JP2005163685A - Fuel heating apparatus for fuel injection type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel heating device of a fuel injection type internal combustion engine having a simple configuration and capable of stably heating fuel without a difference in fuel temperature between cylinders.
SOLUTION: A fuel delivery pipe 20 for supplying fuel to a plurality of fuel injection valves 13 arranged in parallel is provided with a heat exchanger 50 along its longitudinal direction, and an internal passage 53 of the heat exchanger 50 is connected to the heat exchanger. The heat exchanger inlet 51 and the heat exchanger outlet 52 arranged in parallel at one end in the longitudinal direction are formed in U-shapes of an outward path 53I and a return path 53O, respectively, and engine cooling water from the cylinder head outlet is supplied to the heat exchanger inlet 51 to be introduced.
[Selection] Figure 3

Description

  The present invention relates to a fuel heating apparatus for a fuel injection type internal combustion engine in which fuel is supplied to an engine by a fuel injection valve.

  As in-vehicle gasoline engines, there are known port injection engines in which fuel is injected from the fuel injection valve toward the intake port, and direct injection (in-cylinder injection) engines in which fuel is directly injected into the combustion chamber from the fuel injection valve. It has been. In such an engine, it is preferable that the injected fuel is sufficiently vaporized to form a good air-fuel mixture.

  Thus, for example, Patent Document 1 discloses a technique for adjusting the fuel temperature with engine cooling water flowing through a heater core. In the one described in Patent Document 1, the temperature of the cooling water flowing out from the heater core is varied within a predetermined range by adjusting the flow rate of the cooling water to the heater core, and the fuel temperature is controlled. doing.

  By the way, in a direct injection engine, since fuel is directly injected into the combustion chamber from the fuel injection valve, there is a risk that the time for the fuel to evaporate will be insufficient, resulting in insufficient formation of a good mixture, and incomplete combustion. There is a concern that the output will decrease due to the above and exhaust emissions will deteriorate. Therefore, in Patent Document 2, in order to heat the fuel in the delivery pipe that supplies high-pressure fuel to the fuel injection valve, the engine cooling water is supplied to the delivery pipe integrated into the cylinder block, or two V-types. A technique for circulating around a delivery pipe provided between banks is disclosed. That is, in the thing of patent document 2, it is intended for the direct-injection engine which injects fuel directly into the cylinder of an engine, and engine cooling water held at a predetermined temperature is integrated into a cylinder block or V-shaped The fuel is circulated around a delivery pipe provided between the two banks to heat the fuel.

JP-A-8-93579 JP 2000-145571 A

  However, in the thing of patent document 1, the temperature of the cooling water which flows out of a heater core is adjusted in the predetermined range by adjusting the flow volume of the cooling water to a heater core, and fuel temperature is controlled. The piping for the engine was complicated and was insufficient to heat the fuel to a high temperature for a direct injection engine. In the direct injection type engine, the fuel pressure supplied to the fuel injection valve is higher than the fuel pressure of the port injection type engine, and therefore, the fuel temperature suitable for promoting vaporization of fuel does not occur and vapor is high. It is. In this regard, the one described in Patent Document 2 distributes engine cooling water maintained at a predetermined temperature around a delivery pipe integrated into a cylinder block or provided between two V-shaped banks. Since the fuel is heated, a high fuel temperature can be obtained, but on the other hand, there is a possibility that a difference in fuel temperature between cylinders may occur because it is simply circulating around, and the structure is There was a problem of complexity.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel that can be stably heated with a simple configuration without a difference in fuel temperature between cylinders. An object of the present invention is to provide a fuel heating device for an injection type internal combustion engine.

  In order to achieve the above object, a fuel heating apparatus for a fuel injection internal combustion engine according to an aspect of the present invention is provided along a longitudinal direction of a fuel delivery pipe for supplying fuel to a plurality of fuel injection valves arranged in parallel. A heat exchanger is provided, and an internal passage of the heat exchanger is formed in a U shape that communicates with a heat exchanger inlet and a heat exchanger outlet arranged in parallel at one end in the longitudinal direction of the heat exchanger. The engine cooling water is introduced into the inlet of the heat exchanger.

  In the present specification, the “fuel delivery pipe” includes the above-described delivery pipe and the like, and a pipe having an enlarged common fuel chamber that communicates with a plurality of supply pipes respectively connected to a plurality of fuel injection valves. Say.

  Here, it is preferable to further include a bypass passage branched from between the cylinder head outlet and the heat exchanger inlet, and a flow rate adjusting valve provided in the bypass passage.

