JP2009162180A - Fuel supply device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure capacities of fuel pumps as a whole, and to secure a drive torque reduction margin by selectively operating the fuel pumps in a fuel supply device for an engine provided with a plurality of the fuel pumps driven by the engine. <P>SOLUTION: This device is provided with a first fuel pump 3 driven by the engine and having a relatively small capacity and a second fuel pump 4 driven by the engine and having a capacity larger than that of the first fuel pump 3 as the fuel pumps for supplying the engine with fuel stored in the fuel tank 1. The fuel pumps 3, 4 are selectively operated according to engine operation conditions. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel supply device for an engine, and more specifically, includes a plurality of pumps driven by an engine as pumps for fuel supply, and switches these fuel pumps according to operating conditions of the engine and operates them. The present invention relates to a technique for reducing driving torque of a fuel pump and reducing fuel consumption of an engine.

  2. Description of the Related Art As a pump for supplying fuel stored in a fuel tank to an engine (hereinafter referred to as “fuel pump”), the following fuel supply device having a plurality of fuel pumps in a fuel supply pipe is known. .

  First, as a fuel pump, an electric pump having a constant capacity and an electric pump having a variable capacity, and the former fixed-capacity type fuel pump at the time of small amount injection with a small fuel injection amount While the variable displacement type fuel pump is operated to supply fuel (Patent Document 1).

Second, as fuel pumps, two fuel pumps of equal capacity driven by an engine are provided (Patent Document 2).
JP 05-157003 A (paragraph numbers 0011, 0013) JP 2006-336593 A (paragraph number 0010)

However, in the first fuel supply device, the fuel pump provided in the first fuel supply device is an electric type and is not driven by the engine.
The second fuel supply device has the following problems.

  According to this, the fuel injection valve (common rail) is supplied with fuel by a plurality of fuel pumps driven by the engine, so that the capacity of the fuel pump as a whole is ensured, and the common rail in the common rail is started when the engine is started. Since the fuel can be quickly boosted, the engine startability can be improved. However, this second fuel supply device does not operate by switching a plurality of fuel pumps. Also, even if one fuel pump is stopped and fuel is supplied only by the other fuel pump, the capacity of each fuel pump is equal, so the driving torque reduction by stopping one fuel pump is small, and the engine The fuel consumption cannot be reduced satisfactorily.

  In consideration of the above-described problems, the present invention secures the capacity of the entire fuel pump in an engine fuel supply apparatus including a plurality of fuel pumps driven by the engine, and these fuels according to engine operating conditions. An object is to secure a sufficient drive torque reduction margin by selectively operating the pump and to reduce the fuel consumption of the engine.

  The present invention provides an engine fuel supply apparatus. In the present invention, a fuel tank for storing fuel supplied to the engine is provided, and a fuel pump for supplying the fuel stored in the fuel tank to the engine is relatively driven by the engine. A first fuel pump having a small capacity and a second fuel pump having a larger capacity than the first fuel pump driven by the engine are provided, and these fuel pumps are selectively selected by a command signal from the control unit. It is to be operated.

  According to the present invention, since a plurality of fuel pumps (first and second fuel pumps) having different capacities are provided and these fuel pumps are selectively operated, the first and second fuel pumps By operating both, the capacity of the fuel pump as a whole can be ensured. Further, by stopping the second fuel pump having a large capacity, the driving torque of the fuel pump can be significantly reduced, and the fuel consumption of the engine can be reduced.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows the configuration of an engine fuel supply apparatus according to a first embodiment of the present invention. The fuel supply device according to the present embodiment is provided in a direct injection engine in which fuel is directly injected into a cylinder.

  The fuel supplied to the engine is stored in the fuel storage section of the fuel tank module 1, sent to the low-pressure fuel pipe 2 by the low-pressure feed pump 101, and further pressurized by the high-pressure fuel pump to be described later. Supplied to the injection valve. The low-pressure feed pump 101 is an electric fuel pump, and is driven by an electric motor 102 that uses a battery (not shown) as a power source. The filters 103 and 104 are for removing foreign matters mixed in the fuel, and are provided at appropriate locations in the fuel tank module 1. The pressure regulating valve 105 is for regulating the pressure of the fuel in the low-pressure fuel pipe 2 by returning surplus fuel exceeding a predetermined pressure to the fuel storage unit. The fuel storage unit of the fuel tank module 1 corresponds to a “fuel tank”. The low-pressure fuel pipe 2 and the next high-pressure fuel pipe 5 constitute a “fuel supply pipe” of this engine.

