Control device for internal combustion engine

Abstract

To provide a control device for an internal combustion engine which can eliminate knocking without lowering output performance in an internal combustion engine that uses gas fuel.SOLUTION: A control device for an internal combustion engine comprises: a pressure regulator 44 for decompressing compressed gas fuel and supplying the same to a gas fuel supply device 41; a first cooling path C1 for supplying cooling water for the engine 2 to the pressure regulator 44; a water-cooling type intercooler 23 for cooling air being sucked into the engine 2; a knock sensor 34 for detecting knocking of the engine 2; a second cooling path C2 for making the cooling water circulate between the pressure regulator 44 and the intercooler 23; and a control unit 3 for decreasing a quantity of cooling water supplied to the pressure regulator 44 and increasing a quantity of cooling water supplied to the intercooler 23 when a temperature of the pressure regulator 44 is higher than a prescribed temperature, a knocking has been detected, and a temperature of air supplied from the intercooler 23 is higher than a prescribed temperature.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for an internal combustion engine.

Background Art

[0002] Patent Document 1 describes that in an air-fuel ratio control device for an internal combustion engine provided with feedback control means, cooling water temperature detection means and intake air temperature detection means are provided, and when the cooling water temperature is greater than a set value and the intake air temperature is greater than a set value, correction control means for increasing the fuel amount is provided.

[0003] Also, when knocking is detected, ignition timing retard control is performed, and retard amount monitoring means for monitoring the retard amount is provided. When the cooling water temperature is greater than a set value, the intake air temperature is greater than a set value, and further the retard amount is greater than a set value, correction control means for increasing the fuel amount is provided.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, there is an internal combustion engine that uses gaseous fuel such as natural gas. When knocking occurs in such an internal combustion engine, the ignition timing is retarded, but there is a risk of causing a decrease in output performance.

[0006] Therefore, an object of the present invention is to provide a control device for an internal combustion engine that can eliminate knocking without reducing the output performance in an internal combustion engine using gaseous fuel.

Means for Solving the Problems

[0007] To solve the above problems, the present invention provides a gas fuel supply device for supplying gas fuel to an intake port of an internal combustion engine, a decompression unit for decompressing the compressed gas fuel and supplying it to the gas fuel supply device, a first cooling path for supplying cooling water of the internal combustion engine to the decompression unit, a water-cooled intercooler for cooling the air inhaled into the internal combustion engine, and a knocking detection unit for detecting knocking of the internal combustion engine. A control device for an internal combustion engine, which is independent of the first cooling path, and a second cooling path for circulating cooling water between the decompression unit and the intercooler, and a first flow rate adjustment unit for adjusting the flow rate of the cooling water in the first cooling path. , a second flow rate adjustment unit for adjusting the flow rate of the cooling water in the second cooling path, when the temperature of the decompression unit is higher than a predetermined temperature, knocking is detected by the knocking detection unit, and the temperature of the air supplied from the intercooler to the internal combustion engine is higher than the predetermined temperature. In this case, a control unit that reduces the amount of cooling water supplied to the decompression unit by the first flow rate adjustment unit while increasing the amount of cooling water supplied to the intercooler by the second flow rate adjustment unit is provided.

Effect of the Invention

[0008] Thus, according to the present invention, in an internal combustion engine using gas fuel, knocking can be eliminated without degrading the output performance.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0010] A control device for an internal combustion engine according to an embodiment of the present invention includes a gaseous fuel supply device that supplies gaseous fuel to an intake port of the internal combustion engine, a decompression unit that decompresses the compressed gaseous fuel and supplies it to the gaseous fuel supply device, a first cooling path that supplies cooling water of the internal combustion engine to the decompression unit, a water-cooled intercooler that cools the air inhaled into the internal combustion engine, and a knocking detection unit that detects knocking of the internal combustion engine. The control device for the internal combustion engine is configured to include a second cooling path that is independent of the first cooling path and circulates cooling water between the decompression unit and the intercooler, a first flow rate adjustment unit that adjusts the flow rate of the cooling water in the first cooling path, a second flow rate adjustment unit that adjusts the flow rate of the cooling water in the second cooling path, and a control unit that, when the temperature of the decompression unit is higher than a predetermined temperature, knocking is detected by the knocking detection unit, and the temperature of the air supplied from the intercooler to the internal combustion engine is higher than the predetermined temperature, reduces the amount of cooling water supplied to the decompression unit by the first flow rate adjustment unit while increasing the amount of cooling water supplied to the intercooler by the second flow rate adjustment unit.

