Throttle device

Abstract

To provide a throttle device capable of suppressing malfunction due to freezing while suppressing electric power consumption.SOLUTION: A throttle device includes: a throttle body provided in an intake passage of an engine; and a throttle valve rotatably supported by the throttle body. The throttle valve has a lower end part opposing to a lower wall of the throttle body, and a drain hole opposing to the lower end part is formed on the lower wall. The drain hole includes an on-off valve for opening the drain hole in a non-energized state when the engine is stopped.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a throttle device. [Background technology]

[0002] Water droplets that have formed between the throttle valve and the throttle body may freeze while the engine is stopped, hindering the operation of the throttle valve. For this reason, by repeatedly opening and closing the throttle valve when the engine is stopped to disperse the water droplets from the throttle valve, malfunctions caused by freezing can be suppressed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-089538 Summary of the Invention [Problem to be solved by the invention]

[0004] However, repeated opening and closing of the throttle valve as described above may increase power consumption.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a throttle device that can suppress malfunctions due to freezing while suppressing power consumption. [Means for solving the problem]

[0006] The above object can be achieved by a throttle device comprising a throttle body provided in an intake passage of an engine, and a throttle valve rotatably supported by the throttle body, wherein the throttle valve has a lower end portion facing a lower wall of the throttle body, a drain hole facing the lower end portion is formed in the lower wall, and an opening / closing valve is provided in the drain hole to open the drain hole in a non-energized state when the engine is stopped. [Effects of the Invention]

[0007] A throttle device can be provided that can suppress malfunctions due to freezing while suppressing power consumption. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of the engine system. [Figure 2] 2A to 2C are explanatory diagrams of a throttle device of a comparative example. [Figure 3] 3A to 3C are explanatory diagrams of the throttle device of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Engine system overview] FIG. 1 is a schematic diagram of an engine system 100. The engine system 100 is mounted, for example, on a vehicle, but is not limited to this. The engine system 100 includes an engine 10, an ECU (Electronic Control Unit) 25, a PCV structure 30, and a throttle device 40. The engine 10 is, for example, a gasoline engine. The engine 10 includes a cylinder block 20, a cylinder head 21, a crankcase 27, a fuel injector 13, a piston 24, a crankshaft 22, an intake valve 17, and an exhaust valve 19. The cylinder head 21 is attached to the top of the cylinder block 20. The crankcase 27 is attached below the cylinder block 20. The crankshaft 22 is housed inside the crankcase 27. One end of a connecting rod 23 is connected to the piston 24, and the other end is connected to the crankshaft 22. A combustion chamber 26 is defined by the cylinder block 20, the cylinder head 21, and the piston 24.

[0010] An intake valve 17, an exhaust valve 19, and a fuel injection valve 13 are provided in a cylinder head 21. The fuel injection valve 13 performs in-cylinder injection. An intake passage 12 and an exhaust passage 14 are connected to the cylinder head 21. In the intake passage 12, an air cleaner 15, an air flow meter 16, and a throttle device 40 are provided, in this order from the upstream side. The air cleaner 15 removes dust and other particles from the air in the intake passage 12. The air flow meter 16 detects the flow rate of air in the intake passage 12.

[0011] The throttle device 40 has a throttle body 42 and a throttle valve 44. The throttle body 42 is provided midway through the intake passage 12 and is part of the piping for introducing air. The throttle valve 44 is rotatably provided inside the throttle body 42. The throttle body 42 is provided with a drain hole 42h and an on-off valve 43, which will be described in detail later.

[0012] Air in the intake passage 12 is introduced into the combustion chamber 26 in response to the opening of the intake valve 17. The fuel injection valve 13 injects fuel into the combustion chamber 26. A mixture of fuel and air is produced in the combustion chamber 26. For example, the mixture is ignited by a spark plug (not shown), and combustion of the mixture causes the piston 24 to reciprocate and the crankshaft 22 to rotate. When the exhaust valve 19 opens, the exhaust gas after combustion is discharged into the exhaust passage 14.

[0013] Unburned gas (blow-by gas) may leak from the combustion chamber 26 into the crankcase 27. The PCV structure 30 is a device for returning the blow-by gas from the crankcase 27 to the intake passage 12. The PCV structure 30 has a PCV passage 32 and a PCV piping 34. The PCV passage 32 is provided inside the cylinder block 20 and the cylinder head 21, and extends to the crankcase 27.

[0014] The PCV piping 34 is provided outside the engine 10 and extends from the engine 10 to the intake passage 12. One end of the PCV piping 34 is connected to the cylinder head 21 of the engine 10 and communicates with the PCV passage 32. The other end of the PCV piping 34 is connected to the intake passage 12 downstream of the throttle valve 44. Blow-by gas flows through the PCV passage 32 and the PCV piping 34 and is supplied from the crankcase 27 to the intake passage 12. The blow-by gas is introduced into the combustion chamber 26 together with air and is burned.

[0015] The ECU 25 is a control device that includes a calculation device such as a CPU (Central Processing Unit), and storage devices such as a flash memory, a ROM (Read Only Memory), and a RAM (Random Access Memory). The ECU 25 acquires the air flow rate detected by the air flow meter 16. The ECU 25 controls the amount and timing of fuel injection from the fuel injection valve 13. The ECU 25 controls the opening degree of the throttle valve 44. The ECU 25 also controls the open / close state of the on-off valve 43.

