WO2013099533A1

WO2013099533A1 - Fuel supply device

Info

Publication number: WO2013099533A1
Application number: PCT/JP2012/081348
Authority: WO
Inventors: 晋司横田; 山口　猛
Original assignee: 株式会社豊田自動織機; トヨタ自動車株式会社
Priority date: 2011-12-27
Filing date: 2012-12-04
Publication date: 2013-07-04
Also published as: EP2799704A1; EP2799704A4; AU2012359530A1; EP2799704B1; JP2013133820A; AU2012359530B2

Abstract

A fuel supply device comprises a return flow channel (39) for merging a first return flow channel (25) with a second return flow channel (27) at a merging point (D) and returning the flow channel to a fuel tank (3). A back pressure valve (29) is provided to the return flow channel (39), and back pressure is imparted to first injectors (1a-1d) and second injectors (1e-1h). Communicating flow channels (31a, 31b) connect an intermediate pressure flow channel (13) to either the first return flow channel (25), the second return flow channel (27), or a portion upstream of the back pressure valve (29). A non-return valve (33) has lower open valve pressure than the back pressure, the non-return valve (33) is provided to the communicating flow channels (31a, 31b), and the non-return valve (33) allows fuel to be supplied from the intermediate pressure flow channel (13) to the first return flow channel (25) and the second return flow channel (27) and prevents the fuel from flowing the opposite direction.

Description

Fuel supply device

The present disclosure relates to a fuel supply device, and more particularly to a fuel supply device used for a multi-cylinder diesel engine.

As a general technique, for example, JP 2009-102990 A discloses a fuel supply apparatus. The fuel supply apparatus of the above document includes a plurality of first injectors for injecting fuel into each first combustion chamber belonging to the first cylinder group in a multi-cylinder diesel engine, and each second combustion belonging to the second cylinder group in the engine. A plurality of second injectors for injecting fuel into the chamber are connected. The fuel supply device of the above document supplies the fuel in the fuel tank to each first injector and each second injector. Each first injector and each second injector may be a piezo injector using a piezo element as an actuator for opening and closing the nozzle hole.

The fuel supply apparatus of the above literature includes an intermediate pressure pump described as a feed pump in the above literature and a high pressure pump. The intermediate pressure pump sets the fuel in the fuel tank to an intermediate pressure, and pumps the intermediate pressure fuel to the intermediate pressure flow path. The high-pressure pump makes the fuel pressure-fed in the medium-pressure channel higher than the medium pressure, and pumps the fuel made high-pressure into the high-pressure channel. The high-pressure channel is connected to the common rail. The common rail and each first injector are connected to each other by a first high-pressure channel. The common rail and each second injector are connected to each other by a second high-pressure channel.

The first return flow path connected to each first injector can transport surplus fuel in each first injector. The 2nd return flow path connected to each 2nd injector can transport the surplus fuel in each 2nd injector. The first return flow path is branched at the first branch point into a first communication flow path and a first return path. The first communication channel is connected to the intermediate pressure channel. The first return path is connected to the fuel tank. The second return channel is branched at the second branch point into a second communication channel and a second return channel. The second communication channel is also connected to the intermediate pressure channel in the same manner as the first communication channel. Similarly to the first return path, the second return path is also connected to the fuel tank.

The first back pressure valve is provided in the first return path, and the second back pressure valve is provided in the second return path. The first back pressure valve can apply back pressure to the first injector, and the second back pressure valve can apply back pressure to the second injector. The first check valve is provided in the first communication channel, and the second check valve is provided in the second communication channel. The first check valve allows the supply of fuel from the intermediate pressure flow path to the first return flow path, and prevents the reverse, that is, the supply of fuel from the first return flow path to the intermediate pressure flow path. The second check valve allows the supply of fuel from the intermediate pressure flow path to the second return flow path, and prevents the reverse, that is, the supply of fuel from the second return flow path to the intermediate pressure flow path. The valve opening pressure of the first check valve is set lower than the back pressure of the first back pressure valve. The valve opening pressure of the second check valve is set lower than the back pressure of the second back pressure valve.

In the fuel supply apparatus described in the above document, the fuel in the fuel tank is taken out by the intermediate pressure pump and pumped to the high pressure pump. And the fuel pumped by the intermediate pressure flow path is made a high pressure higher than the medium pressure by the high pressure pump, and is pumped into the common rail through the high pressure flow path. The high-pressure fuel accumulated in the common rail is injected by the first injectors into the first combustion chambers belonging to the first cylinder group in the engine, and the second injectors belonging to the second cylinder group in the engine by the second injectors. 2 It is injected into the combustion chamber.

