Control device for internal combustion engine

Abstract

Control device (1) for an internal combustion engine (100), comprising: a fuel pressure control unit (90) configured to regulate the pressure of a fuel supplied to a fuel injector (134) configured to inject the fuel into an internal combustion engine (100), wherein the fuel injector (134) comprises a valve body, an actuating unit for actuating the valve body, and a fuel injection orifice which is opened or closed according to the actuating of the valve body, wherein a cylinder pressure sensor (140), configured to detect an internal cylinder pressure, which is a pressure in a combustion chamber of the internal combustion engine (100), is attached to the internal combustion engine (100), and wherein the fuel pressure control unit (90) is configured to control the fuel pressure based on a pressure difference between the cylinder internal pressure detected by the cylinder pressure sensor (140) before the valve body is separated from a valve seat and the cylinder internal pressure detected by the cylinder pressure sensor (140) when the valve body is separated from the valve seat.

Description

field of technology

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

[0002] To improve vehicle fuel efficiency in recent years, reducing vehicle power consumption has become essential. One way to achieve this is by reducing the pressure of the fuel being delivered from the fuel tank to the fuel injector. Specifically, the closing force of the fuel injector is determined by the sum of the elastic force exerted by an elastic body, such as a spring, which biases the injector's valve body in the closing direction, and the fuel pressure. Reducing the fuel pressure, therefore, reduces the power required to actuate the fuel injector, effectively lowering fuel consumption.Furthermore, reducing the valve closing force of the fuel injector can also reduce the inlet pressure or inlet friction of a fuel pump that delivers fuel from the fuel tank to the fuel injector, and a knocking noise generated at the time of valve closing.

[0003] However, if the fuel pressure is reduced too much, the oil tightness of the fuel injector decreases, raising concerns about possible fuel leaks.

[0004] Therefore, it is necessary to regulate the fuel pressure appropriately according to the valve closing force, so that the valve closing force does not fall below a valve closing force that ensures the oil tightness of the fuel injection valve.

[0005] From JP 2016-217180 A, a reduction of the control current during the opening and closing of a fuel injector is known. JP 2016-217180 A discloses a method for detecting a collision of a moving core, which is controlled during the opening and closing of the fuel injector, by means of a cylinder pressure sensor that detects a pressure in a cylinder in which the fuel injector is installed, and for reducing a control current according to a detection result.

[0006] From DE 10 2014 207 452 A1, a fuel injection valve is known which includes a cylinder pressure sensor located near its distal end. The cylinder pressure sensor detects the cylinder pressure in a cylinder and outputs a first sensor signal in response to the detected cylinder pressure. Furthermore, a signal processor, which performs predetermined signal processing with respect to the first sensor signal in order to convert the first sensor signal into a second sensor signal, is arranged between the cylinder pressure sensor and a solenoid unit located at a proximal end of the fuel injection valve. Brief description of the invention Technical task

[0007] According to the method disclosed in JP 2016-217180 A, it is possible to detect the opening or closing of the fuel injector. However, it is not possible to effectively regulate the pressure of a fuel according to the valve closing force of the fuel injector.

[0008] The present invention is therefore made taking into account the above-mentioned problems and one object of the present invention is to appropriately regulate the pressure of the fuel according to the valve closing force of the fuel injection valve. Technical solution

[0009] According to one aspect of the present invention, a control device for an internal combustion engine is provided, comprising: a fuel pressure control unit configured to regulate the pressure of a fuel supplied to a fuel injector configured to inject the fuel into an internal combustion engine, the fuel injector comprising a valve body, an actuating unit configured to actuate the valve body, and a fuel injection orifice that is opened or closed according to the actuation of the valve body, a cylinder pressure sensor configured to detect an internal cylinder pressure, which is a pressure in a combustion chamber of the internal combustion engine, being attached to the internal combustion engine, and the fuel pressure control unit being configured to regulate the fuel pressure based on a pressure difference between the internal cylinder pressure,the cylinder pressure measured by the cylinder pressure sensor before the valve body is separated from a valve seat, and the cylinder internal pressure measured by the cylinder pressure sensor when the valve body is separated from the valve seat. Advantageous effects of the invention