  The fuel sent out by the feed pump 101 is further pressurized by the high-pressure fuel pumps 3 and 4 and sent out to the high-pressure fuel pipe 5 (shown by a thick line in FIG. 1). In the present embodiment, two fuel pumps 3 and 4 having different capacities are provided as the high-pressure fuel pump. These fuel pumps 3 and 4 are both variable displacement fuel pumps and are driven by the engine. Is done. The first fuel pump 3 is set to a relatively small maximum discharge amount, while the second fuel pump 4 is set to a maximum discharge amount larger than that of the first fuel pump 3.

  In the first fuel pump 3, a pressurizing cylinder 301a is interposed between the low pressure fuel pipe 2 and the high pressure fuel pipe 5, and a plunger 302a is inserted into the pressurizing cylinder 301a so as to reciprocate up and down. Has been. The plunger 302a is driven by a first cam 303a connected to an engine camshaft (not shown). In the present embodiment, the first cam 303a has a relatively low nose portion, and imparts a first lift amount to the plunger 302a. As the first cam 303a rotates, the plunger 302a moves downward to expand the pressurizing chamber R1 defined by the pressurizing cylinder 301a and the plunger 302a. Inhaled fuel. The sucked fuel is compressed by the plunger 302 a changing its direction and moving upward to reduce the pressurizing chamber R <b> 1, and is sent out to the high-pressure fuel pipe 5. The electromagnetic control valve 304 is for controlling the discharge amount of the first fuel pump 3, and its duty ratio is controlled based on a command signal from an engine control unit described later. The electromagnetic control valve 304 also functions as a “flow path shutoff valve” when the first fuel pump 3 is stopped. The check valves 305 and 306 are for allowing the flow of fuel from the low pressure fuel pipe 2 to the high pressure fuel pipe 5 and preventing the reverse flow, and are provided on the inlet side and the outlet side of the pressurizing cylinder 301a, respectively. It has been. The safety valve 307 is for avoiding an excessive increase in pressure in the high pressure fuel pipe 5 by returning surplus fuel to the low pressure fuel pipe 2 when the fuel in the high pressure fuel pipe 5 exceeds a predetermined pressure. It is. The pressure attenuator 308 is for suppressing fuel pressure pulsation in the low-pressure fuel pipe 2. In the first fuel pump 3, a filter 309 is provided at an appropriate location.

  On the other hand, the second fuel pump 4 is different from the first fuel pump 3 only in the height of a nose portion provided in a cam (corresponding to a “second cam”) 403a for driving the plunger 402a. The other components are the same as those in the first fuel pump 3. That is, the pressurizing cylinder 401a is interposed between the low-pressure fuel pipe 2 and the high-pressure fuel pipe 5, and the pressurizing chamber of the second fuel pump 4 is interposed between the plunger 402a that is movably inserted up and down. R2 is formed. The second cam 403a is connected to the camshaft of the engine. As the plunger 402a moves up and down, the pressurizing chamber R2 expands and contracts, and the compressed fuel is sent out to the high-pressure fuel pipe 5. . In the present embodiment, the nose portion of the second cam 403a is formed higher than that of the first cam 303a, and the second lift amount larger than that in the first fuel pump 3 is larger than the plunger 402a. Is granted. In this embodiment, a branch pipe for circulating the fuel sent out by the first fuel pump 3 and a branch pipe for circulating the fuel sent out by the second fuel pump 4 are provided. The fuel sent out by the first and second fuel pumps 3 and 4 joins at the collecting portion of these branch pipes and is then supplied to the fuel injection valve. The electromagnetic control valve 404 is for controlling the discharge amount of the second fuel pump 4, and also functions as a “flow-path cutoff valve”. The check valves 405 and 406 are for preventing a back flow of fuel from the high pressure fuel pipe 5 to the low pressure fuel pipe 2, and the safety valve 407 avoids an excessive increase in pressure in the high pressure fuel pipe 5. Is for. The pressure attenuator 408 for suppressing the pressure pulsation of the fuel in the low pressure fuel pipe 2 and an appropriate filter 409 are provided as in the first fuel pump 3.