Excess fuel in each first injector is transported to the fuel tank via the first return channel and the first return channel. Excess fuel in each second injector is transported to the fuel tank via the second return channel and the second return channel.

At this time, in the first back pressure valve, the pressure on the first return flow path side opposes the pressure on the fuel tank side, and in the second back pressure valve, the pressure on the second return flow path side opposes the pressure on the fuel tank side. . When the pressure difference between the pressure on the first return flow path side and the pressure on the fuel tank side becomes larger than the back pressure determined by the biasing force of the spring of the first back pressure valve, the first back pressure valve opens. When the differential pressure between the pressure on the second return flow path side and the pressure on the fuel tank side becomes larger than the back pressure determined by the biasing force of the spring of the second back pressure valve, the second back pressure valve opens. Thus, surplus fuel is released to atmospheric pressure via the first back pressure valve and the second back pressure valve, and returned to the fuel tank.

When the fuel in the fuel tank is empty during operation of the engine, that is, when the fuel runs out, air bubbles are mixed into the first return flow path of the first injector that is a piezo injector and the second return flow path of the second injector. The pressure in the return flow path and the second return flow path will decrease. As it is, if the fuel is replenished into the fuel tank and the engine is restarted, neither the first injector nor the second injector can inject the fuel.

For this reason, in the fuel supply device of the above document, when the fuel is replenished in the fuel tank and the engine is restarted, the intermediate pressure pump supplies the fuel to the first return channel via the first communication channel. At the same time, fuel is supplied to the second return channel via the second communication channel. At this time, in the first check valve, the pressure on the intermediate pressure pump side in the first communication flow channel opposes the pressure on the first return flow channel side, and in the second check valve, the intermediate pressure in the second communication flow channel. The pressure on the pump side opposes the pressure on the second return flow path side. When the differential pressure between the pressure on the intermediate pressure pump side and the pressure on the first return flow path side becomes larger than the valve opening pressure determined by the biasing force of the spring of the first check valve, the first check valve is open. When the pressure difference between the pressure on the intermediate pressure pump side and the pressure on the second return flow path side becomes larger than the valve opening pressure determined by the biasing force of the spring of the second check valve, the second check valve opens. Thus, the newly replenished fuel is supplied to the first return flow path at a pressure higher than the valve opening pressure of the first check valve, and the second fuel is supplied at a pressure higher than the valve opening pressure of the second check valve. Supplied to the return channel.

Here, the valve opening pressure of the first check valve is set lower than the back pressure of the first back pressure valve, and the valve opening pressure of the second check valve is set lower than the back pressure of the second back pressure valve. Yes. Therefore, the back pressure of the first back pressure valve acts on the fuel in the first return flow path, and the back pressure of the second back pressure valve acts on the fuel in the second return flow path. As a result, the pressure of the first return flow path required for fuel injection from the first injector and the pressure of the second return flow path required for fuel injection from the second injector are ensured. On the other hand, the common rail, the first high-pressure channel, and the second high-pressure channel contain high-pressure fuel supplied by the high-pressure pump when the engine is restarted after refueling. For this reason, according to the fuel supply apparatus of the said literature, it becomes possible for the 1st injector and the 2nd injector to inject fuel again.

JP 2009-102990 A

However, the fuel supply apparatus disclosed in Japanese Patent Application Laid-Open No. 2009-102990 employs a first return flow path that connects the first cylinder group to the fuel tank and a second return flow path that connects the second cylinder group to the fuel tank. In addition, a first back pressure valve and a first check valve are provided in relation to the first return flow path, and a second back pressure valve and a second check valve are provided in relation to the second return flow path. Yes.

For this reason, in the fuel supply device described above, a capacity difference and a pressure loss difference are likely to occur between the first return channel and the second return channel. A valve opening pressure difference and a flow characteristic difference are easily generated between the first check valve and the second check valve, and a back pressure difference and a flow characteristic difference are easily generated between the first back pressure valve and the second back pressure valve. . Therefore, in the fuel supply device, an injection time difference or an injection amount difference is likely to occur between the first injector and the second injector, which may affect engine startability, fuel consumption, output, exhaust performance, and the like. In order to prevent these influences, control is performed so that one of the first injector and the second injector is preferentially injected over the other, or the injection amount of the first injector and the injection amount of the second injector When the control for correcting the difference is performed or the tolerance of the parts is reduced, the manufacturing cost increases. In the fuel supply device of Document 1, the valve opening pressure of the first check valve provided in the first communication channel is set lower than the valve opening pressure of the second check valve provided in the second communication channel. By doing so, the first injector is controlled to inject with priority over the second injector. Therefore, it is necessary to always start from the first cylinder group.