[0010] According to the present invention, the pressure of a fuel can be advantageously regulated according to a valve closing force of a fuel injection valve. Brief description of the drawings Fig. Figure 1 is a view illustrating the main configurations of an internal combustion engine and a control device for an internal combustion engine according to one embodiment. Fig. Figure 2 is a functional block diagram illustrating a functional design of the control device according to the embodiment. Fig. Figure 3 is a schematic representation of a main configuration of an internal combustion engine in which the control device is used. Fig. Figure 4 is a top view of an arrangement of cylinders. Fig. Figure 5 is a view illustrating a pressurization pump. Fig. Figure 6 is an example of a curve shape of a cylinder internal pressure detected by a cylinder pressure sensor. Fig. Figure 7 is an example of the curve shape of the cylinder internal pressure detected by the cylinder pressure sensor. Fig. Figure 8 is a cross-sectional view of a fuel injector and cylinder pressure sensor. Fig. Figure 9 is a view illustrating an example of curve shapes of a valve opening control signal and an output signal of the cylinder pressure sensor. Fig. Figure 10 is a flowchart illustrating a method for controlling fuel pressure according to the embodiment. Fig. Figure 11 is a schematic representation to illustrate a state of low fuel pressure requirement. Description of embodiments

[0011] The following describes a control device 1, which is an operating mode of a control device for an internal combustion engine according to an embodiment of the present invention. In this embodiment, the case is described by way of example where the control device 1 controls a 4-cylinder internal combustion engine 100.

[0012] In the following embodiment, a combination of some or all embodiments of the internal combustion engine 100 and some or all embodiments of the control device 1 is referred to as the control device 1 of the internal combustion engine 100. internal combustion engine

[0013] Fig. Figure 1 is a view illustrating the main configurations of the internal combustion engine 100 and the control device 1 controlling the internal combustion engine 100.

[0014] In the internal combustion engine 100, air drawn in from outside flows through an air filter 110, an intake pipe 111, and an intake manifold 112, and enters each cylinder 150. The amount of air flowing into each cylinder 150 is regulated by a throttle valve 113, and the air volume regulated by the throttle valve 113 is measured by a flow sensor 114. Furthermore, an intake pressure sensor 116, located in the intake manifold 112 (see Fig. 3) a pressure of the air flowing into each cylinder 150 was measured.

[0015] The throttle valve 113 is equipped with a throttle opening sensor 113a, which detects the opening of a throttle valve. The opening information of the throttle valve 113 detected by the throttle opening sensor 113a is output to the control device (electronic control unit: ECU) 1.

[0016] The throttle valve 113 is an electrically actuated electronic throttle valve. However, any valve can be used as long as the airflow rate can be appropriately regulated.

[0017] The temperature of a gas flowing into each cylinder 150 is measured by an intake air temperature sensor 115.

[0018] A crank angle sensor 121 is provided radially outside a toothed ring 120 attached to a crankshaft 123. The crank angle sensor 121 detects a rotation angle of the crankshaft 123. In this embodiment, the crank angle sensor 121 detects the rotation angle of the crankshaft 123, for example, every 10° and every combustion cycle.

[0019] A water temperature sensor 122 is provided in a water jacket (not shown) of the internal combustion engine 100. The water temperature sensor 122 detects the temperature of the cooling water of the internal combustion engine 100.

[0020] The vehicle also includes an accelerator pedal position sensor (APS) 126, which detects the amount of travel (actuation amount) of an accelerator pedal 125. The accelerator pedal position sensor 126 detects a torque requested by the driver. The driver's requested torque, detected by the accelerator pedal position sensor 126, is output to the control device 1, which will be described later. The control device 1 actuates the throttle valve 113 based on this requested torque.

