the pressure in the pump chamber that greatly contributes to the force of pressing the plunger in the direction of the camshaft. On the other hand, in a case where the fuel is not compressed by the plunger, the force of pressing the plunger onto the camshaft is the inertia force by the mass of the movable part of the plunger and the pressing force of the spring. Hence, as the number of revolutions of the camshaft is increased, the rotation speed of the camshaft becomes larger than a speed at which the plunger follows and slides on the surface of the camshaft, which hence causes a possibility that the plunger might temporarily separate from the camshaft. In a case where the plunger temporarily separates from the camshaft, when the plunger again abuts on the camshaft, noises are likely to be caused to impair the silence of the high-pressure fuel pump.
An object of the present invention is to provide a fuel supply control device that prevents a plunger from separating from a camshaft and that has a high degree of silence.
According to one aspect of the present invention, a fuel supply control device includes a pump chamber having an inflow port and a discharge port; a first electromagnetic valve for closing the inflow port; a check valve which is provided in the discharge port; a control means for closing the first electromagnetic valve; a camshaft which receives power from an internal combustion engine; and a plunger which slides in the pump chamber. When the first electromagnetic valve closes the inflow port and the plunger is slid up in the pump chamber, the fuel flowing into the pump chamber is compressed. The fuel supply control device includes a number-of-revolutions sensing means for sensing a number of revolutions of the camshaft. When a discharge instruction signal is not turned on and the number of revolutions sensed by the number-of-revolutions sensing means is not less than a specified number of revolutions, the control means closes the first electromagnetic valve in such a way that the plunger compresses the fuel.
Even in a case where the discharge instruction signal is not turned on and the first electromagnetic valve does not need to be closed, when the number of revolutions of the camshaft is not less than the specified number of revolutions, the control means determines that the plunger is likely to separate from the camshaft and sends a signal to the first electromagnetic valve to compress the fuel by the plunger. The compressed fuel biases the plunger toward the camshaft side, whereby the state where the plunger abuts on the camshaft can be held. Hence, in the case where the discharge instruction signal is not turned on, it is possible to hold the state where the plunger abuts on the camshaft.
As described above, it is possible to provide the fuel supply control device that prevents the plunger from separating from the camshaft and that has a high degree of silence.
The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings.

Fig. 1 is a general schematic diagram to show a fuel supply control device in a first embodiment.
Fig. 2 is a schematic view to show a high-pressure fuel pump in the first embodiment.
Fig. 3 is a graph to show an acceleration of a plunger in response to a cam profile and a camshaft when a high-pressure fuel pump compresses fuel, pressure in a plunger chamber, and a valve lift timing of an electromagnetic amount regulation valve.
Fig. 4 is an illustration to show a flow chart performed by a control device in the first embodiment.
Fig. 5 is a schematic view to show a high-pressure fuel pump in a second embodiment.
Fig. 6 is an illustration to show a flow chart performed by a control device in the second embodiment.
Fig. 7 is an illustration to show a flow chart performed by a control device in a third embodiment.

Hereinafter, embodiments of the present invention will be described on the basis of the drawings. Corresponding constituent elements in the embodiments are designated by the same reference characters and there are cases where their duplicate descriptions are omitted. Further, in the descriptions of the embodiments, in addition to the combination of constructions described clearly, the embodiments and modified examples can be also combined with each other if their combinations do not pose a problem.

(First Embodiment)