  Moreover, it is preferable to further comprise control means for controlling the flow rate adjusting valve in accordance with the fuel temperature.

  The fuel flow control valve may further include means for increasing the amount of fuel supplied to the fuel injection valve when the flow regulating valve is fixed on the closed side.

  According to the fuel heating apparatus for a fuel injection internal combustion engine according to an aspect of the present invention, the engine coolant from the cylinder head outlet is along the longitudinal direction of the fuel delivery pipe that supplies fuel to the plurality of fuel injection valves arranged in parallel. It is introduced into the heat exchanger provided. The introduced cooling water flows through the U-shaped internal passage communicating with the heat exchanger inlet and the heat exchanger outlet arranged in parallel at one end in the longitudinal direction of the heat exchanger. The fuel temperature inside is uniformly and stably heated without any difference between cylinders. In addition, by introducing the engine coolant from the cylinder head outlet into the heat exchanger, the piping of the coolant passage does not become complicated, and the engine coolant temperature corresponding to the fuel injection amount that varies substantially according to the engine load. Since the fuel is heated by the above, the temperature of the fuel is stabilized. Furthermore, by providing a heat exchanger directly in the fuel delivery pipe, it can be easily configured without increasing the number of parts.

  Further, according to the configuration further including the bypass passage branched from between the cylinder head outlet and the heat exchanger inlet and the flow rate adjusting valve provided in the bypass passage, the temperature of the fuel can be controlled.

  Further, according to the configuration further comprising a control means for controlling the flow rate adjusting valve according to the fuel temperature, the temperature of the fuel can be controlled with higher accuracy.

  In addition, when the flow rate adjusting valve is fixed on the closed side, the fuel temperature can be prevented from excessively rising according to the configuration further comprising means for increasing the amount of fuel supplied to the fuel injection valve.

  Hereinafter, an embodiment in which a fuel heating device for a fuel injection internal combustion engine according to the present invention is applied to a direct injection gasoline engine as a fuel injection internal combustion engine will be described with reference to the drawings.

  In FIG. 1, the outline | summary of the direct-injection gasoline engine 10 in this embodiment is shown with sectional drawing. The engine 10 includes a cylinder block 11 and a cylinder head 12, a fuel injection valve 13 is provided in the cylinder head 12, and a fuel delivery pipe provided with a heat exchanger as will be described later. The high pressure fuel from 20 is supplied through a fuel supply pipe 21. The high-pressure fuel from the fuel injection valve 13 is directly injected into the combustion chamber 17 in each cylinder defined when the intake valve 15 and the exhaust valve 16 are closed above the piston 14 of the engine 10. Reference numeral 18 denotes a spark plug provided substantially on the center line of the cylinder.

  Here, the fuel supply system in the present embodiment will be described. A low-pressure fuel primary pump 31 is connected to the fuel tank 30, and a high-pressure fuel secondary pump 32 is connected to the fuel primary pump 31. Yes. The fuel secondary pump 32 is connected to the fuel delivery pipe 20 via the fuel pressure adjustment valve 33, increases the pressure of the fuel supplied from the fuel primary pump 31 to a predetermined adjustment pressure, and supplies it to the fuel delivery pipe 20. It is like that. Then, high-pressure fuel from the fuel delivery pipe 20 is supplied to each fuel injection valve 13 via the fuel supply pipe 21, and fuel is injected from the fuel injection valve 13.

  Although not shown, the fuel delivery pipe 20 is provided with a fuel pressure sensor and outputs a detection value corresponding to the fuel pressure in the fuel delivery pipe 20 to a controller (not shown). Based on the detected value of the fuel pressure sensor, the controller controls the drive of the fuel secondary pump 32 and the fuel pressure adjustment valve 33 so that the fuel pressure in the fuel delivery pipe 20 becomes the target fuel pressure. Although not shown, the fuel delivery pipe 20 is provided with a fuel temperature sensor and outputs a detection value corresponding to the fuel temperature in the fuel delivery pipe 20 to the controller. Based on the detected value of the fuel temperature sensor and the coolant temperature, the controller controls a flow rate control valve 45, which will be described later, in order to bring the fuel temperature in the fuel delivery pipe 20 to the target fuel temperature. Note that the temperature of the fuel in the fuel delivery pipe 20 can be estimated based on detection values obtained by existing sensors such as the coolant temperature, the engine oil temperature, and the intake air temperature without providing a fuel temperature sensor.