In the fuel supply device described above, since the number of parts is large, the fuel supply device is increased in size and weight, and the parts cost and the management cost are increased. Furthermore, as the number of assembling steps increases, the manufacturing cost increases and it becomes difficult to mount the fuel supply device on the vehicle or the like.

The objective of this indication is providing the fuel supply apparatus which can start an engine by high quality, implement | achieving low cost of manufacture and the outstanding mounting property to a vehicle etc.
According to an aspect of the present disclosure, the fuel supply device is connected to the plurality of first injectors and the plurality of second injectors, and the fuel supply device supplies fuel to each of the first injectors and each of the second injectors. The fuel in the tank is supplied, the plurality of first injectors inject the fuel into a first fuel chamber belonging to a first cylinder group in a multi-cylinder engine, and the plurality of second injectors in a first cylinder in the engine. The fuel is injected into a second fuel chamber belonging to a two-cylinder group. Each of the first injectors and each of the second injectors is a piezo injector, and the fuel supply device is configured to inject the fuel in the fuel tank. A medium pressure pump capable of pressure-feeding; a high-pressure pump capable of pressure-feeding the fuel at a pressure higher than the medium pressure; and the high-pressure pump for each first injector and each A high-pressure channel connected to the second injector; a first return channel connected to each first injector and capable of transporting excess fuel in each first injector; connected to each second injector A second return channel capable of transporting surplus fuel in each of the second injectors; and a return channel obtained by joining the first return channel and the second return channel at a junction. The return flow path returns the surplus fuel to the fuel tank; a back pressure valve provided in the return flow path and capable of applying a back pressure to each of the first injector and each of the second injectors; An intermediate pressure flow path connected to the intermediate pressure pump; the intermediate pressure flow path with the first return flow path, the second return flow path, and a portion upstream of the back pressure valve in the return flow path; Connect to one of them The fuel flow from the intermediate pressure flow path to the first return flow path and the second return flow path is provided in the communication flow path with a valve opening pressure lower than the back pressure. And a check valve for preventing the reverse.

The fuel supply device according to this aspect employs a return flow path that joins the first return flow path and the second return flow path at the merge point, and removes excess fuel in the first injector and the second injector from the return flow path. Return to the fuel tank. For this reason, even if a capacity difference and a pressure loss difference exist between the first return channel and the second return channel, there is no capacity difference and pressure loss difference in the return channel. Therefore, according to this aspect, the influence of the return flow path from the return flow path is smaller than that of the technique of Document 1.

According to this aspect, the back pressure valve is provided in the return channel that joins the first return channel and the second return channel at the junction. As a comparative example, when a back pressure valve is provided separately for each of the first return channel and the second return channel, a back pressure difference and a flow characteristic difference are generated between the two back pressure valves. However, such a back pressure difference and a flow characteristic difference do not exist in the fuel supply device of the present disclosure.

According to this aspect, the check valve having a valve opening pressure lower than the back pressure is provided in the communication flow path connected to the intermediate pressure flow path. The intermediate pressure flow path is connected to any of the first return flow path, the second return flow path, and the upstream portion of the return flow path from the back pressure valve via the communication flow path. In the technique of Document 1, there are two return flow paths each provided with a check valve. However, the fuel supply device of the present disclosure has only one return flow path provided with one check valve. It is. For this reason, the valve opening pressure difference and the flow characteristic difference that occur when a plurality of check valves are used do not exist in this aspect.

Therefore, the difference in the injection time and the injection amount hardly occurs between the first injector and the second injector, and the engine easily exhibits excellent startability, fuel consumption, output, exhaust performance, and the like. In the fuel supply apparatus according to the present disclosure, it is not necessary to perform complicated control of the injector, and the tolerance of parts can be relatively loosened. Therefore, the manufacturing cost can be reduced.

According to this aspect, since the number of parts is small, the fuel supply device can be reduced in size and weight. In addition to the reduction in parts cost and management cost, the assembly man-hours are reduced, so that the manufacturing cost of the fuel supply device is reduced, and excellent mountability to a vehicle or the like is realized.

Therefore, according to the fuel supply device of this aspect, the engine can be started with high quality while the manufacturing cost is reduced and excellent mountability to a vehicle or the like is realized.
In the present disclosure, a gasoline engine may be employed as a multi-cylinder engine in addition to a diesel engine. When the fuel supply device of this aspect is employed in a diesel engine, a common rail may be provided between the high pressure pump and each first injector, or between the high pressure pump and each second injector.