A fuel supply control device of the present embodiment will be described by the use of Fig. 1 to Fig. 5.
As shown in Fig. 1, the fuel supply control device of the present embodiment includes a fuel tank 6, a common rail 3, an ECU 5, a high-pressure fuel pump 1 connected to a camshaft 8, and the like.
The fuel tank 6 is a tank for storing fuel and is connected to the high-pressure fuel pump 1 via a low-pressure supply passage 71. Further, the low-pressure supply passage 71 has a feed pump 2 provided therein. The feed pump 2 has a function of supplying the fuel in the fuel tank 7 to the high-pressure fuel pump 1. The feed pump 2 is a known low-pressure pump for sucking the fuel by using the power of an internal combustion engine.
The common rail 3 is a cylindrical container for accumulating the fuel compressed by the high-pressure fuel pump 1. The common rail 3 is connected to the high-pressure fuel pump 1 via a high-pressure supply passage 72. The fuel compressed by the high-pressure fuel pump 1 is sent under pressure to the common rail 3 via the high-pressure supply passage 72. Further, the common rail 3 is connected to injectors 4 provided in respective cylinders, and the fuel compressed by the high-pressure fuel pump 1 is accumulated in the common rail 3 and then is distributed to the respective injectors 4.
Further, the common rail 3 has a first pressure sensor 32 and a regulation valve 31 provided therein. The first pressure sensor 32 is a sensor for sensing the pressure of the fuel accumulated in the common rail 3. The first pressure sensor 32 is connected to the ECU 5 and sends the sensed pressure in the common rail 3 (hereinafter referred to as rail pressure Pr) to the ECU 5. The regulation valve 31 is a valve body for discharging the fuel in the common rail 3 to the outside. Further, the regulation valve 31 is connected to the fuel tank 6 via a leak passage 73.
The regulation valve 31 receives a signal from the ECU 5 and outputs the fuel to the outside, thereby being able to regulate the rail pressure Pr at a specified pressure. That is, the regulation valve 31 is normally closed, and in a case where the rail pressure Pr sensed by the first pressure sensor 32 is higher than a desired pressure value, the regulation valve 31 receives a valve opening signal from the ECU 5 and has current passed therethrough, thereby being opened. In this way, the common rail 3 communicates with the leak passage 73, whereby the fuel is returned to the fuel tank 6 via the leak passage 73 to thereby reduce the rail pressure Pr. In other words, the regulation valve 31 is an electromagnetic valve which is normally closed and corresponds to a second electromagnetic valve.
The camshaft 8 is connected to a crankshaft in such a way as to rotate with the crankshaft rotated by power given from the combustion energy of the internal combustion engine. The camshaft 8 is provided with a number-of-revolutions sensor 51. The number-of-revolutions sensor 51 is connected to the ECU 5 and sends the number of revolutions of the camshaft 8 to the ECU 5. The number-of-revolutions sensor 51 is a known sensor for sensing of the number of revolutions of the camshaft 8 from a timing rotor and a cam angle sensor. Further, in place of providing a camshaft with a number-of-revolutions sensor, it is also recommended to provide a crankshaft with a crank angle sensor and to sense the number of revolutions of the crankshaft from a timing rotor and the crank angle sensor and to calculate the number of revolutions of the camshaft from the number of revolutions of the crankshaft. In this way, the ECU 5 can sense the number of revolutions of the camshaft 8. That is, the number-of-revolutions sensor 51 corresponds to a number-of-revolutions sensing means.
Further, the camshaft 8 has a plurality of protruding portions and a plurality of depressing portions formed on its outer periphery, the plurality of protruding portions having their surfaces protruded to the outside in a radial direction, the plurality of depressing portions being formed between the plurality of protruding portions and being depressed to the inside in the radial direction as compared with the protruding portions. The protruding portions and the depressing portions are formed smoothly and continuously on the surface of the camshaft 8.
Next, the high-pressure fuel pump 1 will be described in detail by the use of Fig. 2.
As shown in Fig. 2, the high-pressure fuel pump 1 is constructed of: a cylindrical housing body 10; a pump chamber 12 formed in the housing body 10; an electromagnetic amount regulation valve 100 for regulating an amount of the fuel flowing into the pump chamber 12; a plunger 11 sliding in the pump chamber 12; the camshaft 8 abutting on the plunger 11; and the like.
In the housing body 10 are formed a first passage 14 in which the low pressure fuel flows and a second passage 15 in which the high pressure fuel flows. The first passage 14 and the second passage 15 communicate with the pump chamber 12.
In the pump chamber 12 are formed an inflow port 121 through which the fuel from the first passage 14 flows in and a discharge port 122 from which the fuel is discharged to the second passage 15. Further, the pump chamber 12 has the plunger 11 inserted thereinto. Still further, the first passage 14 is connected to the low-pressure supply passage 71 and the second passage 15 is connected to the high-pressure supply passage 72.
The plunger 11 is constructed of a tappet body 112, a roller 111, and a sliding part 110. The sliding part 110 is a columnar member and is formed in a diameter smaller than an inner diameter of the cylinder of the pump chamber 12. The sliding part 110 is a part which slides on the interior of the pump chamber 12 in the plunger 11 and which directly compresses the fuel. On the camshaft 8 side of the sliding part 110 is integrally formed the tappet body 112 of holding the roller 111. The tappet body 112 has a cylindrical depressed portion formed on the camshaft 8 side thereof and the roller 111 is rotatively held by the depressed portion. The roller 111 is shaped like a column and abuts on the camshaft 8 at the outer peripheral surface of the column. When the camshaft 8 rotates, the roller 111 rotates along with the camshaft 8.
Further, the sliding part 110 has a first spring 113 provided on its outer periphery. The first spring 113 is provided between the tappet body 112 and the housing body 110 and applies a biasing force to the tappet body 112 to thereby normally bias the plunger 11 to the camshaft 8 side. In this way, the first spring 113 prevents the roller 111 provided on the camshaft 8 side of the plunger 11 from separating from the camshaft 8.
When the camshaft 8 rotates, the plunger 11 constructed of the tappet body 112, the roller 111, and the sliding part 110 moves up and down in the pump chamber 12. In other words, the camshaft 8 has the protruding portions and the depressing portion formed thereon as described above, so when the camshaft 8 rotates, the protruding portions and the depressing portions alternately abut on the roller 111. The rotation of the camshaft 8 is transformed into a force in a sliding direction in which the plunger 11 slides by the protruding portions and the depressing portions, whereby the plunger 11 moves up and down in the sliding direction in the pump chamber 12.
The pump chamber 12 has the electromagnetic amount regulation valve 100 provided in the inflow port 121 thereof. The electromagnetic amount regulation valve 100 is constructed of a solenoid 106, an armature 101 attracted by the solenoid 106, a second spring 108, and the like.
The solenoid 106 is a cylindrical member formed of a wound cord. When current is passed through the solenoid 106, the solenoid 106 forms a magnetic path. When the magnetic path is formed, the armature 101 is attracted by the solenoid 106. The solenoid 106 is electrically connected to an electricity storage means such as a battery (not shown in the drawing). Further, between the solenoid 106 and the electricity storage means is provided a switch circuit 140 which, when receiving a signal from the ECU 5, passes current through the solenoid 106 or interrupts a circuit. The solenoid 106 has a third spring 105 and a stopper 107 provided in its cylinder. The stopper 107 abuts on the armature 101 on its tip end side of a pump chamber 12 side and abuts on the third spring 105 on its base end side opposite to the tip end side. Further, the third spring 105 abuts on the body on its base end side.
With this construction, the stopper 107 is normally biased to the pump chamber 12 side by the third spring 105. By the stopper 107 biased by the third spring 105, the armature 101 is normally biased to the pump chamber 12 side.
The armature 101 is constructed of a circular disc portion 102, a rod portion 104, and a valve body portion 103. The circular disc portion 102, which is formed on a base end side opposite to the pump chamber 12 side of the armature 101, is a portion made of a steel material and attracted by the solenoid 106. The rod portion 104 is a columnar portion which is extended to a tip end side from the radial center of a tip end side face that is the pump chamber 12 side of the circular disc portion 102. Further, the rod portion 104 is formed in a diameter smaller than the diameter of the first passage 14 and is provided in such a way as to extend in the first passage 14 from the inflow port 121 on the pump chamber 12 side.