[0011] Thereby, the control device for an internal combustion engine according to an embodiment of the present invention can eliminate knocking without degrading the output performance in an internal combustion engine that uses gaseous fuel.

Example

[0012] Hereinafter, with reference to the drawings, a control device for an internal combustion engine according to an embodiment of the present invention will be described in detail.

[0013] In FIG. 1, a vehicle 1 equipped with a control device for an internal combustion engine according to an embodiment of the present invention includes an internal combustion engine type engine 2 and a control unit 3.

[0014] A plurality of cylinders are formed in the engine 2. In the present embodiment, the engine 2 is configured to perform a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke for each cylinder. The engine 2 is provided with a knock sensor 34 as a knocking detection unit that detects knocking of the engine 2.

[0015] In addition, in this embodiment, it is assumed that the engine 2 is composed of an in-line four-cylinder engine. However, in the present invention, it may be composed of various types of engines such as an in-line six-cylinder engine, a V-type six-cylinder engine, a V-type twelve-cylinder engine, or a horizontally opposed six-cylinder engine.

[0016] An intake manifold 21 for introducing air into the combustion chamber of the engine 2 is provided at the intake port of the engine 2. The intake manifold 21 is connected to an intake pipe 22 for sucking outside air. That is, the intake manifold 21 communicates the intake pipe 22 with the intake ports of the respective cylinders of the engine 2.

[0017] The intake pipe 22 is provided with a water-cooled intercooler 23 for cooling the intake air of the engine 2, and a supercharger 24 for compressing the intake air and sending the compressed intake air to the intercooler 23 on the downstream side in the intake direction in which the intake air is sucked.

[0018] An intake air temperature sensor 31 for detecting the temperature of the intake air supplied from the intercooler 23 is provided on the downstream side in the intake direction of the intercooler 23 in the intake pipe 22.

[0019] An exhaust gas recirculation pipe 25 for returning a part of the exhaust gas of the engine 2 to the intake side is connected to the upstream side in the intake direction of the intake manifold 21 in the intake pipe 22. The exhaust gas recirculation pipe 25 is configured to perform EGR (Exhaust Gas Recirculation) for returning a part of the exhaust gas to the intake side. The exhaust gas recirculation pipe 25 is provided with a water-cooled EGR cooler 26 for cooling the exhaust gas to be returned.

[0020] An exhaust gas temperature sensor 32 for detecting the temperature of the exhaust gas returned from the EGR cooler 26 is provided on the downstream side in the recirculation direction, which is the direction in which the exhaust gas of the EGR cooler 26 is recirculated, of the exhaust gas recirculation pipe 25.

[0021] The engine 2 is provided with a gaseous fuel supply device 41 that supplies gaseous fuel to the intake port. A fuel supply pipe 42 that supplies fuel from a fuel container 45 to the gaseous fuel supply device 41 is connected to the gaseous fuel supply device 41.

[0022] On the downstream side of the fuel container 45 in the supply direction, which is the direction in which the gaseous fuel of the fuel supply pipe 42 is supplied, a pressure regulator 44 as a pressure reducing section and an oil filter 43 are provided in this order.

[0023] The oil filter 43 captures the oil contained in the gaseous fuel passing through. The pressure regulator 44 reduces the pressure of the gaseous fuel supplied from the fuel container 45. This pressure regulator 44 operates so that gaseous fuel at a specified pressure is supplied to the gaseous fuel supply device 41. A temperature sensor 33 that detects the temperature of the pressure regulator 44 is provided in the pressure regulator 44.

[0024] The gaseous fuel supply device 41 stores the gaseous fuel supplied from the pressure regulator 44 while maintaining its pressure.

[0025] When the pressure regulator 44 reduces the pressure of the gaseous fuel, the temperature drops due to adiabatic expansion. Therefore, if adiabatic expansion is performed for a long time, the temperature drops too much, causing freezing or the like, and proper pressure regulation cannot be achieved.

[0026] For this reason, the cooling water of the engine 2 is circulated around the pressure regulator 44 to prevent the temperature of the pressure regulator 44 from dropping.

[0027] Between the engine 2 and the pressure regulator 44, a first cooling path C1 is provided through which the cooling water of the engine 2 passes from the engine 2 around the pressure regulator 44 and returns to the engine 2.

[0028] On the upstream side of the first cooling path C1 in the direction in which the cooling water of the pressure regulator 44 flows, a first flow rate adjustment unit 51 for adjusting the flow rate of the cooling water flowing into the pressure regulator 44 is provided. The first flow rate adjustment unit 51 is constituted by, for example, a valve or a variable flow rate pump.