[0021] Fuel stored in a fuel tank 130 is drawn in by a feed pump 131 and then passes through a fuel line 133 to a pressure pump 132. The pressure pump 132 pressurizes the fuel supplied by the feed pump 131 to regulate the fuel pressure to a predetermined level and sends the fuel via the fuel line 133 to a fuel injector 134 installed in each cylinder 150. As a result of the pressure adjustment by the pressure pump 132, excess fuel is returned to the fuel tank 130 via a return line (not shown).

[0022] The fuel injector 134 injects the fuel supplied by the pressure pump 132 into each cylinder 150. The fuel injector 134 is located in Fig. Although the fuel injector 134 is attached to the intake manifold 112, it is actually mounted on a cylinder head 180 of the internal combustion engine 100, allowing fuel to be injected into cylinder 150. The fuel line 133 between the pressurization pump 132 and the fuel injector 134 is equipped with a fuel pressure sensor 135 (see figure). Fig. 5), which measures the fuel injection pressure at the fuel injector 134.

[0023] A cylinder pressure sensor (CPS, also referred to as cylinder internal pressure sensor) 140 is provided in each cylinder 150 of the internal combustion engine 100. The cylinder pressure sensor 140 detects a pressure (combustion pressure) in the cylinder 150. In this embodiment, the cylinder pressure sensor 140 is provided at one tip of the fuel injector 134.

[0024] The cylinder pressure sensor 140 is a vibration detector type sensor that detects the combustion pressure by measuring mechanical vibrations of the internal combustion engine 100. In this embodiment, the cylinder pressure sensor 140 is a resonance-free vibration detection sensor and can detect vibrations of the internal combustion engine 100 over a wide frequency band.

[0025] Each cylinder 150 is equipped with an exhaust manifold 160, which carries exhaust gas from the cylinder 150 after combustion. A three-way catalyst 161 is provided on one exhaust side of the exhaust manifold 160, and exhaust gas from the cylinder 150 is carried to the exhaust manifold 160. The exhaust gas passes through the exhaust manifold 160, is cleaned by the three-way catalyst 161, and is then released into the atmosphere.

[0026] An upstream air-fuel ratio sensor 162 and an exhaust gas temperature sensor 164 are provided on the upstream side of the three-way catalytic converter 161. The upstream air-fuel ratio sensor 162 continuously detects the air-fuel ratio of the exhaust gas discharged from each cylinder 150. The exhaust gas temperature sensor 164 measures the temperature of the exhaust gas discharged from the cylinder 150.

[0027] Furthermore, an air-fuel ratio sensor 163 is provided downstream on the outflow side of the three-way catalyst 161. The downstream air-fuel ratio sensor 163 outputs a switch-like detection signal in the near range of a theoretical air-fuel ratio. In this embodiment, the downstream air-fuel ratio sensor 163 is, for example, an O2 sensor.

[0028] Furthermore, a spark plug 200 is provided in an upper section of each cylinder 150. Due to the discharge (ignition) of the spark plug 200, a spark is ignited in a mixture of air and fuel in cylinder 150, an explosion occurs in cylinder 150, and a piston 170 is forced downwards. When the piston 170 is forced downwards, the crankshaft 123 rotates.

[0029] An ignition coil 300, which generates electrical energy (voltage) supplied to the spark plug 200, is connected to the spark plug 200. The discharge is generated between a middle electrode and an outer electrode of the spark plug 200 by a voltage generated in the ignition coil 300.

[0030] Output signals from various sensors described above, such as the throttle opening sensor 113a, the flow rate sensor 114, the crankshaft angle sensor 121, the accelerator pedal position sensor 126, the water temperature sensor 122, the fuel pressure sensor 135, the cylinder pressure sensor 140, or the like, are sent to the control device 1. The control device 1 detects the operating state of the internal combustion engine 100 based on the output signals from the various sensors and controls the amount of air (target air quantity) sent to the cylinder 150 (target air quantity), the amount of fuel injected, the ignition timing of the spark plug 200, the amount of fuel pressurized by the pressurization pump 132, or the like.