The valve body portion 103 is provided on the pump chamber 12 side of the rod portion 104. Further, the valve body portion 103 is provided on the pump chamber 12 side of the inflow port 121 in which the first passage 14 opens in the pump chamber 12. The valve body portion 103 has a cross section in an axial direction formed in a circle and has a diameter larger than the diameter of the inflow port 121. When the armature 101 which is integrally formed of the circular disc portion 102, the rod portion 104, and the valve body portion 103 is attracted by the solenoid 106, the armature 101 is moved to the solenoid 106 side. At this time, since the valve body portion 103 formed on the tip end side of the rod portion 104 has the diameter larger than the diameter of the inflow port 121, when the armature 101 is moved to the solenoid 106 side, the armature 101 abuts on the housing body 10 and hence closes the inflow port 121.
The second spring 108 is interposed between the circular disc portion 102 of the armature 101 and the housing body 10. The second spring 108 biases the circular disc portion 102 to a side opposite to the pump chamber 12 side. When the third spring 105 is compared with the second spring 108 in the biasing force, the third spring 105 is made larger in the biasing force than the second spring 108. In this way, a force of biasing the armature 101 to the pump chamber 12 side by the third spring 105 and the stopper 107 is larger than a force of biasing the armature 101 to the pump chamber 12 side by the second spring 108, so that in a case where the armature 101 is not attracted by the solenoid 106, the valve body portion 103 formed at the tip end of the armature 101 opens the inflow port 121. In other words, the electromagnetic amount regulation valve 100 constructed of the armature 101, the solenoid 106, and the like is an electromagnetic valve which is normally opened, that is, which normally opens the inflow port 121 and which, when current is passed through the solenoid 106, seals the inflow port 121. The electromagnetic amount regulation valve 100 corresponds to a first electromagnetic valve.
The second passage 15 communicating with the pump chamber 12 is provided with a check valve 13 for preventing the fuel from flowing reversely from the common rail 3 provided on the outside of the high-pressure fuel pump 1. The check valve 13 is constructed of a ball body 131 which is formed in a diameter larger than a diameter of the second passage 15 and a fourth spring 132 which normally biases the ball body 131 to the pump chamber 12 side. When the pressure in the pump chamber 12 is larger than a resultant force of the rail pressure Pr and the biasing force of the fourth spring 132 (specified valve opening pressure Prev), the check valve 13 has the ball body 131 and the fourth spring 132 biased to a side opposite to the pump chamber 12 side, whereby the ball body 131 opens the second passage 15. In this way, the second passage 15 communicates with the high-pressure fuel passage 72 connected to the common rail 3, whereby the fuel is discharged to the common rail 3 from the pump chamber 12. On the other hand, in a case where the pressure in the pump chamber 12 is smaller than the resultant force of the rail pressure Pr and the specified valve opening pressure Prev of the fourth spring 132, the check valve 13 is not opened and hence the fuel is not discharged to the common rail 3 from the pump chamber 12.
The ECU 5 is a processor circuit constructed of a volatile memory and an operation unit. The ECU 5 is electrically connected to the regulation valve 31 of the common rail 3, the first pressure sensor 32, the number-of-revolutions sensor 51 of the camshaft 8, and the switch circuit 140. Further, although not shown in the drawing, the ECU 5 is connected also to the injector 4 and an accelerator opening sensor for sensing an opening of an accelerator pedal. The ECU 5 calculates a necessary fuel injection amount according to the opening of the accelerator sensed by the accelerator opening sensor connected to the accelerator pedal and sends a throttle opening command to a throttle for regulating an air amount to be sucked and sends an injection command to the injector 4.
At this time, in order to regulate the pressure of the fuel injected from the injector 4, the ECU 5 reads the rail pressure Pr from the first pressure sensor 32 and calculates the amount of the fuel to be discharged to the common rail from the high-pressure fuel pump 1 on the basis of the rail pressure Pr. Then, the ECU 5 turns ON a valve closing signal Sc to the switch circuit 140 connected to the solenoid 106 on the basis of a specified necessary fuel amount to be discharged to the common rail 3 from the high-pressure fuel pump 1. In this way, the switch circuit 140 passes the current through the solenoid 106 to thereby close the electromagnetic amount regulation valve 100. Further, after a necessary valve opening period passes, the ECU 5 turns OFF the valve closing signal Sc to the switch circuit 140. In this way, the switch circuit 140 stops passing the current through the solenoid 106 to thereby open the electromagnetic amount regulation valve 100. That is, the ECU 5 corresponds to a control means.
Next, how the electromagnetic amount regulation valve 100 is activated on the basis of the amount of the fuel which the high-pressure fuel pump 1 discharges to the outside will be described by the use of Fig. 3.
As shown in Fig. 3, a flag of a pump discharge instruction for instructing the high-pressure fuel pump 1 to discharge the fuel is turned ON in the ECU 5. In other words, when the flag of the pump discharge instruction is turned ON, a discharge amount to be sent to the common rail 3 by the high-pressure fuel pump 1 is calculated and the valve closing signal Sc to the switch circuit 140 is operated so as to satisfy the discharge amount. That is, the pump discharge instruction corresponds to a discharge command signal. That the discharge command signal is not provided indicates that the flag of the pump discharge instruction is turned OFF.
In Fig. 3, the lateral axis indicates time t and the vertical axis indicates in the following order from above: pump discharge instruction signal (0 or 1); cam profile when the camshaft 8 is rotated; acceleration of the plunger 11 in a direction in which the plunger 11 slides; pressure in the pump chamber 12; and valve closing instruction signal to the electromagnetic amount regulation valve 100.
The electromagnetic amount regulation valve 100 is normally opened, so that the fuel normally flows into the pump chamber 12. While the electromagnetic amount regulation valve 100 is opened, even if the plunger 11 is slid, the fuel is discharged from the inflow port 121. Here, when the ECU 5 determines that the discharge amount of the high-pressure fuel pump 1 is insufficient in a period during which the pump discharge instruction signal rises (period from time 0 to time To), the ECU 5 sends a valve closing signal for closing the electromagnetic amount regulation valve 100 to the electromagnetic amount regulation valve 100. The period during which the pump discharge instruction signal rises means a period during which it is determined that the fuel needs to be sent to the injector 4 from the high-pressure fuel pump 1, for example, a period from when the flag of the pump discharge instruction is turned ON by an accelerator pedal being pressed down until when the flag of the pump discharge instruction is turned OFF by the accelerator pedal being released. The ECU 5 turns ON the valve closing signal to the switch circuit 140 in the period, whereby current is passed through the solenoid 106. In this way, the solenoid 106 attracts the armature 101, whereby the electromagnetic amount regulation valve 100 closes the inflow port 121 (time Ta1).
When the inflow port 121 is closed by the electromagnetic amount regulation valve 100, the pump chamber 12 is tightly closed and then the plunger 11 is moved up to thereby start to compress the fuel flowing in the pump chamber 12. The valve body portion 103 of the armature 101 seals the inflow port 121, so that as the plunger 11 is further moved in a sliding direction so as to reduce volume in the pump chamber 12, the fuel is further compressed and the pressure of the fuel is further increased. When the pressure of the fuel in the pump chamber 12 becomes larger than the resultant force of the biasing force of the check valve 13, which is provided in the second passage 15 communicating with the discharge port 122, and the rail pressure Pr, the check valve 13 is opened (time Ta2). In this way, the fuel is discharged to the outside from the pump chamber 12. Here, during a period from the time Ta2 to time Ta3, the check valve 13 is opened and hence a tightly closed state in the pump chamber 12 is relieved, so that although the fuel is being compressed, the fuel is supplied to the common rail 3 from the discharge port 122 and hence the pressure in the pump chamber 12 is held at a constant pressure.