  The fuel sent out by the first and second fuel pumps 3 and 4 is supplied to the fuel injection valves 6 a to 6 f provided in each cylinder via the high-pressure fuel pipe 5. The fuel injection valves 6a to 6f are installed with their injection holes facing the cylinder of the engine, and directly inject fuel into the cylinder. In the present embodiment, a common rail 7 is connected to the high-pressure fuel pipe 5, and fuel is supplied from the common rail 7 to the fuel injection valves 6a to 6f. The orifice 8 is for reducing the pressure pulsation of the fuel sent out by the first and second fuel pumps 3 and 4 and suppressing the pressure fluctuation in the common rail 7. It is installed downstream of the gathering part.

  The operations of the first and second fuel pumps 3 and 4, the feed pump 101, and the fuel injection valves 6 a to 6 f are engine control units (hereinafter referred to as “ECUs”) 501 configured as electronic control units including a microcomputer. Is controlled by a command signal from The ECU 501 outputs a signal from the accelerator sensor 551 for detecting the amount of operation of the accelerator pedal by the driver (hereinafter referred to as “accelerator operation amount”) and a crank angle sensor 552 as a signal indicating the operating condition of the engine. A signal for each unit crank angle and reference crank angle, a signal from the coolant temperature sensor 553 for detecting the temperature of the engine coolant, and a temperature of fuel pressurized by the high-pressure fuel pumps 3 and 4 A signal from the fuel temperature sensor 554, a signal from the fuel pressure sensor 555 for detecting the pressure of the fuel injected by the fuel injection valves 6a to 6f, and the like are input, and the first and first signals are input based on these detection signals. 2 controls the operation of the fuel pumps 3, 4 and the like. In the present embodiment, the fuel temperature sensor 554 is installed in the fuel tank module 1 and detects the temperature of the fuel stored in the fuel storage unit. The fuel pressure sensor 555 is installed on the common rail 7 and detects the pressure of the fuel in the common rail 7. The ECU 501 feedback-controls the discharge amounts of the first and second fuel pumps 3 and 4 based on the fuel pressure detected by the fuel pressure sensor 555, and adjusts it to a predetermined target pressure according to the engine operating conditions. .

Next, operations related to fuel supply control of the ECU 501 will be described with reference to flowcharts.
FIG. 2 is a flowchart of a fuel supply control routine according to the present embodiment.

In S101, the accelerator operation amount APO detected by the accelerator sensor 551 is read as an operating condition parameter indicating the engine load.
In S102, based on the accelerator operation amount APO, it is determined whether or not the engine operating condition is in a region other than the low load region. If the accelerator operation amount APO is equal to or greater than the predetermined operation amount APO1 set with a relatively small value and the engine operating condition is in a region other than the low load region, the process proceeds to S103, and the low load region is reached. If there is, the process proceeds to S104.

  In S103, based on the accelerator operation amount APO, it is determined whether or not the engine operating condition is in a region other than the low load region and the medium load region. The accelerator operation amount APO is equal to or greater than a predetermined operation amount APO2 set with a larger value than APO1, and the engine operating condition is in a region other than the low load region and the medium load region (ie, high load region). If so, the process proceeds to S106, and if it is in the middle load range, the process proceeds to S105.

  In S104, the second fuel pump 4 of the first and second fuel pumps 3 and 4 is stopped, the first fuel pump 3 (small lift amount pump having a small nose portion of the cam and a small maximum discharge amount). ) Only to supply fuel. The second fuel pump 4 is stopped by shutting off the flow of fuel through the fuel pump 4 by the electromagnetic control valve 404.

  In S105, the first fuel pump 3 of the first and second fuel pumps 3 and 4 is stopped, the second fuel pump 4 (large lift amount pump having a large nose portion of the cam and a large maximum discharge amount). ) Only to supply fuel. The first fuel pump 3 is stopped by shutting off the fuel flow through the fuel pump 3 by means of the electromagnetic control valve 304.