[0029] In this embodiment, the cooling water of the intercooler 23 and the EGR cooler 26 is also routed around the pressure regulator 44, and the cooling water of the intercooler 23 and the EGR cooler 26 is cooled by the temperature of the pressure regulator 44.

[0030] Between the engine 2 and the intercooler 23 and the EGR cooler 26, a second cooling path C2 is provided in which the cooling water discharged from the intercooler 23 and the EGR cooler 26 merges, passes around the pressure regulator 44, and branches back to the intercooler 23 and the EGR cooler 26.

[0031] Between the second cooling path C2 and the branch points to the pressure regulator 44 and the intercooler 23 and the EGR cooler 26, a second flow rate adjustment unit 52 for adjusting the flow rate of the cooling water flowing into the intercooler 23 and the EGR cooler 26 is provided. The second flow rate adjustment unit 52 is constituted by, for example, a valve or a variable flow rate pump.

[0032] The control unit 3 is constituted by a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data and the like, an input port, and an output port.

[0033] In the ROM of this computer unit, a program for causing the computer unit to function as the control unit 3 is stored together with various constants and various maps.

[0034] That is, when the CPU executes the program stored in the ROM using the RAM as a working area, this computer unit functions as the control unit 3 in the present embodiment.

[0035] Various sensors such as the intake air temperature sensor 31, exhaust gas temperature sensor 32, temperature sensor 33, knock sensor 34, etc. described above are connected to the input port of the control unit 3.

[0036] Various control objects such as the aforementioned first flow rate adjustment unit 51, second flow rate adjustment unit 52, etc. are connected to the output port of the control unit 3.

[0037] In the present embodiment, when the temperature of the pressure regulator 44 is higher than a predetermined pressure regulator limit temperature, knocking is detected by the knock sensor 34, and the temperature of the air supplied from the intercooler 23 to the engine 2 is higher than a predetermined temperature, the control unit 3 reduces the flow rate of the cooling water in the first cooling path C1 by the first flow rate adjustment unit 51 and increases the flow rate of the cooling water in the second cooling path C2 by the second flow rate adjustment unit 52.

[0038] The pressure regulator limit temperature is, for example, the design guaranteed temperature of the pressure regulator 44, and is a temperature at which the performance of the pressure regulator 44 can be guaranteed.

[0039] Also, when the temperature of the pressure regulator 44 is higher than a predetermined pressure regulator limit temperature, knocking is detected by the knock sensor 34, it is in exhaust gas recirculation, and the temperature of the exhaust gas supplied from the EGR cooler 26 to the engine 2 is higher than a predetermined temperature, the control unit 3 reduces the flow rate of the cooling water in the first cooling path C1 by the first flow rate adjustment unit 51 and increases the flow rate of the cooling water in the second cooling path C2 by the second flow rate adjustment unit 52.

[0040] Regarding the intercooler cooling control process by the control device for an internal combustion engine according to this embodiment configured as described above, it will be described with reference to FIG. 2. Note that the intercooler cooling control process described below starts when the control unit 3 starts operating and is executed at a preset time interval.

[0041] In step S1, the control unit 3 determines whether the actual temperature of the pressure regulator 44 is higher than a predetermined pressure regulator limit temperature.

[0042] If it is determined that the actual temperature of the pressure regulator 44 is higher than the pressure regulator limit temperature, the control unit 3 executes the process of step S2. If it is determined that the actual temperature of the pressure regulator 44 is not higher than the pressure regulator limit temperature, the control unit 3 executes the process of step S5.

[0043] In step S2, the control unit 3 determines whether knocking is detected by the knock sensor 34.

[0044] If it is determined that knocking is detected, the control unit 3 executes the process of step S3. If it is determined that knocking is not detected, the control unit 3 executes the process of step S5.

[0045] In step S3, the control unit 3 determines whether the intake air temperature, which is the temperature of the air supplied from the intercooler 23 to the engine 2, is higher than a predetermined temperature.

[0046] If it is determined that the intake air temperature is higher than the predetermined temperature, the control unit 3 executes the process of step S4. If it is determined that the intake air temperature is not higher than the predetermined temperature, the control unit 3 executes the process of step S5.

[0047] In step S4, the control unit 3 reduces the flow rate of the cooling water in the first cooling path C1 by the first flow rate adjustment unit 51, and increases the flow rate of the cooling water in the second cooling path C2 by the second flow rate adjustment unit 52. After executing the process of step S4, the control unit 3 ends the intercooler cooling control process.