Then, when the time Ta3 is reached when the plunger 11 is moved to a position at which the volume of the pump chamber 12 becomes minimal (so-called top dead center of the plunger) in the pump chamber 12, the plunger 11 starts to be moved down in the pump chamber 12 and hence the pressure of the fuel in the pump chamber 12 starts to be decreased. Then, when the pressure of the fuel in the pump chamber 12 becomes not more than the biasing force of the check valve 13, the check valve 13 is closed to stop supplying the fuel to the outside. Further, when the passing of the current through the solenoid 106 is finished at time Ta4, the valve body portion 103 of the armature 101 opens the inflow port 121. In this way, the pressure of the fuel in the pump chamber 12 is decreased to the same pressure value as a pressure value of the fuel before being compressed. Then, at time Ta5, the plunger 11 reaches a position at which the volume of the pump chamber 12 becomes maximal (so-called bottom dead center of the plunger) in the pump chamber 12.
As to an acceleration of the plunger 11, as shown in Fig. 3, while the camshaft 8 is rotated once, a plus acceleration and a minus acceleration are produced. In a process from the bottom dead center to the top dead center of a cam profile, when the roller 111 moves from the depressing portion to the protruding portion on the surface of the camshaft 8, a load is applied to the roller 111 in a direction in which the roller 111 is pressed onto the camshaft 8 by a resistant force against a force of the camshaft 8 to press the roller 111 across the depressing portion. That is, at this time, the plus acceleration is applied to the plunger 11. In the next process, while the roller 111 is moving along the protruding portion, the acceleration of the plunger 11 becomes a uniform acceleration, and when the roller 111 comes near to the top dead center of the cam profile, the slant of the protruding portion decreases toward the top of the protruding portion of the camshaft 8 and hence the force of the camshaft 8 to press the roller 111 becomes smaller and a load is applied to the roller 111 in a direction to separate from the camshaft 8. That is, the minus acceleration is applied to the plunger 11. Here, as to the acceleration of the plunger 11 shown in Fig. 3, the acceleration applied from the plunger 11 side to the camshaft 8 side is assumed to be the plus acceleration, whereas the acceleration opposite to this is assumed to be the minus acceleration. In this regard, the acceleration of the plunger 11 shown in Fig. 3 shows an acceleration which the plunger 11 receives from the camshaft 8 along the cam profile, and the pressure in the pump chamber 12 is not taken into account.
Here, in addition to the acceleration which the plunger 11 receives from the camshaft 8, when the plunger 11 slides in the pump chamber 11, a load by the pressure of the fuel in the pump chamber 12 is applied to the plunger 11. The load is applied to the plunger 11 in a direction opposite to the direction in which the plunger 11 moves in the pump chamber 12, so that the acceleration of the plunger 11 is decreased by the load which the plunger 11 receives from the fuel in the pump chamber 12. In addition to the load which the fuel in the pump chamber 12 applies to the plunger 11, the plunger 11 receives a gravitational acceleration, which is produced by the mass of a movable part of the plunger 11 itself, as a minus acceleration. Hence, when the plunger 11 moves in the pump chamber 12 toward the top dead center, the plunger receives a minus acceleration that is the sum of the acceleration produced by the fuel in the pump chamber 12 and the gravitational acceleration produced by the mass of the movable part of the plunger 11. In other words, while the fuel is compressed in the pump chamber 12, the plunger 11 receives a resultant force of the load to the camshaft 8 side (pressure by the fuel in the pump chamber 12 and the mass of the movable part of the plunger 11) and the biasing force of the first spring 113, so that the plunger 11 is pressed onto the camshaft 8, which hence prevents the plunger 11 from separating from the camshaft 8.
On the other hand, in a case where the plunger 11 does not compress the fuel, the load caused by the pressure of the fuel in the pump chamber 12 becomes small and hence the force of pressing the roller 111 onto the camshaft 8 decreases and hence the minus acceleration that the plunger 11 receives becomes small. In this case, further in a case where the camshaft 8 is rotated at high speeds, since the force of pressing the roller 111 onto the camshaft 8 is small, there is a possibility that the rotation speed of the camshaft 8 will be larger than a speed at which the plunger 11 slides in the pump chamber 12 along the surface of the camshaft 8 and that the roller 111 is temporarily separated from the camshaft 8. Hence, in the present embodiment, by performing a flow shown in Fig. 4, even in a case where the pump discharge instruction is not made, the electromagnetic amount regulation valve 100 is closed to thereby produce the load caused by the pressure of the fuel in the pump chamber 12, which hence prevents the roller 111 from temporarily separating from the camshaft 8.
That is, as shown in time Tb1 to time Tb3 of Fig. 3, even in a state where the signal of the pump discharge instruction does not rise, the ECU 5 turns ON the valve closing signal Sc to the switch circuit 140 (time Tb1) to thereby close the electromagnetic amount regulation valve 100, and after the plunger 11 reaches the top dead center (time Tb2), the ECU 5 turns OFF the valve closing signal Sc to the switch circuit 140 (time Tb3) after a specified time. In this way, even in a case where the high-pressure fuel pump 1 does not need to discharge the fuel to the common rail 3, the ECU 5 closes the electromagnetic amount regulation valve 100 so as to apply the minus acceleration to the plunger 11 to thereby press the plunger 11 onto the camshaft 8.
Hereinafter, the control of the electromagnetic amount regulation valve 100 described above will be described by the use of a control flow shown in Fig. 4. The control flow shown in Fig. 4 is performed by the ECU 5. The control flow is started when specified conditions are satisfied in step 100. In the present embodiment, when one of the specified conditions is satisfied means when the ECU 5 receives a signal of turning on an ignition key for starting an internal combustion engine. That is, when the internal combustion engine is started, the present flow is started, and when the internal combustion engine is stopped, the present flow is finished. Hence, after the internal combustion engine is started, the present flow is normally performed. As the other specified conditions can be thought the following conditions: that is, when the number of revolutions of the camshaft 8 becomes not less than a specified threshold value, the present flow is started; or when the flag of the pump discharge instruction is turned OFF, the present flow is started.
When the present flow is started, in step S100, first, a time variable T is set and the counting of the time variable T is started. Then, the flow proceeds to step S101 where a fuel injection amount to be injected from the injector 4 is calculated on the basis of the signal such as the acceleration opening received by the ECU 5 and where a necessary fuel amount Fm that the high-pressure fuel pump 1 sends under pressure to the common rail 3 on the basis of the calculated fuel injection amount. After the necessary fuel amount Fm is calculated, the flow proceeds to step S102.
In step S102, the number of revolutions R is sensed by the number-of-revolutions sensor 51. The number of revolutions R means the number of revolutions of the camshaft 8 on which the roller 111 abuts. When the number of revolutions R is sensed by the number-of-revolutions sensor 5, the flow proceeds to step 103.
In step 103, it is determined whether or not the necessary fuel amount Fm calculated in step S101 is 0. That the necessary fuel amount Fm to be sent to the common rail 3 from the high-pressure fuel pump 1 is 0 shows that the high-pressure fuel pump 1 does not need to discharge the fuel to the common rail 3, that is, a case where the signal of the pump discharge instruction does not rise. Hence, in a case where the necessary fuel amount Fm is 0, the high-pressure fuel pump 1 does not discharge the fuel to the common rail 3 and hence the electromagnetic amount regulation valve 100 does not seal the inflow port 121. In step S103, in a case where the necessary fuel amount is not 0, it is determined that the fuel is compressed in the pump chamber 12 and the flow returns to step S101. On the other hand, in the case where the necessary fuel amount Fm is 0, it is determined that the fuel is not compressed in the pump chamber 12 and the flow proceeds to step S104.
Next, in step S104, it is determined whether or not the number of revolutions R calculated in step S102 is larger than a number-of-revolutions threshold value Rth. The number-of-revolutions threshold value Rth can be determined by finding the number of revolutions at which the roller 111 starts to separate from the camshaft 8 in a state where the fuel is not compressed by the high-pressure fuel pump 1. Further, it is also recommended to calculate the number-of-revolutions threshold value Rth from various elements such as the mass of the plunger 11, a coefficient of friction between the outer peripheral surface of the camshaft 8 and the roller 111, the viscosity of a lubricant flowing into a gap between the roller 111 and the camshaft 8, and surface temperatures of the camshaft 8 and the roller 111. Here, in the present embodiment, as the number-of-revolutions threshold value Rth, the number of revolutions set previously for the internal combustion engine is used. That is, the number of revolutions set for the purpose of preventing various elements such as a cylinder, a piston, and a throttle, which are provided in the internal combustion engine, from being damaged by high-speed rotation to thereby protect the various elements, in other words, the number of revolutions immediately before the so-called over revolution range is used as the number-of-revolutions threshold value Rth. If it is determined in step S104 that the number of revolutions R is smaller than the number-of-revolutions threshold value Rth, it is determined that the roller 111 is hard to separate from the camshaft 8 and hence the flow returns to step S101. On the other hand, if it is determined in step S104 that the number of revolutions R is not smaller than the number-of-revolutions threshold value Rth, it is determined that the roller 111 is likely to separate from the camshaft 8 and hence the flow proceeds to step S105.