In S106, both the first and second fuel pumps 3 and 4 are operated, and fuel is supplied from these fuel pumps 3 and 4.
In S107, the discharge amounts of the first fuel pump 3 and the second fuel pump 4 are controlled. In the present embodiment, as the discharge amount control, control is performed for making the fuel discharge amounts from the fuel pumps 3 and 4 coincide according to the flowchart shown in FIG.

FIG. 3 is a flowchart showing the contents of the discharge amount control (S107 in the flowchart of FIG. 2).
In S107a, the discharge rates η1 and η2 of the first and second fuel pumps 3 and 4 are set. The discharge rates η1 and η2 indicate the ratio of the actual discharge amount to the maximum discharge amount of the fuel pump. The discharge rate of 50% means that the fuel pump is operated with a discharge amount that is half the maximum discharge amount. Indicates that In the present embodiment, the discharge rates η1 and η2 at which the discharge amounts of the first and second fuel pumps 3 and 4 are equal are set. Therefore, when both the first and second fuel pumps 3 and 4 are operated, the discharge rate η1 of the first fuel pump 3 having a small maximum discharge amount is the second fuel pump 4 having a large maximum discharge amount. Is set to a value larger than the discharge rate η2.

In S107b, the fuel temperature TF detected by the fuel temperature sensor 554 is read.
In S107c, it is determined whether or not the temperature TF of the read fuel is equal to or higher than a predetermined temperature TF1. The predetermined temperature TF1 corresponds to the upper limit of the effective operating temperature corresponding to the discharge rate η1 of the first fuel pump 3. The fact that the fuel temperature TF is equal to or higher than the predetermined temperature TF1 means that the first fuel pump 3 has reached a substantial upper limit discharge rate ηmax, and the amount corresponding to the discharge rate η1 for which the actual discharge amount has been set. Indicates not satisfied. When the fuel temperature TF is equal to or higher than the predetermined temperature TF1, the process proceeds to S107d. When the fuel temperature TF is lower than TF1, this routine is terminated.

In S107d, the discharge rate η2 of the second fuel pump 4 is corrected and the discharge amount is decreased so as to match the discharge amount actually obtained by the first fuel pump 3.
According to this embodiment, the following effects can be obtained.

  In the present embodiment, a plurality of fuel pumps (first and second fuel pumps) 3 and 4 having different nose portions of the cam are provided, and these fuel pumps 3 and 4 are used as engine operating conditions. It was decided to operate selectively according to the response. That is, when the engine operating condition is in a low load range, the first fuel pump 3 having a low cam nose and a small capacity is operated, and fuel is supplied only by the first fuel pump 3. The engine torque required for driving the fuel pump 3 can be reduced, and the fuel consumption of the engine can be reduced. On the other hand, when the operating condition of the engine is in the high load range, in addition to the first fuel pump 3, the second fuel pump 4 having a high cam nose and large capacity is operated, and these fuel pumps 3, By supplying the fuel with both of the fuel pumps 4 and 4, the capacity of the fuel pumps 3 and 4 as a whole can be secured, and the fuel injection amount required during high-load operation can be secured. Further, when the engine operating condition is in the middle load range between the low load range and the high load range, the fuel is supplied only by the second fuel pump 4 to reduce the fuel consumption of the engine. The necessary fuel injection amount can be ensured.

  In the present embodiment, when fuel is supplied from both the first and second fuel pumps 3 and 4, the discharge rates η1 and η2 of these fuel pumps 3 and 4 are individually controlled, and the first Since the discharge amount of the fuel pump 3 and the discharge amount of the second fuel pump 4 are made to coincide with each other, the pressure pulsation in the common rail 7 can be reduced and the fuel injection amount can be accurately controlled.

  FIG. 4 shows a case where the pressure PF of the fuel in the common rail 7 is set so that the discharge amounts of the first and second fuel pumps 3 and 4 match (A) and the discharge rates η1 and η2 match (B ) Is schematically shown. 4A and 4B, the discharge pressure P1 from the first fuel pump 3 is indicated by a dotted line, and the discharge pressure P2 from the second fuel pump 4 is indicated by a one-dot chain line. In addition, the period shown by Ti1-Ti6 has shown the injection period by the fuel injection valves 6a-6f installed in each cylinder.