[0016] [Throttle device of comparative example] Before describing the throttle device 40 of this embodiment, a throttle device 40x of a comparative example will be described below. Figures 2A to 2C are explanatory diagrams of the throttle device 40x of the comparative example. The air cleaner 15 of Figure 1 and the like are provided upstream of the throttle body 42. The PCV piping 34 and the engine 10 are located downstream of the throttle body 42.

[0017] The throttle body 42 has a lower wall 42a and an upper wall 42b that face each other vertically, and a pair of side walls 42c that face each other horizontally. The throttle valve 44 is, for example, a butterfly valve, and has a shaft 46 and a valve element 48. The shaft 46 is rotatably supported between the pair of side walls 42c of the throttle body 42. The valve element 48 is a plate-shaped member that can rotate around the shaft 46. Figures 2A to 2C show the throttle valve 44 in a state where it is slightly open. The valve element 48 has a lower end 48a and an upper end 48b that face the lower wall 42a and the upper wall 42b, respectively.

[0018] 2A shows the throttle device 40x when the engine 10 is stopped and the throttle valve 44 is in a non-energized state. The valve body 48 is slightly inclined relative to a direction perpendicular to the lower wall 42a. Specifically, the lower end 48a of the valve body 48 faces upstream, and the upper end 48b faces downstream.

[0019] 2A, a plurality of pieces of ice 60 adhere to the throttle valve 44. This is because moisture contained in blow-by gas and the like adheres to the throttle body 42 and the throttle valve 44 while the vehicle is running. In addition, intake air flows into the throttle body 42 from the upstream side. If the temperature of the intake air is, for example, around 0°C, the moisture freezes, and ice 60 forms on the upstream surface of the valve disc 48.

[0020] When the engine 10 is stopped, the flow of intake air into the throttle body 42 from the upstream side stops, and residual heat from the engine 10 is transferred to the valve disc 48 from the downstream side. This causes the ice 60 to melt and turn into water droplets, which flow toward the lower end 48a of the valve disc 48. As a result, as shown in FIG. 2B, water droplets 62 adhere between the lower end 48a of the valve disc 48 and the lower wall 42a of the throttle body 42. After the engine 10 has been stopped for several hours, for example, the water droplets 62 freeze to form ice 64, as shown in FIG. 2C. The ice 64 is larger than the ice 60 shown in FIG. 2A and is frozen in contact with the lower end 48a of the valve disc 48 and the lower wall 42a. This could impede the operation of the valve disc 48.

[0021] For example, it is conceivable to repeatedly open and close the throttle valve 44 in the state of Figure 2B to cause the water droplets 62 to scatter from the valve body 48. However, there is a risk that such repeated opening and closing operations will increase power consumption.

[0022] [Throttle device of this embodiment] 3A to 3C are explanatory diagrams of the throttle device 40 of this embodiment. In this embodiment, unlike the comparative example, a drain hole 42h is formed in the lower wall 42a of the throttle body 42. Specifically, the drain hole 42h faces the lower end 48a of the valve body 48. The drain hole 42h is a hole that penetrates downward from the lower wall 42a. An on-off valve 43 is provided in the drain hole 42h and opens and closes the drain hole 42h. The on-off valve 43 is a so-called normally open solenoid valve that opens the drain hole 42h in a non-energized state. Therefore, when the engine 10 is running, the ECU 25 energizes the on-off valve 43 to close the drain hole 42h. When the engine 10 is stopped, the ECU 25 stops energizing the on-off valve 43, and the on-off valve 43 maintains the drain hole 42h in an open state.

[0023] 3A and 3B, the ice 60 melts due to the residual heat of the stopped engine 10, and water droplets 62 adhere to the lower end 48a of the valve body 48. As described above, the on-off valve 43 opens the drain hole 42h. Therefore, as shown in FIG. 3C, the water droplets 62 are discharged from the lower end 48a of the valve body 48 through the drain hole 42h to the outside of the throttle body 42. Therefore, unlike the comparative example, the operation of the throttle valve 44 is less likely to be hindered by ice 64.

[0024] In this way, since the on-off valve 43 opens the drain hole 42h in the de-energized state, the water droplets 62 are discharged from the drain hole 42h. Therefore, it is not necessary to repeatedly open and close the throttle valve 44 in order to splash the water droplets 62 away from the valve body 48. This also reduces power consumption.

[0025] It is preferable that the drain hole 42h be located upstream of the lower end 48a of the valve body 48 when the throttle valve 44 is fully closed. This is because it is possible to prevent intake air from being introduced into the engine 10 through the drain hole 42h when the throttle valve 44 is fully closed.

[0026] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0027] 10 Engine 12 Intake passage 40 Throttle device 42 Throttle body 42a Lower wall 42h Drain hole 43 On-off valve 44 Throttle valve 46 axes 48 Valve body 48a Bottom end 60, 64 Ice 62 water drops

Claims

[Claim 1] A throttle body provided in an intake passage of the engine; a throttle valve rotatably supported by the throttle body, the throttle valve has a lower end portion facing a lower wall of the throttle body, The lower wall is formed with a drain hole facing the lower end portion, The drain hole is provided with an open / close valve that opens the drain hole in a non-energized state when the engine is stopped.

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