In step S105, the rail pressure Pr is sensed from the first pressure sensor 32. After the rail pressure Pr is sensed, the flow proceeds to step S106.
In step S106, a valve closing start timing Ts and a valve closing end timing Te are calculated. The valve closing start timing Ts is set before a specified time with respect to the top dead center of the cam profile, and the valve closing end timing Ts is set after a specified time with respect to the top dead center of the cam profile. In more detail, a change characteristic and an increasing slant of the pressure of the fuel in the pump chamber 12 when the electromagnetic amount regulation valve 100 is closed is calculated in advance from the characteristic of the fuel flowing into the pump chamber 12, which is estimated in advance, and the volume of the pump chamber 12, which is determined in advance. Then, a pressure Ppn of the fuel in the pump chamber 12 is found from the change characteristic, and the time when the plunger 11 reaches the top dead center is calculated backward from the increasing slant of the pressure of the fuel in the pump chamber 12 in such a way that, at the top dead center of the cam profile, the pressure Ppn of the fuel in the pump chamber 12 does not reach the total value of the specified valve opening pressure Prev of the check valve 13 and the rail pressure Pr sensed in step S105, whereby the valve closing start timing Ts is calculated. Further, a decreasing slant of the pressure of the fuel in the pump chamber 12 when the pressure of the fuel in the pump chamber 12 is decreased from the top dead center of the cam profile is found in advance, and the valve closing end timing Te is calculated on the basis of the decreasing slant. When the valve closing start timing Ts and the valve closing end timing Te are calculated in step S106, the flow proceeds to step S106.
In step S107, it is determined whether or not the time variable T set in step S100 is the valve closing start timing Ts calculated in step S106. In a case where the time variable T is the valve closing start timing Ts, the flow proceeds to step S108. On the other hand, in a case where the time variable T is not the valve closing start timing Ts, step 106 is repeated, that is, it is again determined whether or not the time variable T is the valve closing start timing Ts.
Next, in step S108, the valve closing signal Sc to the switch circuit 140 connected to the electromagnetic amount regulation valve 100 is turned ON. In this way, the armature 101 is attracted by the solenoid 106 and hence the inflow port 121 is sealed by the valve body portion 103 of the armature 101. When the valve closing signal Sc is turned ON in step S108, the flow precedes to the next step S109.
In step S109, it is determined whether or not the time variable T is the valve closing end timing Te calculated in step S105. In a case where the time variable T is not the valve closing end timing Te, step S109 is repeated. On the other hand, in a case where the time variable T is the valve closing end timing Te, the flow proceeds to step 110 where the switch of the switch circuit 140 connected to the electromagnetic amount regulation valve 100 is turned OFF and then the flow proceeds to step S111.
When the flow proceeds to step S111, the present flow again returns to step S100. After returning to step S100, when the condition that the internal combustion engine is stopped is satisfied, the present flow is finished.
Next, the operation and the effect of the present embodiment will be described.
The fuel supply control device of the present embodiment is provided with the number-of-revolutions sensor 51 for sensing the number of revolutions of the camshaft 8, and in a case where the pump discharge instruction of a command for discharging the fuel to the outside from the high-pressure fuel pump 1 does not rise and where the number of revolutions of the camshaft 8 sensed by of the number-of-revolutions sensor 51 is not less than the specified number of revolutions (the number-of-revolutions threshold value Rth), the ECU 5 closes the electromagnetic amount regulation valve 100 in such a way that the plunger 11 compresses the fuel. In other words, even in a case where the fuel does not need to be discharged to the outside, in a case where the number of revolutions of the camshaft 8 is not less than the specified number of revolutions Rth, the ECU 5 determines that the plunger 11 is highly likely to separate from the camshaft 8 and sends the valve closing signal to the electromagnetic amount regulation valve 100 to thereby make the plunger 11 compress the fuel. In this way, the compressed fuel presses the plunger 11 to the camshaft 8 side, whereby a state where the plunger 11 abuts on the camshaft 8 is held. Hence, in the case where the pump discharge instruction for discharging the fuel to the outside does not rise, that is, even in the case where the fuel does not need to be discharged to the outside, the state where the plunger 11 abuts on the camshaft 8 can be held. In this way, it is possible to provide the fuel supply control device that can prevent the plunger 11 from separating from the camshaft 8 and that has a high degree of silence.
Further, the fuel supply control device of the present embodiment is provided with: the common rail 3, which communicates with the discharge port 15 and which holds the high-pressure fuel discharged from the discharge port 15; and the first pressure sensor 32, which is provided in the common rail 3 and which senses the rail pressure Pr of the pressure of the fuel in the common rail 3. The ECU 5 closes the electromagnetic amount regulation valve 100 in such a way that the fuel is not discharged to the common rail 3 on the basis of the specified valve opening pressure Prev of the check valve 13 and the rail pressure Pr sensed by the first pressure sensor 32.
According to this, the fuel, which is not discharged to the common rail 3 but is compressed, presses the plunger 11 to the camshaft 18 side, whereby the state where the plunger 11 abuts on the camshaft 8 can be held. Hence, it is possible to provide the fuel supply control device that can hold the state where the plunger 11 abuts on the camshaft 8 and that has a high degree of silence.
Still further, in the fuel supply control device of the present embodiment, the ECU 5 calculates the pressure Ppn when the fuel is compressed by the plunger 11 on the basis of the predetermined volume of the pump chamber 12 and closes the electromagnetic amount regulation valve 100 in such a way that the calculated pressure Ppn in the pump chamber 12 is smaller than the total value of the predetermined valve opening pressure Prev of the check valve 13 and the rail pressure Pr sensed by the first pressure sensor 32. According to this, the ECU 5 calculates the pressure Ppn in the pump chamber 12 on the basis of the volume of the pump chamber 12, so even if the plunger 11 slides in the pump chamber 12 to change the volume of the pump chamber 12, the ECU 5 can close the electromagnetic amount regulation valve 100 in such a way that the check valve 13 is not opened by the pressure Ppn in the pump chamber 12. Hence, the fuel, which is not discharged to the outside but is compressed, presses the plunger 11 to the camshaft 8 side to whereby the state in which the plunger 11 abuts on the camshaft 8 can be held. Hence, it is possible to provide the fuel supply control device that can hold the state where the plunger 11 abuts on the camshaft 8 and that has a high degree of silence.
Still further, in the present embodiment, the number-of-revolutions threshold value Rth is the number of revolutions set previously for the internal combustion engine and is set on the basis of the number of revolutions that protects various elements provided in the internal combustion engine. According to this, by the use of the number of revolutions, it is possible to determine whether or not the number of revolutions R of the camshaft 8, which is brought into a high rotation range, is the number of revolutions at which the plunger 11 will be highly likely to separate from the camshaft 8. When the number of revolutions R of the camshaft 8 is not less than the number-of-revolutions threshold value Rth, the electromagnetic amount regulation valve 100 is closed, whereby the plunger 11 can be prevented from separating from the camshaft 8. Hence, it is possible to provide the fuel supply control device that can hold the state where the plunger 11 abuts on the camshaft 8 and that has a high degree of silence.