[0031] The target air quantity calculated by the control device 1 is converted into an electronic throttle control signal based on the throttle opening (target throttle opening) and output to an electric motor (not shown) which operates the throttle valve 113. In addition, the ignition timing calculated by the control device 1 is output to the ignition coil 300 as an ignition signal converted into an excitation start angle and an excitation angle, and the fuel is discharged (ignited) by the spark plug 200 based on this ignition signal. Hardware design of the control device

[0032] Next, the overall hardware design of control device 1 will be described.

[0033] As in Fig. As shown in Figure 1, the control device 1 comprises an analog input unit 10, a digital input unit 20, an analog-to-digital (A / D) converter 30, a random access memory (RAM) 40 and a microprocessor unit (MPU) 50, a read-only memory (ROM) 60, an input / output (I / O) port 70 and an output circuit 80.

[0034] Analog output signals from various sensors, such as the throttle opening sensor 113a, the flow rate sensor 114, the accelerator pedal position sensor 126, the upstream air-fuel ratio sensor 162, the downstream air-fuel ratio sensor 163, the cylinder pressure sensor 140, the water temperature sensor 122 and the fuel pressure sensor 135, are input into the analog input unit 10.

[0035] The A / D converter 30 is connected to the analog input unit 10. The analog output signals from the various sensors, which are input to the analog input unit 10, undergo signal processing such as noise reduction, are converted into digital signals by the A / D converter 30, and stored in the RAM 40.

[0036] The digital output signal from the crank angle sensor 121 is entered into the digital input unit 20.

[0037] An I / O port 70 is connected to the digital input unit 20, and the digital output signal input into the digital input unit 20 is stored in RAM 40 via the I / O port 70.

[0038] Each output signal stored in RAM 40 is processed arithmetically by the MPU 50.

[0039] The MPU 50 executes a control program (not shown) stored in ROM 60 to arithmetically process the output signal stored in RAM 40 according to a control program. The MPU 50 calculates a control value that defines an actuation amount for each actuator controlling the internal combustion engine 100 according to the control program (for example, the throttle valve 113, the pressurization pump 132, the spark plug 200, and so on), and temporarily stores the control value in RAM 40.

[0040] The control value, which is stored in RAM 40 and defines the actuation amount of the actuator, is output to the output circuit 80 via the I / O port 70.

[0041] Each function of a fuel injection control unit 82 (see Fig. 2), which controls the fuel injector 134, an ignition control unit 83 (see Fig. 2), which controls a voltage applied to the spark plug 200, and a fuel pressure control unit 90 (see Fig. 2), which controls the pressure pump 132, is provided in the output circuit 80. Functional block of the control device

[0042] A functional design of the control device 1 according to the embodiment is now described.

[0043] Fig. Figure 2 is a functional block diagram illustrating the functional design of the control device 1 according to the embodiment. For example, each function of the control device 1 is implemented by the output circuit 50 when the MPU 50 executes the control program stored in the ROM 60.

[0044] As in Fig. As shown in Figure 2, the output circuit 80 of the control device 1 according to the embodiment comprises a total control unit 81, the fuel injection control unit 82, the ignition control unit 83 and the fuel pressure control unit 90.

[0045] The overall control unit 81 is connected to the accelerator pedal position sensor 126 and the cylinder pressure sensor 140 (CPS) and receives a requested torque (acceleration signal S1) from the accelerator pedal position sensor 126 and an output signal S2 from the cylinder pressure sensor 140.

[0046] The overall control unit 81 controls the fuel injection control unit 82, the ignition control unit 83 and the fuel pressure control unit 90 as a whole on the basis of the requested torque (acceleration signal S1) from the accelerator pedal position sensor 126 and the output signal S2 from the cylinder pressure sensor 140.

[0047] In this embodiment, at least information about the combustion pressure (oscillation: output signal S2) from the cylinder pressure sensor 140 is entered into the overall control unit 81, and the overall control unit 81 detects the combustion pressure or a knocking event based on this information.