  In the present embodiment, as shown in FIG. 4 (A), the discharge amounts P1 of the fuel between the fuel pumps 3 and 4 are matched by matching the discharge amounts of the first and second fuel pumps 3 and 4. , P2 can be suppressed, and pressure pulsation in the common rail 7 can be suppressed. For this reason, it is possible to reduce the volume of the fuel supply system downstream of the fuel pumps 3 and 4, and quickly increase the fuel pressure in the common rail 7 at the start of the engine to achieve quick start. Can be made.

  On the other hand, when the discharge rates η1 and η2 of the first and second fuel pumps 3 and 4 are matched as shown in FIG. Therefore, the actual discharge amount, and hence the discharge pressures P1 and P2, are shifted, and the pressure pulsation Ppul in the common rail 7 is deteriorated. For this reason, fluctuations occur in the fuel pressure PF, making it difficult to accurately control the fuel injection amount.

  Further, in the present embodiment, when both the first and second fuel pumps 3 and 4 are operated and the fuel pumps 3 and 4 are controlled using the discharge rates η1 and η2 as variables, the fuel tank module 1 The temperature TF of the stored fuel is detected, and the discharge rate η2 of the second fuel pump 4 is corrected based on the detected temperature TF. As a result, even when the fuel temperature TF rises during high-load operation and the discharge amount corresponding to the discharge rate η1 set by the first fuel pump 3 cannot be obtained, the first and second The discharge amounts of the fuel pumps 3 and 4 can be matched to avoid the deterioration of pressure pulsation.

  Hereinafter, other embodiments of the present invention will be described. In the following description, differences from the fuel supply apparatus according to the first embodiment will be mainly described, and detailed descriptions of other common points will be omitted.

FIG. 5 shows a configuration of a fuel supply device for a direct injection engine according to the second embodiment of the present invention.
In the present embodiment, the first fuel pump 3 having a small capacity is relatively replaced with the pressurizing cylinders 301a and 401a, the plungers 302a and 402a, and the cams 303a and 403a of the fuel supply device according to the first embodiment. The second plunger 402b having a larger diameter than the first plunger 302b is provided for the second fuel pump 4 in which the first plunger 302b having a small diameter has a large capacity. The pressurizing cylinders 301b and 401b of the fuel pumps 3 and 4 are adapted to the inner diameters according to changes in the diameters of the plungers 302b and 402b. Cams 303b and 403b for driving these plungers 302b and 402b each have a nose portion having an equal height. The pressure cylinders 301b and 401b, the first and second plungers 302b and 402b, the elements of the fuel pumps 3 and 4 other than the cams 303b and 403b, the fuel tank module 1, the fuel injection valves 6a to 6f, the common rail 7 and the engine The control unit 501 and the like have the same configuration as in the first embodiment.

FIG. 6 is a flowchart of a fuel supply control routine according to the present embodiment.
In the present embodiment, the first and second fuel pumps 3 and 4 having different plunger diameters are selectively operated based on the accelerator operation amount (indicating the engine operating conditions) APO read in S201. . That is, when the accelerator operation amount APO is smaller than the predetermined operation amount APO1 and the operating condition of the engine is in the low load range, in S204, the first fuel pump 3 (small diameter pump 3) provided with the small diameter first plunger 302b. ) Only. When the accelerator operation amount APO is smaller than the predetermined operation amount APO2 (greater than APO1) and the engine operating condition is in the middle load range, in S205, the second plunger 402b having the large diameter is provided. Only the second fuel pump 4 (large-diameter pump) is operated. When the accelerator operation amount APO is equal to or greater than the predetermined operation amount APO2 and the engine operating condition is in the high load range, in S206, both the first and second fuel pumps 3 and 4 are operated, and in S207 The discharge amount control is executed in the same manner as S107 (S107a to 107d) in the flowchart shown in FIG. 1, and the discharge rate η2 of the second fuel pump 4 is corrected.