(Second Embodiment)

A second embodiment will be described by the use of Fig. 5 and Fig. 6. The high-pressure fuel pump 1 of the second embodiment, as shown in Fig. 5, has a second pressure sensor 16 provided in the second passage 15 between the discharge port 122 and the check valve 13. The second pressure sensor 16 is connected to the ECU 5 and senses the pressure in the pump chamber 12 (hereinafter referred to as a pump chamber pressure Ppo) and sends the sensed pump chamber pressure Ppo to the ECU 5.
A flow of the present embodiment will be shown in Fig. 6. The flow of the present embodiment is started when the same specified conditions as in the first embodiment are satisfied. On the other hand, in step 200, the counting of the time variable T is not started. Here, steps S201 to S204 are the same as steps 101 to S104 in the first embodiment, so that their descriptions will be omitted.
When it is determined in step S204 that the number of revolutions R of the camshaft 8 is not less than the number-of-revolutions threshold value Rth, the flow proceeds to step 205 where the valve closing signal Sc is sent to the switch circuit 140 connected to the electromagnetic amount regulation valve 100 and the switch is turned ON. In this way, the armature 101 is attracted by the solenoid 106, whereby the inflow port 121 is sealed by the valve body portion 103 of the armature 101. When the valve closing signal is turned ON in step S205, the flow proceeds to the next step S206.
In step S206, the rail pressure Pr is acquired from the first pressure sensor 32 provided in the common rail 3. When the rail pressure Pr is sensed, the flow proceeds to step S207 where a pump chamber pressure Ppo is acquired from the second pressure sensor 16. After the pump chamber pressure Ppo is acquired, the flow proceeds to step S208.
In step S208, it is determined whether or not the pump chamber pressure Ppo is larger than the sum of the rail pressure Pr and the valve opening pressure Prev of the check valve 13 (that is, the biasing force of the fourth spring 132). In a case where the pump chamber pressure Ppo is smaller than the sum of the rail pressure Pr and the valve opening pressure Prev of the check valve 13, the check valve 13 is not opened and hence the fuel is not discharged to the common rail 3. On the other hand, in a case where the pump chamber pressure Ppo is larger than the sum of the rail pressure Pr and the valve opening pressure Prev of the check valve 13, the check valve 13 is opened and hence the flow proceeds to step S209 where the valve closing signal Sc is turned OFF. In this way, the switch of the switch circuit 140 connected to the electromagnetic amount regulation valve 100 is turned OFF, whereby the passing of the current through the electromagnetic amount regulation valve 100 is stopped. When the switch of the switch circuit 140 is turned OFF and then the flow proceeds to step S210, the present flow is again returned to step S200. When the flow returns to step S200 and then the condition such that the internal combustion engine is stopped is satisfied, the present flow is finished.
Next, the effects of the present embodiment will be described.
The fuel supply control device of the present embodiment is provided with: the common rail 3, which communicates with the discharge port 122 and which holds the high pressure fuel discharged from the discharge port 122; the first pressure sensor 32, which is provided in the common rail 3 and which senses the rail pressure Pr of the pressure in the common rail 3; and the second pressure sensor 16, which is interposed between the discharge port 122 of the pump chamber 12 and the check valve 13 and which senses the pump chamber pressure Ppo. The ECU 5 closes the electromagnetic amount regulation valve 100 in such a way that the pressure of the pump chamber 12 is smaller than the total value of the specified valve opening pressure Prev of the check valve 13 and the rail pressure Pr sensed by the first pressure sensor 32 on the basis of the specified valve opening pressure Prev of the check valve 13 provided in the discharge port 122, the rail pressure Pr sensed by the pressure sensor 51, and the pump chamber pressure Ppo sensed by the second pressure sensor 16. In this way, the electromagnetic amount regulation valve 100 is closed in response to the pump chamber pressure Pp, which is normally changed, and the rail pressure Pr, whereby the fuel can be compressed in the pump chamber 12 without opening the check valve 13 to send the fuel under pressure to the common rail 3. Hence, it is possible to provide the fuel supply control device that can hold the state where the plunger 11 abuts on the camshaft 8 without changing the fuel injection amount and that has a high degree of silence.