[0048] The fuel injection control unit 82 is connected to a cylinder determination unit 84, which determines each cylinder 150 of the internal combustion engine 100, an angle information generation unit 85, which measures a crank angle of the crankshaft 123, and a speed information generation unit 86, which measures an engine speed, and receives cylinder differentiation information S3 from the cylinder determination unit 84, crank angle information S4 from the angle information generation unit 85, and engine speed information S5 from the speed information generation unit 86.

[0049] The fuel injection control unit 82 is further connected to an intake air quantity measuring unit 87, which measures an intake quantity of air drawn into the cylinder 150, a load information generation unit 88, which measures an engine load, and a water temperature measuring unit 89, which measures a temperature of engine coolant, and receives intake air quantity information S6 from the intake air quantity measuring unit 87, engine load information S7 from the load information generation unit 88 and coolant temperature information S8 from the water temperature measuring unit 89.

[0050] The fuel injection control unit 82 calculates, based on the received information, an injection quantity and injection time of the fuel to be injected from the fuel injector 134 and outputs a valve opening control signal S9 to control the fuel injector 134 based on the calculated fuel injection quantity and injection time.

[0051] Apart from the overall control unit 81, the ignition control unit 83 is connected to the cylinder determination unit 84, the angle information generation unit 85, the speed information generation unit 86, the load information generation unit 88 and the water temperature measurement unit 89 and receives the respective information from these.

[0052] Based on the received information, the ignition control unit 83 calculates a current quantity (excitation angle) for exciting a primary coil (not shown) of the ignition coil 300, a start time of the excitation and a time (ignition time) at which the current for exciting the primary coil is switched off.

[0053] The ignition control unit 83 outputs an ignition signal SA to the primary coil of the ignition coil 300 based on the calculated excitation angle, the calculated excitation start time and the calculated ignition time, in order to carry out discharge control (ignition control) via the spark plug 200.

[0054] In addition, combustion pressure information (cylinder internal pressure information) and knock information from the overall control unit 81 are entered into the ignition control unit 83.

[0055] The ignition control unit 83 calculates an ignition timing correction value via MBT control based on the combustion pressure information and a retard angle correction value based on the knock information. Upon the occurrence of a knock event, the ignition control unit 83 executes either MBT control (minimum advance for the best torque) or retard angle control based on these calculation results.

[0056] The fuel pressure control unit 90 is connected to the overall control unit 81 and to a fuel pressure measuring unit 91, which measures the fuel pressure, and receives the combustion pressure information (cylinder internal pressure information) from the overall control unit 81 and fuel pressure information S10 from the fuel pressure measuring unit 91.

[0057] The fuel pressure control unit 90 calculates the pressure of the fuel injected from the fuel injector 134 based on the respective information received and outputs fuel pressure control information S11 to the pressure pump 132 to control the pressure of the fuel supplied to the fuel injector 134.

[0058] Furthermore, the fuel pressure calculated by the fuel pressure control unit 90 is output to the fuel injection control unit 82. A fuel pressure calculation result output by the fuel pressure control unit 90 to the fuel injection control unit 82 is used to control the fuel injector 134 in the fuel injection control unit 82. Main designs of the internal combustion engine

[0059] The following is a description of a main embodiment of the internal combustion engine 100, in which the control device 1 is used according to the embodiment. The internal combustion engine 100 is, for example, a gasoline engine for vehicles with in-cylinder injection.

[0060] Fig. Figure 3 is a schematic representation of the main design of the internal combustion engine 100, in which the control device 1 is used. Fig. Figure 4 is a top view to illustrate an arrangement of the respective cylinder 150.

[0061] Referring to Fig. 3 describes by way of example a case in which the internal combustion engine 100 of the embodiment is a 4-cylinder in-line gasoline engine for a vehicle in which combustion is realized by spark ignition.