  Next, a schematic configuration of the cooling water circulation system of the fuel delivery pipe 20 provided with the heat exchanger in the present embodiment will be described with reference to FIG. As shown in FIG. 2, the cooling water circulation system includes a radiator 40, a first cooling water passage 41 that connects an outlet of the radiator 40 and a cylinder block inlet of an engine 10 provided with a water pump (not shown), A coolant passage that circulates through the engine, a second coolant passage 42 that connects the cylinder head outlet of the engine 10 and the inlet of the heat exchanger 50, and a third coolant that connects the outlet of the heat exchanger 50 and the inlet of the radiator 40. The cooling water passage 43 is configured to include a bypass passage 44 that connects the second cooling water passage 42 and the third cooling water passage 43 and is provided with the above-described flow rate adjustment valve 45. Cooling of the engine 10 and heating of the fuel delivery pipe 20 by the heat exchanger 50 are performed by operating a water pump and circulating cooling water in the cooling water circulation system.

  Here, the details of the fuel delivery pipe 20 provided with the heat exchanger 50 in the present embodiment will be described with reference to FIGS. 3 (A) and 3 (B). FIG. 3A is a partial cross-sectional view of the heat exchanger 50 shown with the fuel delivery pipe 20 omitted for ease of understanding, and FIG. 3B shows the fuel delivery pipe 20 omitted. It is the BB sectional view taken on the line in FIG.

  The fuel delivery pipe 20 has a common fuel chamber in which fuel supply pipes 21 having a common length are arranged in parallel to communicate with a plurality of fuel injection valves 13 provided in parallel corresponding to the cylinders. The heat exchanger 50 is provided along the longitudinal direction so as to contact and cover the outside of the common fuel chamber of the fuel delivery pipe 20. A heat exchanger inlet 51 and a heat exchanger outlet 52 are juxtaposed at one end in the longitudinal direction of the heat exchanger 50, and the second cooling water passage 42 and the third cooling water passage 43 are respectively connected to the heat exchanger 50. ,It is connected. The internal passage 53 of the heat exchanger 50 is formed in a U shape including an outward path 53 </ b> I connected to the heat exchanger inlet 51 and a return path 53 </ b> O connected to the heat exchanger outlet 52. Further, the heat exchanger 50 is entirely covered with a heat insulating material 60 together with the fuel delivery pipe 20.

  In the cooling water circulation system, the cooling water from the water pump normally passes through the cylinder block 11 and the cylinder head 12 of the engine 10 to cool the engine 10. Cooling water heated by heat exchange with the engine 10 is guided from the cylinder head outlet to the inlet of the radiator 40 through the second cooling water passage 42, the heat exchanger 50, and the third cooling water passage 43. When the cooling water temperature is lower than a predetermined value, the water path to the radiator 40 is closed by a thermostat (not shown), and the cooling water is returned to the water pump without passing through the radiator 40. On the other hand, when the heat exchange with the engine 10 is performed and the cooling water becomes higher than a predetermined temperature, the water path to the radiator 40 is opened by the thermostat, and the cooling water is introduced into the radiator 40. The cooling water is cooled when passing through the radiator 40, and then returned to the water pump again through the first cooling water passage 41. The cooling water after the engine 10 is warmed up is maintained at a predetermined temperature by the action of the thermostat.

  Next, the operation of the fuel heating device for engine 10 according to the present embodiment configured as described above will be described. During operation of the engine 10, the temperature of each part of the engine 10 rises due to combustion in the combustion chamber 17. Heated cooling water is exchanged with the engine 10 and introduced into the heat exchanger 50 from the cylinder head outlet via the second cooling water passage 42. The cooling water flowing in from the heat exchanger inlet 51 at one end of the heat exchanger 50 first flows through the forward path 53I, then makes a U-turn and flows through the return path 53O, and then the heat exchanger at one end of the heat exchanger 50 It flows out from the outlet 52 to the third cooling water passage 43. When the coolant passes through the forward path 53I and the return path 53O of the internal passage 53, the high-pressure fuel in the fuel delivery pipe 20 is heated. As the temperature in the heat exchanger 50 circulates, the temperature of the cooling water gradually decreases due to heat exchange, and the internal passage 53 is configured by an outward path 53I and a return path 53O that can flow in a U-turn. As a result, the high-pressure fuel in the fuel delivery pipe 20 can be heated to a uniform temperature with no temperature difference between the cylinders. In addition, the engine coolant from the cylinder head outlet is introduced into the heat exchanger 50 via the second coolant passage 42, so that the piping of the coolant passage is not complicated, and the engine coolant is substantially reduced depending on the engine load. Since the fuel is heated by the engine coolant temperature corresponding to the varying fuel injection amount, the temperature of the fuel can be stabilized. The high-temperature fuel is supplied to the fuel injection valve 13 through the fuel supply pipe 21 and directly injected into the fuel chamber 17 in each cylinder.