(Third Embodiment)

A third embodiment can employ the construction of the fuel supply control device shown in the first embodiment and the second embodiment. On the other hand, the third embodiment is different from the first embodiment and the second embodiment in a control flow performed by the ECU 5. The control flow of the present embodiment will be described by the use of Fig. 7.
In the present embodiment, in step S300, first, the time variable T is set and the counting of the time variable T is started. Then, the flow proceeds to step S301 where a fuel injection amount to be injected by the injector 4 is calculated on the basis of the accelerator opening received by the ECU 5 and where the necessary fuel amount Fm to be sent under pressure to the common rail 3 by the high-pressure fuel pump 1 is calculated on the basis of the calculated fuel injection amount. Further, an injection pressure required when the injector 4 injects the fuel is calculated as a pressure threshold value Prth. After the necessary fuel amount Fm is calculated, the flow proceeds to step S302. Steps S302 to S304 are the same as steps 102 to S104 in the first embodiment, so their descriptions will be omitted.
If it is determined in step S304 that the number of revolutions R of the camshaft 8 is not less than the pressure threshold value Prth, the flow proceeds to step S305 where: as is the case with the steps S105 and S106 in the first embodiment, the rail pressure Pr is sensed by the first pressure sensor 32; and the valve closing start timing Ts and the valve closing end timing Te are calculated.
After the valve closing start timing Ts and the valve closing end timing Te are calculated in step S305, the flow proceeds to step S306 where it is determined whether or not the time variable T is not less than the valve closing start timing Ts. In a case where the time variable T is not less than the valve closing start timing Ts, the flow proceeds to step S307 where the valve closing signal Sc is sent to the electromagnetic amount regulation valve 100. On the other hand, in a case where the time variable T does not reach the valve closing start timing Ts, step S306 is again performed, whereby it is determined whether or not the time variable T is not less than the valve closing start timing Ts.
When the time T is more than the valve closing start timing Ts and the valve closing signal Sc is sent to the electromagnetic amount regulation valve 100 in step S307, next, the flow proceeds to step S308 where it is determined whether or not the time variable T is not less than the valve closing end timing Te. If it is determined in step S308 that the time variable T does not reach the valve closing end timing Te, the flow proceeds to step S309.
In step S309, the rail pressure Pr is again sensed by the first pressure sensor 32. Then, the flow proceeds to step S310 where it is determined whether or not the rail pressure Pr is larger than the pressure threshold value Prth calculated in step S301. In a case where the rail pressure Pr is larger than the pressure threshold value Prth, it is determined that the pressure in the common rail 3 is higher than a desired pressure and the flow proceeds to step S311.
In step S311, a valve opening signal Sr is sent to the regulation valve 31. In this way, the fuel is returned to the fuel tank 6 from the regulation valve 31 via the leak passage 73, whereby the rail pressure Pr is decreased. On the other hand, in a case where the rail pressure Pr is smaller than the pressure threshold value Prth, the flow returns to step S308 where it is determined whether or not the time variable T is not less than the valve closing end timing Te.
On the other hand, after the regulation valve 31 is opened in step S311, the flow proceeds to step S312. In step S312, it is again determined whether or not the rail pressure Pr is larger than the pressure threshold value Prth. Here, in a case where the rail pressure Pr is smaller than the pressure threshold value Prth, it is determined that the rail pressure Pr does not need to be more decreased by the regulation valve 31 and the flow proceeds to step S313 where the valve opening signal Sr to the regulation valve 31 is turned OFF to thereby stop opening the regulation valve 31. In this way, even if the fuel is discharged from the high-pressure fuel pump 1, the rail pressure Pr of the common rail 3 can be stabilized at a specified pressure. On the other hand, in a case where it is determined in step S312 that the rail pressure Pr is larger than the pressure threshold value Prth, step S312 is again performed, whereby it is determined whether or not the rail pressure Pr is not less than the pressure threshold value Prth.
In a case where it is determined in step S308 that the time variable T is not less than the valve closing end timing Te, the flow proceeds to step S314 where the valve closing signal Sc is turned OFF. Then, the switch of the switch circuit 140 connected to the electromagnetic amount regulation valve 100 is turned OFF, whereby the electromagnetic amount regulation valve 100 is opened. Then, when the electromagnetic amount regulation valve 100 is opened, the flow proceeds to step S315 and the present flow is again returned to step S300. After the flow returns to step S300, when a specified condition such that the internal combustion engine is stopped is satisfied, the present flow is finished.
Next, the operation and effect of the present embodiment will be described.
The fuel supply control device of the present embodiment is provided with: the common rail 3, which communicates with the discharge port 122 and which holds the high pressure fuel discharged from the discharge port 122; the first pressure sensor 32 for sensing the rail pressure Pr; and the regulation valve 31 for returning the fuel in the common rail to the fuel tank 6. Further, the ECU 5 opens the regulation valve 31 in such a way that the rail pressure Pr, which is increased when the electromagnetic amount regulation valve 100 is closed to thereby discharge the fuel to the common rail, is held at the pressure threshold value Prth. In other words, when the rail pressure Pr of the pressure in the common rail 3 is larger than the pressure threshold value Prth of the specified pressure, the regulation valve 31 is opened, whereas when the rail pressure Pr of the pressure in the common rail 3 is smaller than the pressure threshold value Prth, the regulation valve 31 is not opened.
In this way, even if the fuel is discharged to the common rail 3 from the high-pressure fuel pump 1, by returning the fuel to the fuel tank 6 from the regulation valve 31, the rail pressure Pr in the common rail 3 can be held at a specified value. Hence, it is possible to prevent the pressure in the common rail 3 from changing to thereby vary the amount of the fuel to be supplied to the injector 4 and at the same time to prevent the roller 111 of the plunger 11 from separating from the camshaft 8. Hence, it is possible to provide the fuel supply control device that can hold the state where the plunger 11 abuts on the camshaft 8 and that has a high degree of silence.

