Engine and fuel supply system

Abstract

To provide an engine for promoting warming-up in cold starting, improving fuel economy, eliminating a common rail, reducing the number of part items, reducing weight, saving a space, and reducing cost.SOLUTION: An engine comprising: a cylinder block including a cylinder; a water jacket disposed around the cylinder; a fuel jacket disposed above the water jacket and around the cylinder; and an injector connected to the fuel jacket and configured to inject fuel into the cylinder.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to engines and fuel delivery systems. [Background technology]

[0002] A conventional vehicle engine includes a cylinder block having multiple cylinders, a water jacket arranged around the cylinders, a common rail to which fuel is supplied from a fuel tank by a fuel supply pump, fuel pipes that supply fuel from the common rail to each cylinder, and an injection device that injects fuel into the cylinders. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Takuro Mita et al., Performance Improvement of Diesel Engines by Improving Cylinder Bore Shape in Actual Operation (Part 2) - Effect of Cylinder Bore Shape on Engine Performance -, Transactions of the Society of Automotive Engineers of Japan, Vol. 54, No. 6, pp. 1110-1115, 2023 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, when an engine is started cold, it takes a certain amount of time to warm up. Furthermore, when cold fuel is injected into the cylinder (combustion chamber), the fuel absorbs heat from the air inside the cylinder, resulting in poor fuel economy. Furthermore, under operating conditions with high thermal loads that cause the engine to reach high temperatures, the upper part of the cylinder block is deformed due to thermal expansion, resulting in poor fuel economy and increased noise due to friction loss (Non-Patent Document 1).

[0005] In addition, fuel is distributed from a common rail to the injectors of each cylinder, but installing the common rail and piping requires space, which increases costs. Because the common rail has a limited volume, in a high-pressure fuel injection system, injection from one cylinder can reduce the pressure inside the common rail, which in turn reduces the supply pressure to the injectors of other cylinders, making it impossible to inject fuel at the specified pressure.

[0006] The present disclosure aims to provide an engine that accelerates warm-up during cold start, improves fuel economy, and eliminates the use of a common rail, thereby reducing the number of parts, weight, space, and cost. [Means for solving the problem]

[0007] The engine of the present disclosure has a cylinder block having a cylinder, a water jacket arranged around the cylinder, a fuel jacket arranged above the water jacket and around the cylinder, and an injector connected to the fuel jacket and configured to inject fuel into the cylinder. [Effects of the Invention]

[0008] According to the engine of the present disclosure, fuel is heated by the heat generated by combustion in the cylinders and then injected into the cylinders, which promotes warm-up, improves ignition, and improves fuel economy.In addition, by eliminating the common rail, the number of parts can be reduced, resulting in weight reduction, space savings, and cost reduction. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an engine. [Figure 2] FIG. 2 is a schematic diagram of a fuel supply system. [Figure 3] 4 is a flowchart of the operation of the fuel supply system. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the components, the arrangement positions and connection forms of the components, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not recited in independent claims will be described as optional components.

[0011] Furthermore, each drawing is a schematic diagram and is not necessarily an exact illustration. In each drawing, the same reference numerals are used to denote substantially the same components, and redundant explanations may be omitted or simplified.

[0012] 1 is a diagram showing the structure of an engine 30 according to an embodiment of the present disclosure. A plurality of cylinders 2 are formed in a cylinder block 1. Pistons 3 are movable up and down within the cylinders 2, and the lower ends of connecting rods 4 connected to the pistons 3 are connected to a crankshaft (not shown).

[0013] A water jacket 5 for cooling the engine 30 is provided around the cylinder 2, and is connected to a cooling water supply pipe and a cooling water discharge pipe (not shown). In addition, a thermometer (not shown) for measuring the temperature of the cylinder 2 is provided in the cylinder block 1.

[0014] A fuel jacket 6 is provided above the water jacket 5 around the cylinder 2, through which fuel supplied from a fuel tank (10 in FIG. 2) flows. Fuel is supplied to the fuel jacket 6 from a branch pipe 14 that branches off from a fuel supply pipe (13 in FIG. 2). Injectors (7-1, 7-2, 7-3, 7-4 in FIG. 2) are also provided in the fuel jacket 6 so as to face the inside of the cylinder 2. Relief valves (8-1, 8-2, 8-3, 8-4 in FIG. 2) are also provided in the fuel jacket 6, which return the fuel in the fuel jacket 6 to the fuel tank.

[0015] 2 is a diagram showing a fuel supply system 31 including an engine 30 according to an embodiment of the present disclosure. Four cylinders 2-1, 2-2, 2-3, and 2-4 (hereinafter sometimes collectively referred to as cylinders 2) are formed in a cylinder block 1. Fuel jackets 6-1, 6-2, 6-3, and 6-4 (hereinafter sometimes collectively referred to as fuel jackets 6) are provided around the cylinders 2-1, 2-2, 2-3, and 2-4, respectively.

[0016] The fuel jacket 6 and the fuel tank 10 are connected by a fuel supply pipe 13 and branch pipes 14-1, 14-2, 14-3, and 14-4 (hereinafter, sometimes collectively referred to as branch pipe 14). A fuel filter 11 and a fuel supply pump 12 are provided midway along the fuel supply pipe 13. In addition, a thermometer 23 that measures the temperature of the fuel in the fuel tank 10 is provided in the fuel tank 10.

[0017] The cylinder block 1 is provided with injectors 7-1, 7-2, 7-3, and 7-4 (hereinafter sometimes collectively referred to as injectors 7) that inject fuel from a fuel jacket 6 into the cylinders 2.