[0048] In step S5, the control unit 3 opens the first flow rate adjustment unit 51 and closes the second flow rate adjustment unit 52. After executing the process of step S5, the control unit 3 ends the intercooler cooling control process.

[0049] Next, the EGR cooler cooling control process by the control device for the internal combustion engine according to the present embodiment will be described with reference to FIG. 3. Note that the EGR cooler cooling control process described below starts when the control unit 3 starts operating and is executed at a preset time interval.

[0050] In step S11, the control unit 3 determines whether the actual temperature of the pressure regulator 44 is higher than a predetermined pressure regulator limit temperature.

[0051] When it is determined that the actual temperature of the pressure regulator 44 is higher than the pressure regulator limit temperature, the control unit 3 executes the process of step S12. When it is determined that the actual temperature of the pressure regulator 44 is not higher than the pressure regulator limit temperature, the control unit 3 executes the process of step S16.

[0052] In step S12, the control unit 3 determines whether knocking is detected by the knock sensor 34.

[0053] When it is determined that knocking is detected, the control unit 3 executes the process of step S13. When it is determined that knocking is not detected, the control unit 3 executes the process of step S16.

[0054] In step S13, the control unit 3 determines whether or not the engine 2 is in the exhaust gas recirculation state where the exhaust gas is recirculated through the exhaust gas recirculation pipe 25.

[0055] If it is determined that the engine is in the exhaust gas recirculation state, the control unit 3 executes the process of step S14. If it is determined that the engine is not in the exhaust gas recirculation state, the control unit 3 executes the process of step S16.

[0056] In step S14, the control unit 3 determines whether or not the exhaust gas temperature, which is the temperature of the exhaust gas supplied from the EGR cooler 26 to the engine 2, is higher than a predetermined temperature.

[0057] If it is determined that the exhaust gas temperature is higher than the predetermined temperature, the control unit 3 executes the process of step S15. If it is determined that the exhaust gas temperature is not higher than the predetermined temperature, the control unit 3 executes the process of step S16.

[0058] In step S15, the control unit 3 reduces the flow rate of the cooling water in the first cooling path C1 by the first flow rate adjustment unit 51 and increases the flow rate of the cooling water in the second cooling path C2 by the second flow rate adjustment unit 52. After executing the process of step S15, the control unit 3 ends the EGR cooler cooling control process.

[0059] In step S16, the control unit 3 sets the first flow rate adjustment unit 51 as an open valve and sets the second flow rate adjustment unit 52 as a closed valve or a slightly open valve. After executing the process of step S16, the control unit 3 ends the EGR cooler cooling control process.

[0060] As described above, in this embodiment, when the temperature of the pressure regulator 44 is higher than a predetermined pressure regulator limit temperature, knocking is detected by the knock sensor 34, and the temperature of the air supplied from the intercooler 23 to the engine 2 is higher than a predetermined temperature, the control unit 3 reduces the flow rate of the cooling water in the first cooling path C1 by the first flow rate adjustment unit 51 and increases the flow rate of the cooling water in the second cooling path C2 by the second flow rate adjustment unit 52.

[0061] If the temperature of the pressure regulator 44 is higher than a predetermined pressure regulator limit temperature, there is room to lower the temperature of the pressure regulator 44 while preventing the pressure regulator 44 from freezing.

[0062] Under such circumstances, if knocking of the engine 2 is detected and the intake air temperature supplied to the engine 2 is higher than a predetermined temperature, the amount of cooling water supplied to the pressure regulator 44 by the first flow rate adjustment unit 51 is decreased to lower the temperature of the pressure regulator 44, while the amount of cooling water supplied to the intercooler 23 by the second flow rate adjustment unit 52 is increased.

[0063] Therefore, the cooling water with a lower temperature than that in the first cooling path C1 can be supplied to the intercooler 23 through the second cooling path C2, and the intake air temperature can be lowered to eliminate knocking. Compared with the method of retarding the ignition timing to eliminate knocking, the output performance can be improved.

[0064] Further, when the temperature of the pressure regulator 44 is higher than a predetermined pressure regulator limit temperature, the occurrence of knocking is detected by the knock sensor 34, the engine is in the exhaust gas recirculation state, and the temperature of the exhaust gas supplied from the EGR cooler 26 to the engine 2 is higher than a predetermined temperature, the first flow rate adjustment unit 51 reduces the flow rate of the cooling water in the first cooling path C1, and the second flow rate adjustment unit 52 increases the flow rate of the cooling water in the second cooling path C2.