As an aspect, the engine has an addition valve that raises the exhaust temperature of the engine by adding the fuel, and the intermediate pressure flow path connects the intermediate pressure pump to the addition valve. A particulate matter discharged from the engine may be collected by a filter provided in an exhaust gas purification catalyst or the like. In this case, the temperature of the filter is raised by the addition valve adding fuel to the exhaust gas when a certain amount of particulate matter is deposited on the filter. Thereby, the deposited particulate matter burns and the filter can be regenerated. In this aspect, since the intermediate pressure pump is connected to the addition valve via the intermediate pressure passage, it is not necessary to use a special intermediate pressure passage for connecting the intermediate pressure pump to the addition valve. For this reason, a fuel supply apparatus can be reduced in size.

In one aspect, one of the first return flow path and the second return flow path includes a first portion extending from the check valve toward the first injector, and a check valve. A second portion extending toward each of the second injectors, and the longer one of the first portion and the second portion has a larger flow path cross-sectional area than the shorter one.

In one aspect, any one of the first return flow path and the second return flow path is connected to the communication flow path at a connection point, and the first portion is connected to the first return flow path from the connection point. The second portion extends from the connection point toward each of the second injectors, and when the first portion is longer than the second portion, the flow path of the first portion The cross-sectional area is larger than the flow path cross-sectional area of the second part, and when the second part is longer than the first part, the flow cross-sectional area of the second part is the flow of the first part. It is larger than the road cross-sectional area.

In one aspect, the channel cross-sectional area of the communication channel is larger than the shorter channel cross-sectional area of the first part and the second part. In these aspects, in addition to the advantages of the fuel supply device, the capacity difference and the pressure loss difference between the first return flow path and the second return flow path can be reduced more than the technique of Document 1.

In one aspect, the first return channel and the second return channel have a length from the check valve to each first injector, and a length from the check valve to each second injector. Is configured to be equal to Also in this aspect, the capacity difference and the pressure loss difference between the first return flow path and the second return flow path can be reduced as compared with the technique of Document 1, and the fuel supply device can be downsized.

It is a schematic structure diagram of the fuel supply device of the first embodiment. It is a schematic structure diagram of the fuel supply apparatus of the second embodiment. It is a schematic structure diagram of the fuel supply device of the third embodiment.

Hereinafter, first to third embodiments embodying the present disclosure will be described with reference to the drawings.
(First embodiment)
As shown in FIG. 1, the fuel supply apparatus of the first embodiment is connected to four first injectors 1a to 1d and a plurality of second injectors 1e to 1h. The first injectors 1a to 1d inject fuel into the first combustion chambers belonging to the first cylinder group L in the multi-cylinder diesel engine. The second injectors 1e to 1h inject fuel into the second combustion chambers belonging to the second cylinder group R in the diesel engine. The fuel supply device of the first embodiment supplies the fuel in the fuel tank 3 to the first injectors 1a to 1d and the second injectors 1e to 1h. The first injectors 1a to 1d and the second injectors 1e to 1h are piezo injectors using piezo elements as actuators for opening and closing the nozzle holes, respectively.

In the fuel supply apparatus of the first embodiment, the fuel tank 3 is connected to the supply pump 5 via the supply pipe 7. The fuel filter 9 is provided in the supply pipe 7. The supply pump 5 includes an intermediate pressure pump 5a and a high pressure pump 5b.

The intermediate pressure pump 5a brings the fuel in the fuel tank 3 to an intermediate pressure of several MPa and pumps it to the pump

intermediate pressure pipes

5c and 5d. The high pressure pump 5b is connected to the intermediate pressure pump 5a via a pump intermediate pressure pipe 5c. The high pressure pump 5b can make the fuel pumped by the pump intermediate pressure pipe 5c a high pressure of several hundred MPa. The primary high-pressure pipe 11 communicates with the discharge part of the high-pressure pump 5b. The intermediate pressure pipe 13 is connected to the intermediate pressure pump 5a via the pump intermediate pressure pipe 5d.

The first common rail 15 is connected to the high-pressure pump 5b via the primary high-pressure pipe 11. The second common rail 19 is connected to the first common rail 15 via the secondary high-pressure pipe 17. The first common rail 15 is connected to the first injectors 1a to 1d via the first high-pressure pipes 21a to 21d, respectively. The second common rail 19 is connected to the second injectors 1e to 1h via the second high-pressure pipes 21e to 21h, respectively. The primary high-pressure pipe 11, the first common rail 15, and the first high-pressure pipes 21a to 21d correspond to a first high-pressure channel. The primary high-pressure pipe 11, the first common rail 15, the secondary high-pressure pipe 17, the second common rail 19, and the second high-pressure pipes 21e to 21h correspond to second high-pressure channels. The first high-pressure channel and the second high-pressure channel correspond to a high-pressure channel through which fuel flows at a high pressure.