[0018] Discharge pipes 15-1, 15-2, 15-3, and 15-4 (hereinafter sometimes collectively referred to as discharge pipes 15) are connected to the fuel jacket 6 via relief valves 8-1, 8-2, 8-3, and 8-4 (hereinafter sometimes collectively referred to as relief valves 8). Discharge pipes 15 are connected to a fuel tank 10 by a fuel return pipe 16.

[0019] The fuel return pipe 16 is provided with a flow path switching valve 17 operated by a control device (not shown), and a branch pipe 18 branches off from the fuel return pipe 16 and is connected to the fuel tank 10. A heat exchanger 20 is provided in the branch pipe 18 and is configured to be able to cool the fuel in the branch pipe 18. Cooling water flows into the heat exchanger 20 from a cooling water inlet pipe 21 and is discharged from a cooling water outlet pipe 22, and is able to exchange heat with the fuel in the branch pipe 18. The temperature of the cooling water supplied to the heat exchanger 20 is measured by a thermometer (not shown).

[0020] With the above configuration, fuel in the fuel tank 10 is supplied by the fuel supply pump 12 through the fuel filter 11, fuel supply pipe 13, and branch pipe 14 to the fuel jacket 6. The fuel in the fuel jacket 6 cools the cylinder block 1 including the cylinder 2, and the fuel itself is heated. The heated fuel is then injected into the cylinder 2 by the injector 7.

[0021] Furthermore, the fuel in the fuel jacket 6 is returned to the fuel tank 10 through the relief valve 8, the discharge pipe 15, and the fuel return pipe 16. At this time, the flow path switching valve 17 is switched appropriately depending on the temperature of the fuel and the temperature of the cooling water in the heat exchanger 20, and under predetermined conditions, the fuel is returned to the fuel tank 10 through the branch pipe 18 and the heat exchanger 20.

[0022] 3 is a flowchart showing an example of the operation of the fuel supply system. When the engine starts, the control device starts the fuel supply pump 12 (step S1). Next, the control device compares the temperature of the fuel with the temperature of the cooling water (step S2). If the temperature of the fuel is lower (YES), the control device switches the flow path switching valve 17 to the fuel tank 10 side (the side that does not pass through the heat exchanger 20) (step S3), and the fuel that leaves the fuel jacket 6 flows back to the fuel tank 10 through the fuel return pipe 16.

[0023] If the temperature of the fuel is equal to or higher than the temperature of the cooling water in step S2 (NO), the control device switches the flow path switching valve 17 to the heat exchanger 20 side (step S4), and the fuel leaving the fuel jacket 6 flows back to the fuel tank 10 through the branch pipe 18 and the heat exchanger 20, and is cooled by heat exchange with the cooling water as it passes through the heat exchanger 20. This cools the cylinder block 1 and cools the heated fuel, so that the cylinder block 1 can be cooled effectively.

[0024] Next, the control device compares the temperature of cylinder 2 with a predetermined threshold value (step S5). The threshold value is, for example, 200°C. If the temperature of cylinder 2 is higher than the threshold value (YES), the control device increases the driving force of the fuel supply pump 12 to increase the fuel flow rate (step S6). On the other hand, if the temperature of cylinder 2 is equal to or lower than the predetermined threshold value (NO), the control device decreases the driving force of the fuel supply pump 12 to reduce the fuel flow rate (step S7). Two or more threshold values ​​can be set, in which case the driving force of the fuel supply pump 12 can be changed in three or more stages. This increases the ability to cool the cylinder when the cylinder temperature is high, and suppresses cylinder deformation.

[0025] The control device determines whether the engine has stopped (step S8), and if step S8 is NO, steps S2 to S7 are repeated until the engine has stopped (until step S8 is YES).

[0026] As described above, the engine and fuel supply system of the present disclosure heats the fuel with the heat generated by the combustion of fuel in the cylinders, improving ignition performance and fuel economy. In addition, the elimination of the common rail reduces the number of parts, resulting in weight reduction and cost reduction. [Industrial Applicability]

[0027] The present disclosure can be suitably used for engine cooling, fuel efficiency improvement, cost reduction, etc. [Explanation of symbols]

[0028] 1 Cylinder block 2 cylinders 3 pistons 4 Connecting rod 5 Water Jacket 6 Fuel jacket 7 Injectors 8 Relief valve 10. Fuel Tank 11 Fuel filter 12 Fuel supply pump 13 Fuel supply pipe 14 Branch pipe 15 Discharge pipe 16 Fuel return pipe 17 Flow path switching valve 18 Branch Pipe 20 Heat exchanger 21 Cooling water introduction pipe 22 Cooling water discharge pipe 23 Thermometer 30 Engine 31 Fuel supply system

Claims

1. a cylinder block having a cylinder; a water jacket disposed around the cylinder; a fuel jacket disposed above the water jacket and around the cylinder; an injector connected to the fuel jacket for injecting fuel into the cylinder; An engine having:

2. The engine of claim 1; A fuel tank and a fuel supply pipe for supplying fuel from the fuel tank to the fuel jacket; a fuel return pipe that returns fuel from the fuel jacket to the fuel tank; a flow path switching valve provided in the fuel return pipe and branching the flow of the fuel return pipe; a branch pipe for returning the fuel branched from the flow path switching valve to the fuel tank; a heat exchanger provided in the branch pipe for cooling the fuel flowing through the branch pipe; A fuel supply system having:

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