[0062] As in Fig. 3 and Fig. As illustrated in Figure 4, the internal combustion engine 100 has a first cylinder 151, a second cylinder 152, a third cylinder 153, and a fourth cylinder 154 arranged in a line with a cylinder block (not shown). Unless otherwise specified, the first cylinder 151 through the fourth cylinder 154 will be referred to simply as cylinder 150 in the following.

[0063] As in Fig. 3 and Fig. As shown in Figure 4, the spark plug 200 and the cylinder pressure sensor 140 are mounted on the inside of the combustion chamber 150a of each cylinder 150. In the combustion chamber 150a of each cylinder 150, the rotation angle of the crankshaft 123 has a cycle of 180°, and ignition and combustion are carried out by the spark plug 200. If the internal combustion engine 100 has a four-cylinder bank, combustion in each cylinder 150 is carried out in the sequence: first cylinder 151, third cylinder 153, fourth cylinder 154, and second cylinder 152.

[0064] As in Fig. As shown in Figure 3, a cylinder head 180 is provided above each cylinder 150. An intake camshaft 5a, which actuates an intake valve 6a that regulates the intake of the air-fuel mixture (mixture of air and fuel) into the cylinder 150, and an exhaust camshaft 5b, which actuates an exhaust valve 6b that regulates the expulsion of exhaust gas from the inside of the cylinder 150, are provided in the cylinder head 180.

[0065] As in Fig. As shown in Figure 3, high-pressure fuel supplied by the pressure pump 132 is routed via the fuel line 133 to the fuel injector 134 attached to each cylinder 150 and is injected from the fuel injector 134 into each cylinder 150. Pressurization pump

[0066] The pressure pump 132, which supplies high-pressure fuel to the fuel injection valve 134, is now described.

[0067] Fig. Figure 5 is a view illustrating the pressure pump 132.

[0068] As in Fig. As shown in Figure 5, the pressurization pump 132 is connected via the fuel line 133 to the fuel pump 131 installed in the fuel tank 130, or to the fuel injector 134. The pressurization pump 132 is connected to a pump control cam 500, which is driven by the crankshaft 123 of the internal combustion engine 100, and is actuated by the rotary drive of the pump control cam 500. As a result, low-pressure fuel supplied by the fuel pump 131 is pressurized, and after pressurization, high-pressure fuel is sent to the fuel injector 134.

[0069] The pressurization pump 132 comprises a suction valve 1321, a pressurization chamber 1322, a plunger piston 1323, a tappet 1324, a compression spring 1325, and a discharge valve 1326. The plunger piston 1323 is pressed against the pump control cam 500 via the tappet 1324 by an elastic force exerted by the compression spring 1325. The pump control cam 500 has a rectangular cross-sectional shape and is driven by the crankshaft 123 of the internal combustion engine 100. The volume of the pressurization chamber 1322 changes when the plunger piston 1323 is moved up and down in accordance with the rotary drive of the pump control cam 500.

[0070] The fuel drawn from the fuel tank 130 by the feed pump 131 is transported via a Fig. The path shown in Figure 5 with arrows leads to the pressurization pump 132. The pressurization pump 132 opens the suction valve 1321 to introduce the fuel into the pressurization chamber 1322 and then closes the suction valve 1321 at a predetermined time. In this state, the plunger piston 1323 is raised according to the rotary drive of the pump control cam 500, the volume of the pressurization chamber 1322 decreases, and thus the fuel pressure in the pressurization chamber 1322 increases.

[0071] The pressurization pump 132 opens the discharge valve 1326 at a time when the pressurization chamber 1322 reaches a predetermined setpoint. Accordingly, the high-pressure fuel pressurized by the pressurization pump 132 is sent to the fuel line 133 on the side of the fuel injector 134 and, via a common pressure line 1331 to which the multiple fuel injectors 134 are attached, to each fuel injector 134.