FIG. 7 shows a configuration of a fuel supply device for a direct injection engine according to the third embodiment of the present invention.
In the present embodiment, the first fuel pump 3 having a small capacity is relatively replaced with the pressurizing cylinders 301a and 401a, the plungers 302a and 402a, and the cams 303a and 403a of the fuel supply device according to the first embodiment. For the second fuel pump 4 having a large capacity, the first plunger 302c having a small diameter and the first cam 303c having a relatively low nose portion have a second plunger 402c having a larger diameter than the first plunger 302c. And the 2nd cam 403c whose nose part is higher than the 1st cam 303c is provided. The inner diameters of the pressure cylinders 301c and 401c of the fuel pumps 3 and 4 are adapted according to changes in the diameters of the first and second plungers 302c and 402c, as in the second embodiment. . The pressurizing cylinders 301c and 401c, the first and second plungers 302c and 402c, the elements of the fuel pumps 3 and 4 other than the first and second cams 303c and 403c, the fuel tank module 1, and the fuel injection valve About 6a-6f, the common rail 7, the engine control unit 501, etc., it is the same structure as in 1st Embodiment.

FIG. 8 is a flowchart of a fuel supply control routine according to the present embodiment.
In the present embodiment, the first and second fuel pumps 3 having different plunger diameters and cam nose heights based on the accelerator operation amount (indicating engine operating conditions) APO read in S301. , 4 are selectively activated. That is, when the engine operating condition is in the low load range, only the first fuel pump 3 including the first plunger 302c having a small diameter and the first cam 303c having a low nose portion is operated (S304). Further, when the engine operating condition is in the middle load range, only the second fuel pump 4 including the second plunger 402c having a large diameter and the second cam 403c having a high nose portion is operated (S305). When the engine operating condition is in the high load range, both the first and second fuel pumps 3 and 4 are operated (S306), and in the same manner as S107 (S107a to 107d) in the flowchart shown in FIG. The discharge amount control is executed to correct the discharge rate η2 of the second fuel pump 4 (S307).

  The case where the fuel supply apparatus according to each embodiment is applied to an in-line cylinder type direct injection engine has been described above. However, the fuel supply device according to the present invention is not limited to this, and can be applied to a V-type direct injection engine. FIG. 9 shows a configuration when applied to a V-type engine as a configuration of a fuel supply device for a direct injection engine according to the fourth embodiment of the present invention. In FIG. 9, a symbol r is assigned to an element provided corresponding to the right bank, and a symbol l is assigned to an element provided to the left bank.

  In the present embodiment, the high pressure fuel pipe 5r provided in the right bank and the high pressure fuel pipe 5l provided in the left bank are connected to the pressurizing cylinders 301a and 401a constituting the first and second fuel pumps 3 and 4, respectively. The fuel can be supplied to the fuel injection valves 6r and 6l of each bank by the first fuel pump 3, and the fuel can be supplied to the fuel injection valves 6r and 6l of each bank also by the second fuel pump 4. It is configured as follows. Switching of the operation of the first and second fuel pumps 3 and 4 is achieved by blocking the flow of fuel in the corresponding fuel pumps 3 and 4 by the electromagnetic control valves 304 and 404. The elements other than the high-pressure fuel pipe 5 such as the first and second fuel pumps 3 and 4 have the same configuration as in the first embodiment.

  In the above description, the case where the accelerator operation amount by the driver is adopted as the variable indicating the engine operating condition has been described. However, the present invention is not limited to this, and the throttle provided in the intake passage of the engine for adjusting the intake air amount is described. You may employ | adopt the opening width of a valve, or the pulse width of the drive signal output from an engine control unit with respect to a fuel injection valve.

  Further, the temperature TF of the fuel used for correcting the discharge rate η2 in the fuel supply control can be substituted with the temperature of the engine cooling water.