The intermediate pressure pipe 13 branches at a first branch point A into a first intermediate pressure pipe 13a and a connection pipe 13b. The connection pipe 13b branches at the second branch point B into the second intermediate pressure pipe 13c and the first communication pipe 31a. A first addition injector 23a as a first addition valve is connected to the first intermediate pressure pipe 13a, and a second addition injector 23b as a second addition valve is connected to the second intermediate pressure pipe 13c. The first addition injector 23a and the second addition injector 23b are respectively provided upstream of the diesel particulate filter (DPF) in the exhaust gas purification catalyst. The pump

intermediate pressure pipes

5c and 5d, the intermediate pressure pipe 13, the first intermediate pressure pipe 13a, the second intermediate pressure pipe 13c, and the connection pipe 13b correspond to an intermediate pressure flow path for fuel to flow at an intermediate pressure.

The first injectors 1a to 1d are each connected to a first return pipe 25 that defines a first return flow path, and the second injectors 1e to 1h are each connected to a second return pipe 27 that defines a second return flow path. Has been. The first return pipe 25 is connected to the second connecting pipe 31b at the connection point C. The first return pipe 25 is connected to the second return pipe 27 and the first return pipe 39 at the junction point D downstream of the connection point C. The first return pipe 39 extends from the junction point D to the back pressure valve 29. The first return pipe 25, the second return pipe 27, and the first return pipe 39 form a return flow path for transporting fuel.

The first communication pipe 31a and the second communication pipe 31b form a communication flow path that connects the intermediate pressure flow path to the return flow path. The check valve 33 is provided between the first communication pipe 31a and the second communication pipe 31b. The check valve 33 allows the fuel to be supplied from the first connecting pipe 31a to the second connecting pipe 31b, and reversely, that is, prevents the fuel from being supplied from the second connecting pipe 31b to the first connecting pipe 31a. The valve opening pressure of the check valve 33 is set lower than the pressure of the return flow path.

The first return pipe 25 can transport surplus fuel in the first injectors 1a to 1d. The second return pipe 27 can transport surplus fuel in each of the second injectors 1e to 1h. The back pressure valve 29 can apply a back pressure necessary for operation to each of the first injectors 1a to 1d and each of the second injectors 1e to 1h. The downstream side of the back pressure valve 29 is connected to the second return pipe 37. The first return pipe 39 and the second return pipe 37 form a return flow path for returning the fuel to the fuel tank 3. The supply pump 5 is connected to the second return pipe 37 via the drain pipe 35a. The drain pipe 35 a is connected to the fuel tank 3 through a part of the second return pipe 37.

Drain pipes

35b and 35c are connected to the second common rail 19, and the second common rail 19 is connected to the drain pipe 35a via the drain pipe 35b and connected to the drain pipe 35a via the drain pipe 35c. Yes.

In the fuel supply device of the first embodiment, the fuel in the fuel tank 3 is taken out by the intermediate pressure pump 5a of the supply pump 5 after passing through the supply pipe 7. At this time, the foreign matter in the fuel is removed by the fuel filter 9. The fuel taken out by the intermediate pressure pump 5a is pumped to the high pressure pump 5b of the supply pump 5 to be high pressure. The high pressure fuel is pumped into the first common rail 15 through the primary high pressure pipe 11. The fuel in the first common rail 15 is pumped into the second common rail 19 via the secondary high-pressure pipe 17.

The high-pressure fuel accumulated in the first common rail 15 is injected into the first combustion chambers belonging to the first cylinder group L in the engine by the first injectors 1a to 1d. The high-pressure fuel accumulated in the second common rail 19 is injected into each second combustion chamber belonging to the second cylinder group R in the engine by each second injector 1e to 1h.

Excess fuel in each of the first injectors 1a to 1d passes through the first return pipe 25, the first return pipe 39, the back pressure valve 29, and the second return pipe 37, and is then transported to the fuel tank 3. Excess fuel in each of the second injectors 1 e to 1 h passes through the second return pipe 27, the first return pipe 39, the back pressure valve 29, and the second return pipe 37 and is then transported to the fuel tank 3.

At this time, in the back pressure valve 29, the pressure on the first return pipe 39 side opposes the pressure on the fuel tank 3 side. When the pressure difference between the pressure on the first return pipe 39 side and the pressure on the fuel tank 3 side becomes larger than the pressure required for the operation of the first injectors 1a to 1d and the second injectors 1e to 1h, the back pressure valve 29 Will open. Thus, excess fuel is released to the atmospheric pressure via the back pressure valve 29 and returned to the fuel tank 3.