(Fourth Embodiment)

In a fourth embodiment, in the first embodiment, the electromagnetic amount regulation valve 100 is closed in such a way that the pressure of the fuel discharged from the high-pressure fuel pump 1 does not become more than the pressure threshold value Prth, thereby discharging the fuel to the common rail 3. That is, in the first embodiment, the electromagnetic amount regulation valve 100 is closed in such a way as not to discharge the fuel to the common rail 3. In contrast to this, in the present embodiment, a part of the fuel is discharged to the common rail 3 in such a way that the rail pressure Pr does not become more than the pressure threshold value Prth. Specifically, in the flow of the first embodiment shown in Fig. 4, when the necessary fuel amount is calculated in the first step S101, as is the case with step S301 of the third embodiment, the pressure threshold value Prth is calculated. Then, when the valve closing start timing Ts and the valve closing end timing Te are calculated in step S106, the valve closing start timing Ts and the valve closing end timing Te are calculated in such a way that the pressure Ppn in the pump chamber 12 is larger than the total value of the specified valve opening pressure Prev at which the check valve 13 is opened and the rail pressure Pr and that the rail pressure Pr is not larger than the pressure threshold value Prth.
By setting the valve closing start timing Ts and the valve closing end timing Te in this way, the fuel is allowed to be discharged from the high-pressure fuel pump 1, whereas the rail pressure Pr is made not larger than the pressure threshold value Prth.
Hence, even if the fuel is discharged to the common rail 3 from the high-pressure fuel pump 1, while the pressure of the fuel discharged from the injector 4 can be prevented from becoming more than a necessary pressure, the roller 111 of the plunger 11 can be prevented from separating from the camshaft 8. Hence, it is possible to provide the fuel supply control device that holds the state where the plunger 11 abuts on the camshaft 8 and that has a high degree of silence.

(Other Embodiments)

Up to this point, the respective embodiments of the present invention have been described. However, the present invention is not limited to the embodiments described above but can be applied to various embodiments within a scope not departing from the gist of the present invention.

Claims

A fuel supply control device including: a pump chamber (12) having an inflow port (14) through which fuel flows in and a discharge port (15) for discharging the fuel to the outside; a first electromagnetic valve (10) which is provided in the inflow port for closing the inflow port; a check valve (10) which is provided in the discharge port and which is opened when a pressure of the fuel in the pump chamber becomes not less than a specified valve opening pressure (Prev); a control means (5) for closing the first electromagnetic valve; a camshaft (8) which receives power from an internal combustion engine; and a plunger (11) which slides in the pump chamber,
wherein the first electromagnetic valve closes the inflow port and the plunger is slid in the pump chamber to thereby compress the fuel flowing into the pump chamber, thereby discharging the fuel to the outside,
the fuel supply control device comprising:
a number-of-revolutions sensing means (51) for sensing a number of revolutions (R) of the camshaft,

wherein in a case where a discharge instruction signal that is a command of discharging the fuel is not turned on and where the number of revolutions (R) sensed by the number-of-revolutions sensing means is not less than a specified number of revolutions (Rth), the control means closes the first electromagnetic valve in such a way that the plunger compresses the fuel.
A fuel supply control device according to claim 1, further comprising:
a common rail (3) which communicates with the discharge port and which holds the high pressure fuel discharged from the discharge port; and

a first pressure sensor (32) which is provided in the common rail and which senses a rail pressure (Pr) that is a pressure of the fuel in the common rail,

wherein the control means closes the first electromagnetic valve in such a way that the fuel is not discharged to the common rail on the basis of the specified valve opening pressure (Prev) of the check valve and the rail pressure (Pr) sensed by the first pressure sensor.
A fuel supply control device according to claim 2,
wherein the control means calculates a pressure value (Ppn) when the fuel is compressed by the plunger on the basis of a predetermined volume of the pump chamber, and
wherein the control means closes the first electromagnetic valve in such a way that the calculated pressure (Ppn) in the pump chamber is smaller than a total value of the specified valve opening pressure (Prev) of the check valve and the rail pressure (Pr) sensed by the first pressure sensor.
A fuel supply control device according to claim 2, further comprising:
a second pressure sensor (16) which is interposed between the discharge port and the common rail and which senses a pressure in the pump chamber,

wherein, on the basis of the pressure (Ppo) in the pump chamber which is sensed by the second pressure sensor, the specified valve opening pressure (Prev) of the check valve, and the rail pressure (Pr) sensed by the first pressure sensor, the control means closes the first electromagnetic valve in such a way that the pressure (Ppo) in the pump chamber is smaller than a total value of the specified valve opening pressure (Prev) of the check valve and the rail pressure (Pr) sensed by the first pressure sensor.
A fuel supply control device according to claim 1, further comprising:
a common rail (3) which communicates with the discharge port and which holds the high pressure fuel discharged from the discharge port; and

a first pressure sensor (32) which is provided in the common rail and which senses a rail pressure (Pr) that is a pressure of the fuel in the common rail,

wherein, on the basis of the rail pressure (Pr) sensed by the first pressure sensor, the control means closes the first electromagnetic valve in such a way that the rail pressure (Pr) is not made larger than the specified pressure (Prth) by the fuel discharged to the common rail.
A fuel supply control device according to claim 1, further comprising:
a common rail (3) which communicates with the discharge port and which holds the high pressure fuel discharged from the discharge port;

a first pressure sensor (32) which is provided in the common rail and which senses a rail pressure (Pr) that is a pressure of the fuel in the common rail; and

a second electromagnetic valve (31) which is provided in the common rail and which discharges the fuel held in the common rail to the outside,

wherein the control means opens the second electromagnetic valve in such a way that the rail pressure (Pr), which is increased when the first electromagnetic valve is closed and the fuel is discharged to the common rail, is held at a specified pressure (Prth).
A fuel supply control device according to any one of claims 1 to 6,
wherein the specified number of revolutions (Rth) is a number of revolutions which is previously set for the internal combustion engine and which is calculated on the basis of a number of revolutions for protecting various elements provided in the internal combustion engine.