  Further, as shown in FIG. 2, a flow rate adjustment valve 45 provided in a bypass passage 44 branched from a second cooling water passage 42 connected to the outlet of the cylinder head 12 and the heat exchanger inlet 51 is provided with a fuel delivery. It is controlled by the controller based on the detected value detected by the fuel temperature sensor provided in the pipe 20 or the aforementioned estimated value and the coolant temperature. That is, the flow rate of the cooling water passing through the bypass passage 44 and the flow rate of the cooling water flowing through the heat exchanger 50 are controlled so that the fuel temperature in the fuel delivery pipe 20 becomes the target fuel temperature. This control is performed in consideration of the heat capacity of the cooling water and fuel used for heat exchange. For example, when the coolant temperature immediately after start-up is low, a predetermined heat capacity for heat exchange is ensured by increasing the coolant flow rate, or when the target fuel temperature is high and the fuel flow rate is large, a large amount The high temperature cooling water is controlled to be sent to the heat exchanger 50. Therefore, when the cooling water having a large heat capacity is required, the flow rate control valve 45 is completely closed or throttled so that the cooling water flow rate through the bypass passage 44 is controlled to a small flow rate, and the heat exchanger 50 is The flow rate of circulating coolant is increased. On the contrary, when cooling water with a small heat capacity is required, the flow rate control valve 45 is opened, the cooling water flow rate through the bypass passage 44 is controlled to a large flow rate, and the cooling water flowing through the heat exchanger 50 is The flow rate is reduced. The flow control valve 45 may be either an on-off type or a continuous type.

  As a fail-safe when the flow rate adjusting valve 45 is stuck on the closed side, this is detected by an appropriate sensor or diagnostic control in the controller, and supplied to the combustion chamber to prevent an excessive increase in fuel temperature. Means for increasing the amount of fuel may be provided. However, in this case, it is preferable to adjust the engine output by simultaneously operating torque reducing means such as ignition retarding means in accordance with the amount of fuel increase. In the case of the direct injection engine described above, the fuel pressure in the fuel delivery pipe 20 is first raised by controlling the fuel pressure adjusting valve 33 to prevent the fuel from boiling, and when the temperature further rises, The fuel supplied to the combustion chamber is increased by the injection valve 13 to lower the fuel temperature. On the other hand, in the case of a port injection type engine as another embodiment, the amount of fuel injected by the fuel injection valve is simply increased to lower the fuel temperature.

It is a partial cross section side view which shows one embodiment of this invention. It is a partial cross section top view which shows one embodiment of this invention. (A) is the fragmentary sectional view of the heat exchanger which abbreviate | omitted and illustrated fuel delivery piping of one embodiment of this invention, (B) showed without omitting fuel delivery piping (A) It is BB sectional drawing in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 12 Cylinder head 13 Fuel injection valve 20 Fuel delivery piping 30 Fuel tank 31 Fuel primary pump 32 Fuel secondary pump 41 First cooling water passage 42 Second cooling water passage 43 Fourth cooling water passage 44 Bypass passage 45 Flow Control Valve 50 Heat Exchanger 51 Heat Exchanger Inlet 52 Heat Exchanger Outlet 53 Internal Passage 53I Outgoing 53O Return

Claims (4)

  A fuel delivery pipe that supplies fuel to a plurality of fuel injection valves arranged in parallel is provided with a heat exchanger along the longitudinal direction thereof, and an internal passage of the heat exchanger is arranged in parallel with one end portion in the longitudinal direction of the heat exchanger. A fuel injection type internal combustion engine which is formed in a U shape communicating with the heat exchanger inlet and the heat exchanger outlet, and is configured to introduce engine coolant from the cylinder head outlet into the heat exchanger inlet. Fuel heating device.   2. The fuel injection internal combustion engine according to claim 1, further comprising: a bypass passage that branches from between the cylinder head outlet and the heat exchanger inlet; and a flow rate adjusting valve provided in the bypass passage. Fuel heating device.   The fuel heating apparatus for a fuel injection type internal combustion engine according to claim 2, further comprising control means for controlling the flow rate adjusting valve according to fuel temperature.   4. The fuel heating of a fuel injection type internal combustion engine according to claim 2, further comprising means for increasing the amount of fuel supplied to the fuel injection valve when the flow rate adjusting valve is fixed on the closed side. apparatus.

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