When the fuel in the fuel tank 3 is empty during operation of the engine, that is, when the fuel runs out, it is connected to the first return flow path connected to the first injectors 1a to 1d, which are piezo injectors, and to the second injectors 1e to 1h. Bubbles are mixed into the second return flow path, and the pressure in the first return flow path and the second return flow path is reduced. In this state, even if it is attempted to restart the engine by replenishing the fuel into the fuel tank 3, the first injectors 1a to 1d and the second injectors 1e to 1h cannot inject fuel.

Therefore, in the fuel supply apparatus of the first embodiment, when the fuel is replenished in the fuel tank 3 and the engine is restarted, the intermediate pressure pump 5a includes the connection pipe 13b, the first communication pipe 31a, and the first The fuel is supplied to the first return pipe 25 via the two communication pipes 31b. The fuel supplied to the first return pipe 25 is also supplied from the junction D to the second return pipe 27.

At this time, in the check valve 33, the pressure on the first communication pipe 31a side connected to the intermediate pressure pump 5a opposes the pressure on the second communication pipe 31b side connected to the first return pipe 25. The pressure on the intermediate pressure pump 5a side, that is, the pressure on the first communication pipe 31a side is larger than the pressure obtained by adding the spring force of the check valve 33 to the pressure on the first return pipe 25 side, that is, the pressure on the second communication pipe 31b side. When this happens, the check valve 33 opens. In this way, the fuel newly supplied to the fuel tank 3 is supplied to the first return pipe 25 and the second return pipe 27 at a pressure higher than the valve opening pressure of the check valve 33.

The advantages of this embodiment are listed below.
(1) The valve opening pressure of the check valve 33 is set lower than the back pressure of the back pressure valve 29, that is, the pressure at which the back pressure valve 29 opens. Therefore, the back pressure of the back pressure valve 29 acts on the fuel in the first return pipe 25 and the fuel in the second return pipe 27. For this reason, the pressure of the first return flow path 25 required for fuel injection of the first injectors 1a to 1d and the pressure of the second return flow path 27 required for fuel injection of the second injectors 1e to 1h are ensured. The

(2) On the other hand, when the fuel is replenished in the fuel tank 3 and the engine is restarted, the high pressure pump 5b includes the first common rail 15, the second common rail 19, the first high pressure pipes 21a to 21d, 2. High pressure fuel is supplied to the high pressure pipes 21e to 21h. For this reason, in the fuel supply device of the first embodiment, the first injectors 1a to 1d and the second injectors 1e to 1h can again inject fuel.

(3) During this time, the fuel supply device of the first embodiment uses the first return pipe 39 and the second return pipe 37 to remove excess fuel in the first injectors 1a to 1d and the second injectors 1e to 1h. The fuel tank 3 is returned. The pipe length L2 from the check valve 33 to the second injectors 1e to 1h is larger than the pipe length L1 from the check valve 33 to the first injectors 1a to 1d. The length L1 is the sum of the length of the second connecting pipe 31b and the length of the portion upstream of the connection point C in the first return pipe 25. The length L2 is the sum of the length of the second connecting pipe 31b, the length of the portion of the first return pipe 25 on the downstream side of the connection point C, and the length of the second return pipe 27. In the first embodiment, the first return flow path 25 extends from the check valve 33 toward the first injectors 1a to 1d, and extends from the check valve 33 toward the second injectors 1e to 1h. And a second portion 25b. Specifically, the first portion 25a extends from the connection point C toward the first injectors 1a to 1d, and the length L1 is the sum of the length of the second connecting pipe 31b and the length of the first portion 25a. It is. The second portion 25b extends from the connection point C toward the second injectors 1e to 1h, and the length L2 includes the length of the second connecting pipe 31b, the length of the second portion 25b, and the second return pipe 27. It is sum. In the technique of Document 1, separate return flow paths are connected to each return flow path, but in the first embodiment, the first return pipe 25 and the second return pipe 27 are one first return at the junction D. It joins the pipe 39. For this reason, even if there is a capacity difference or a pressure loss difference between the first return pipe 25 and the second return pipe 27, there is no capacity difference or pressure loss difference in the first feedback pipe 39. That is, in the first embodiment, the influence of the return flow path from the return flow path is smaller than that of the technique of Document 1.