[0072] A pressurization step of the pressurization pump 132 is a process from the closing of the suction valve 1311 until the opening of the discharge valve 1326. During this period, a drive torque of the pump control cam 500 is required to lift the plunger piston 1323 via the rotary drive of the pump control cam 500. Since the pump control cam 500 is interlocked with the crankshaft 123 of the internal combustion engine 100, the drive torque of the pump control cam 500 for actuating the pressurization pump 132 becomes a reaction force against a combustion torque (engine torque) generated by the combustion of the internal combustion engine 100. The sum of the drive torque of the pump control cam 500 and the combustion torque is transmitted externally as engine torque of the internal combustion engine 100.

[0073] In this embodiment, the pump control cam 500 rotates once (360°) for every two rotations (720°) of the crankshaft 123. Thus, each time the crankshaft 123 completes half a rotation (180°), the drive torque of the pump control cam 500 acts as a load on the crankshaft 123.

[0074] In this embodiment, the pump control cam 500 has a fundamentally rectangular shape in cross-sectional view; however, the shape of the pump control cam 500 can be expediently determined according to the number of cylinders of the internal combustion engine 100. In this case, it is desirable that the number of vertices (for example, four vertices of a quadrilateral) of the pump control cam 500 is equal to the number of cylinders. For example, in the case of a 6-cylinder internal combustion engine, two triangular pump control cams 500 can be used, and the total number of vertices of the pump control cams 500 can correspond to the number of cylinders. Furthermore, in the case of an 8-cylinder internal combustion engine, two square pump control cams 500 can be used, and the total number of vertices of the pump control cams 500 can correspond to the number of cylinders.

[0075] In this embodiment, the control device 1 also controls the suction valve 1321 of the pressurizing pump 132 such that the suction valve 1321 closes when the position of the piston 170 in the cylinder 150 exceeds top dead center. The mounting position of the pump control cam 500 around a rotating shaft is set such that the plunger piston 1323 is actuated upwards after the piston 170 passes top dead center. Therefore, the drive torque of the pump control cam 500 reaches its maximum value after the piston 170 passes top dead center. Change in cylinder internal pressure

[0076] Now, a change in the cylinder internal pressure (combustion pressure) P in cylinder 150 depending on the combustion state in the internal combustion engine 100 is described.

[0077] Fig. 6 and Fig. Figure 7 illustrates examples of curve shapes for the cylinder internal pressure measured by the cylinder pressure sensor 140. One curve shape, P11, in Fig. Figure 6 shows an example of a change in cylinder pressure P during normal combustion. A curve shape P12 in Fig. Figure 7 shows an example of a change in the cylinder internal pressure P during a flame extinguishing state. Fig. 6 and Fig. Figure 7 shows a horizontal axis representing time and a vertical axis representing the cylinder internal pressure P.

[0078] As in curve shape P11 of Fig. As shown in Figure 6, the cylinder pressure P of cylinder 150 reaches a maximum value after top dead center during normal combustion. However, as shown in curve P12 of Fig. As shown in Figure 7, the maximum cylinder pressure P of cylinder 150 is lower in the flame-extinguishing condition than in the normal combustion condition, and the time at which the maximum value is reached is closer to top dead center. The flame-extinguishing condition is a state in which combustion starts after ignition while the air-fuel mixture in cylinder 150 is lean, and flame extinguishing then occurs during combustion. Fuel injector and cylinder pressure sensor

[0079] Now the fuel injector 134 and the cylinder pressure sensor 140 will be described.

[0080] Fig. Figure 8 is a cross-sectional view of the fuel injector 134 and the cylinder pressure sensor 140. Fig. Figure 8 shows a structure of an axial cross-section of the fuel injection valve 134, which is inserted into the cylinder head 180 from the outside of the internal combustion engine 100 towards the inside of each cylinder 150 and at the tip of which the cylinder pressure sensor 140 is arranged, in a tubular fuel injection valve 134, which is inserted into the cylinder head 180 from the outside of the internal combustion engine 100 towards the inside of each cylinder 150 and at the tip of which the cylinder pressure sensor 140 is arranged, and which is cut along a central axis extending in the insertion direction.