[0065] If the temperature of the pressure regulator 44 is higher than a predetermined pressure regulator limit temperature, there is room to lower the temperature of the pressure regulator 44 while preventing the pressure regulator 44 from freezing.

[0066] Under such circumstances, when knocking of engine 2 is detected and the temperature of the exhaust gas supplied to engine 2 is higher than a predetermined temperature, the first flow rate adjustment unit 51 reduces the amount of cooling water supplied to the pressure regulator 44 to lower the temperature of the pressure regulator 44, while the second flow rate adjustment unit 52 increases the amount of cooling water supplied to the EGR cooler 26.

[0067] Therefore, the cooling water with a lower temperature from the first cooling path C1 can be supplied to the EGR cooler 26 through the second cooling path C2, so that the temperature of the intake air mixed with the exhaust gas can be reduced and knocking can be eliminated. Compared with the method of eliminating knocking by retarding the ignition timing, the output performance can be improved.

[0068] In this embodiment, an example has been described in which the control unit 3 makes various determinations and calculations based on various sensor information. However, the present invention is not limited to this. The vehicle 1 is provided with a communication unit capable of communicating with an off-vehicle device such as an external server, and various determinations and calculations are made by the off-vehicle device based on the detection information of various sensors transmitted from the communication unit. The determination result and calculation result are received by the communication unit, and various controls are performed using the received determination result and calculation result.

[0069] Although embodiments of the present invention have been disclosed, it is obvious that those skilled in the art can make changes without departing from the scope of the present invention. It is intended that all such modifications and equivalents be included in the following claims.

Explanation of Reference Numerals

[0070] 1 Vehicle 2 Engine (Internal Combustion Engine) 3 Control Unit 23 Intercooler 26 EGR Cooler 31 Intake Air Temperature Sensor 32 Exhaust Gas Temperature Sensor 33 Temperature Sensor 34 Knock Sensor (Knocking Detection Unit) 41 Gas Fuel Supply Device 44 Pressure regulator (pressure reducing section) 51 First flow rate adjusting section 52 Second flow rate adjusting section C1 First cooling path C2 Second cooling path

Claims

1. A gas fuel supply device that supplies gaseous fuel to an intake port of an internal combustion engine, A pressure reducing unit that reduces the pressure of the compressed gaseous fuel and supplies it to the gas fuel supply device, A first cooling path that supplies cooling water of the internal combustion engine to the pressure reducing unit, A water-cooled intercooler that cools the air inhaled into the internal combustion engine, A control device for an internal combustion engine, comprising a knocking detection unit that detects knocking of the internal combustion engine, wherein A second cooling path that is independent of the first cooling path and circulates cooling water between the pressure reducing unit and the intercooler, A first flow rate adjustment unit that adjusts the flow rate of the cooling water in the first cooling path, A second flow rate adjustment unit that adjusts the flow rate of the cooling water in the second cooling path, When the temperature of the pressure reducing unit is higher than a predetermined temperature, knocking is detected by the knocking detection unit, and the temperature of the air supplied from the intercooler to the internal combustion engine is higher than the predetermined temperature, the first flow rate adjustment unit reduces the amount of cooling water supplied to the pressure reducing unit, while the second flow rate adjustment unit increases the amount of cooling water supplied to the intercooler. A control device for an internal combustion engine comprising a control unit.

2. A gas fuel supply device that supplies gaseous fuel to an intake port of an internal combustion engine, A pressure reducing unit that reduces the pressure of the compressed gaseous fuel and supplies it to the gas fuel supply device, A first cooling path that supplies cooling water of the internal combustion engine to the pressure reducing unit, A water-cooled EGR cooler that cools the exhaust gas recirculated to the internal combustion engine, A control device for an internal combustion engine, comprising a knocking detection unit that detects knocking of the internal combustion engine, wherein A second cooling path that is independent of the first cooling path and circulates cooling water between the pressure reducing unit and the EGR cooler, A first flow rate adjustment unit that adjusts the flow rate of the cooling water in the first cooling path, A second flow rate adjustment unit that adjusts the flow rate of the cooling water in the second cooling path; A control unit of an internal combustion engine, comprising: when the temperature of the decompression unit is higher than a predetermined temperature, knocking is detected by the knocking detection unit, a part of the exhaust gas is refluxed to the internal combustion engine, and the temperature of the exhaust gas supplied from the EGR cooler to the internal combustion engine is higher than the predetermined temperature, while reducing the amount of cooling water supplied to the decompression unit by the first flow rate adjustment unit, increasing the amount of cooling water supplied to the EGR cooler by the second flow rate adjustment unit.

Images