(4) In the fuel supply device of the first embodiment, the back pressure valve 29 is provided downstream of the first return pipe 39, that is, on the fuel tank 3 side. As a comparative example, when a back pressure valve is provided separately for each of the first return flow path and the second return flow path, a back pressure difference and a flow characteristic difference may be generated between the two back pressure valves. However, in the first embodiment, only one back pressure valve 29 is provided in the first return pipe 39 which is a part of one return flow path. For this reason, in the first embodiment, since a single back pressure valve 29 is sufficient, there is no back pressure difference or flow characteristic difference.

(5) Further, in the fuel supply device of the first embodiment, the check valve 33 having a valve opening pressure lower than the back pressure of the back pressure valve 29 is provided between the first communication pipe 31a and the second communication pipe 31b. Is provided. In the technique of Document 1, there are two return flow paths each provided with a check valve. However, in the first embodiment, there is only one return flow path provided with one check valve 33. It is. For this reason, in the first embodiment, there is no valve opening pressure difference or flow characteristic difference that occurs when a plurality of check valves are used.

(6) Thus, in the fuel supply device of the first embodiment, since the single check valve 33 and the single back pressure valve 29 are provided, the first injectors 1a to 1d and the second injectors 1e to 1h The difference in the injection time and the injection amount is less likely to occur. Therefore, the engine easily exhibits excellent startability, fuel consumption, output, exhaust performance, and the like. For this reason, in the fuel supply apparatus of the first embodiment, it is not necessary to perform complicated control of the injector, and the tolerance of parts can be relatively relaxed, so that the manufacturing cost can be reduced.

(7) Since the number of parts is small, the fuel supply device of the first embodiment can be reduced in size and weight. For this reason, in addition to the reduction in the parts cost and the management cost, the assembly man-hours are reduced, so that the manufacturing cost can be reduced, and the excellent mountability of the fuel supply device to the vehicle can be realized.

Therefore, according to the fuel supply device of the first embodiment, the engine can be started with high quality while the manufacturing cost is reduced and the excellent mountability to a vehicle or the like is realized.
(8) In the fuel supply apparatus of the first embodiment, the first addition injector 23a is connected to the first intermediate pressure pipe 13a, and the second addition injector 23b is connected to the second intermediate pressure pipe 13c. For this reason, without providing a special intermediate pressure flow path, the first addition injector 23a and the second addition injector 23b add fuel to the exhaust gas at a stage where a certain amount of the particulate material is deposited on the DPF, so that the DPF The temperature of is increased. That is, in the first embodiment, the intermediate pressure pump 5a is connected to the addition valve, that is, the first addition injector 23a and the second addition injector 23b via the intermediate pressure flow path, so that the intermediate pressure pump 5a is connected to the addition valve. There is no need to use a special medium pressure flow path. For this reason, the first embodiment realizes miniaturization of the fuel supply device.
(Second embodiment)
As shown in FIG. 2, the fuel supply device of the second embodiment is similar to the first embodiment in that the check valve 33 is longer than the length L1 of the pipe from the check valve 33 to the first injectors 1a to 1d. To the second injectors 1e to 1h is longer in the length L2.

However, in the fuel supply device of the second embodiment, the flow path cross-sectional area of the second portion 25b of the first return pipe 25 located closer to the first return pipe 39 than the connection point C is also the flow rate of the second return pipe 27a. The road cross-sectional area is also larger than the flow path cross-sectional area of the first portion 25a from the connection point C to the first injectors 1a to 1d in the first return pipe 25. Further, in the first return pipe 25, the second return pipe 27a, the first return pipe 39a, and the second communication pipe 31c, the flow path cross-sectional area of the second communication pipe 31c and the flow path cross-sectional area of the first return pipe 39a Is the largest. Other configurations of the second embodiment are the same as those of the first embodiment.

(9) For this reason, the fuel supply device of the second embodiment has a capacity difference between the first return pipe 25 and the second return pipe 27a in addition to the advantages of the fuel supply apparatus of the first embodiment. The pressure loss difference can be reduced as compared with the technique of Document 1.
(Third embodiment)
As shown in FIG. 3, in the fuel supply device of the third embodiment, the second connecting pipe 31 d is connected to the first return pipe 25 at the connection point E. In the first return pipe 25 and the second return pipe 27, the length L3 from the check valve 33 to each of the first injectors 1a to 1d is set to the length L4 from the check valve 33 to each of the second injectors 1e to 1h. It is configured to be equal. That is, the other configuration of the third embodiment is the same as that of the first embodiment.

(10) For this reason, the fuel supply apparatus of the third embodiment can further reduce the capacity difference and the pressure loss difference between the first return pipe 25 and the second return pipe 27 as compared with the technique of Document 1.
Although the present disclosure has been described with reference to the first to third embodiments, the present disclosure is not limited to the first to third embodiments, and can be modified as appropriate without departing from the spirit of the present disclosure. Needless to say, this is applicable.