Configuration of engine fuel supply apparatus according to first embodiment of the present invention Flow chart of fuel supply control routine according to the embodiment Flow chart showing the contents of the discharge amount control in the same routine Change in fuel pressure between the case with the same discharge amount control and the case with the same discharge rate as a comparative example Configuration of engine fuel supply apparatus according to second embodiment of the present invention Flow chart of fuel supply control routine according to the embodiment Configuration of engine fuel supply apparatus according to third embodiment of the present invention Flow chart of fuel supply control routine according to the embodiment Configuration of engine fuel supply apparatus according to fourth embodiment of the present invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel tank module, 101 ... Feed pump, 102 ... Electric motor, 103, 104 ... Filter, 105 ... Pressure regulating valve, 2 ... Low-pressure fuel pipe, 3 ... 1st fuel pump, 301a-301c ... Pressure cylinder, 302a to 302c ... Plunger, 303a to 303c ... Cam, 304 ... Electromagnetic control valve, 305, 306 ... Check valve, 307 ... Safety valve, 308 ... Pressure attenuator, 309 ... Filter, 4 ... Second fuel pump, 401a- 401c ... Pressure cylinder, 402a to 402c ... Plunger, 403a to 403c ... Cam, 404 ... Electromagnetic control valve, 405,406 ... Check valve, 407 ... Safety valve, 408 ... Pressure attenuator, 409 ... Filter, R1, R2 ... Pressurization chamber, 5 ... high pressure fuel pipe, 6a to 6f ... fuel injection valve, 7 ... common rail, 8 ... orifice, 501 ... "control Engine control unit as chromatography Ruyunitto ", 551 ... accelerator sensor, 552 ... Crank angle sensor, 553 ... cooling water temperature sensor, 554 ... fuel temperature sensor, 555 ... fuel pressure sensor.

Claims (9)

A fuel tank for storing fuel supplied to the engine;
A first fuel pump driven by the engine and having a relatively small capacity for supplying the fuel stored in the fuel tank to the engine;
A second fuel pump having a capacity larger than that of the first fuel pump driven by the engine for supplying the fuel stored in the fuel tank to the engine;
And a control unit for outputting a command signal for selectively operating the first and second fuel pumps. The first fuel pump includes a first cam that imparts a relatively small first lift amount to the plunger;
The engine fuel supply device according to claim 1, wherein the second fuel pump includes a second cam that imparts a second lift amount larger than the first lift amount to the plunger. The first fuel pump includes a first plunger having a relatively small diameter,
The engine fuel supply device according to claim 1, wherein the second fuel pump includes a second plunger having a diameter larger than that of the first plunger. And further comprising means for detecting an operating condition of the engine,
The control unit is
When the engine operating condition is in a low load range according to the engine operating condition detected by the means, only the first fuel pump is operated among the first and second fuel pumps. When fuel is supplied and the operating condition of the engine is in a middle load range, only the second fuel pump of the first and second fuel pumps is operated to supply fuel, and the engine The engine fuel supply device according to any one of claims 1 to 3, wherein when the operating condition is in a high load range, fuel is supplied by operating both the first and second fuel pumps.   The said means detects the opening degree of the throttle valve for adjusting the amount of accelerator operation by a driver | operator, the amount of intake air, or the pulse width of the drive signal with respect to a fuel injection valve as a driving | running condition of the said engine. Engine fuel supply device. A first passage connected to the fuel tank and configured to distribute the fuel supplied to the engine by the first fuel pump; and a first passage configured to distribute the fuel supplied to the engine from the second fuel pump. A fuel supply pipe forming two passages;
A flow path cutoff valve installed in the fuel supply pipe and configured to selectively shut off the flow of fuel supplied to the engine by the first and second fuel pumps,
The engine fuel supply device according to any one of claims 1 to 5, wherein the control unit selectively operates the first and second fuel pumps by controlling the flow passage cutoff valve according to the command signal. . When operating both the first and second fuel pumps,
The control unit outputs, as the command signal, a signal for operating the first fuel pump at a discharge rate larger than that of the second fuel pump to the first and second fuel pumps. Item 7. The fuel supply device for an engine according to any one of Items 1 to 6. When operating both the first and second fuel pumps,
The control unit operates, as the command signal, the first fuel pump at a first discharge rate at a predetermined discharge amount, while the second fuel pump has a discharge amount equal to that of the first fuel pump. The engine fuel supply device according to claim 7, wherein a signal for operating at a second discharge rate is output. And further comprising means for detecting the temperature of the fuel supplied by the first fuel pump,
The control unit outputs a signal corrected based on the temperature of the fuel detected by the means to the second fuel pump as a command signal for operating both the first and second fuel pumps. The engine fuel supply device according to claim 7 or 8, wherein the engine fuel supply device outputs the fuel.

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