For example, the communication channel is not limited to being connected to the first return pipe 25 but may be connected to the second return pipe 27 and the

first return pipes

39 and 39a.
As an industrial applicability, the present disclosure can be used for a vehicle or the like equipped with a diesel engine.

L ... 1st cylinder group 1a-1d ... 1st injector R ... 2nd cylinder group 1e-1h ... 2nd injector 3 ... Fuel tank 5a ... Intermediate pressure pump 5b ... High pressure pumps 11, 15, 17, 19, 21a-21d , 21e to 21h ... high pressure flow path (11 ... primary high pressure pipe, 15 ... first common rail, 17 ... secondary high pressure pipe, 19 ... second common rail, 21a to 21d ... first high pressure pipe, 21e to 21h ... second high pressure pipe tube)
25 ... 1st return flow path (1st return pipe)
27. Second return flow path (second return pipe)
D ...

Junction point

37, 39 ... Return flow path (37 ... 2nd return pipe, 39 ... 1st return pipe)
29 ... back

pressure valve

5c, 5d, 13, 13a, 13c, 13b ... intermediate pressure flow path (5c, 5d ... pump intermediate pressure tube, 13 ... intermediate pressure tube, 13a ... first intermediate pressure tube, 13c ... second intermediate pressure tube, 13b ... connection tube)
31a, 31b ... communication flow path (first communication pipe, second communication pipe)
33 ... Check valve 23a ... First addition valve (first addition injector)
23b ... Second addition valve (second addition injector)

Claims

A fuel supply device connected to a plurality of first injectors and a plurality of second injectors, wherein the fuel supply device supplies fuel in a fuel tank to each of the first injectors and each of the second injectors. The plurality of first injectors injects the fuel into a first fuel chamber belonging to a first cylinder group in a multi-cylinder engine, and the plurality of second injectors includes a second cylinder belonging to a second cylinder group in the engine. Injecting the fuel into the fuel chamber;
Each of the first injectors and each of the second injectors is a piezo injector,
The fuel supply device includes:
An intermediate pressure pump capable of pumping the fuel in the fuel tank at an intermediate pressure;
A high-pressure pump capable of pumping the fuel at a pressure higher than the intermediate pressure;
A high-pressure flow path connecting the high-pressure pump to each of the first injectors and each of the second injectors;
A first return flow path connected to each of the first injectors and capable of transporting excess fuel in each of the first injectors;
A second return flow path connected to each of the second injectors and capable of transporting excess fuel in each of the second injectors;
A return flow path where the first return flow path and the second return flow path are merged at a merge point, the return flow path returning the excess fuel to the fuel tank;
A back pressure valve provided in the return flow path and capable of applying a back pressure to each of the first injectors and each of the second injectors;
An intermediate pressure flow path connected to the intermediate pressure pump;
A communication flow path connecting the intermediate pressure flow path to any of the first return flow path, the second return flow path, and the upstream portion of the return flow path from the back pressure valve;
Provided in the communication flow path with a valve opening pressure lower than the back pressure, allowing supply of the fuel from the intermediate pressure flow path to the first return flow path and the second return flow path; A fuel supply device comprising a check valve for preventing the reverse.
The engine has an addition valve that increases the exhaust temperature of the engine by adding the fuel;
The intermediate pressure channel connects the intermediate pressure pump to the addition valve.
The fuel supply device according to claim 1.
Either one of the first return flow path and the second return flow path includes a first portion extending from the check valve toward each first injector, and each second injector from the check valve. A longer part of the first part and the second part has a larger channel cross-sectional area than the shorter part,
The fuel supply device according to claim 1 or 2.
Either one of the first return channel and the second return channel is connected to the communication channel at a connection point,
The first portion extends from the connection point toward the first injectors, and the second portion extends from the connection point toward the second injectors,
When the first part is longer than the second part, the flow path cross-sectional area of the first part is larger than the flow path cross-sectional area of the second part,
When the second part is longer than the first part, the flow path cross-sectional area of the second part is larger than the flow path cross-sectional area of the first part.
The fuel supply device according to claim 3.
The flow path cross-sectional area of the communication flow path is larger than the shorter flow path cross-sectional area of the first part and the second part.
The fuel supply device according to claim 3 or 4.
The first return flow path and the second return flow path are such that the length from the check valve to each first injector and the length from the check valve to each second injector are equal to each other. Configured,
The fuel supply device according to claim 1 or 2.