[0081] The fuel injector 134 comprises a nozzle holder 1342, a core 1343, a housing 1344, a nozzle body 1345, a nozzle needle 1346, an armature 1347, an upstream needle guide 1348, an downstream needle guide 1349, a spring 1351, a regulating pin 1352 and a solenoid 1353.

[0082] The nozzle holder 1342 accommodates the nozzle body 1345, the nozzle needle 1346, the armature 1347, the upstream needle guide 1348, and the downstream needle guide 1349, securing them in their respective positions. The core 1343 accommodates the spring 1351 and the regulating bolt 1352, securing them in their respective positions. The housing 1344 accommodates the solenoid coil 1353.

[0083] As in Fig. As shown in Figure 8, the fuel injector 134 is attached to the cylinder head 180 via a tolerance ring 1341. The tolerance ring 1341 abuts a seat surface of the cylinder head 180 and absorbs an off-center load when the fuel injector 134 is installed at an angle to the cylinder head 180.

[0084] A common rail 1331 (see Fig. 5) is located on the opposite side of cylinder 150. The fuel injector 134 is inserted into a mounting hole provided in the common pressure line 1331 via the O-ring 1354. When the O-ring 1354 comes into contact with an inner edge section of the mounting hole of the common pressure line 1331, an inner and an outer space of the mounting hole are sealed.

[0085] The support ring 1355 supports the O-ring 1354 on an upper end face of the core 103.

[0086] A high-pressure fuel from the common pressure line 1331 flows into the fuel injector 134 in a state in which foreign matter is removed by a filter 1356 attached to an upper end of the fuel injector 134, flows through a fuel channel formed in the fuel injector 134, and then reaches the nozzle body 1345. Several fuel injection holes are formed in the nozzle body 1345, and the fuel is dispensed from the fuel injection holes into the cylinder 150 in a single operating cycle by the nozzle needle 1346, which serves as the valve body.

[0087] The nozzle needle 1346 is held in the nozzle holder 1342 in a position in which it is axially displaceable via the armature 1347. An outer edge of the nozzle needle 1346 is supported by a flow-side needle guide 1348 attached to the nozzle holder 1342 and a flow-side needle guide 1349 attached to the nozzle body 1345. A ring seal 1350 is attached to an outer edge section on the flow side of the nozzle holder 1342 and thus seals an inner and an outer space of the cylinder head 180.

[0088] The spring 1351 is arranged between the nozzle needle 1346 and the regulating pin 1352. The regulating pin 1352 clamps one layer of an upper end section of the spring 1351. When the spring 1351 presses the nozzle needle 1346 against a seat section of the nozzle body 1345, the fuel injector 134 is closed. At this point, the nozzle needle 1346 acts as the valve body and the seat section of the nozzle body 1345 acts as the valve seat.

[0089] The magnetic coil 1353 is arranged radially outside the armature 1347. The magnetic coil 1353 is energized via a wire 1357 by a control current from a control circuit (not shown) located outside the fuel injection valve 134. Accordingly, the core 1343 is energized, generating a magnetic attraction, and the armature 1347 is pulled upwards in the axial direction. Simultaneously, a convex section on an outer diameter side of the nozzle needle 1346 engages the armature 1347, thus pulling the nozzle needle 1346 upwards in the axial direction and separating it from the seat area of ​​the nozzle body 1345. This opens several fuel injection holes formed in the nozzle body 1345, and the high-pressure fuel supplied by the pressurization pump 132 via the common pressure line 1331 is injected into the cylinder 150.This means that the solenoid coil 1353 serves as a control unit for the nozzle needle 1346, which is the valve body. The fuel injection valve 134 is actuated by the fact that, according to the control signal of the nozzle needle 1346 by the solenoid coil 1353, the fuel injection orifice of the nozzle body 1345 is opened or closed.

[0090] The cylinder pressure sensor 140 is provided at the tip of the nozzle holder 1342 of the fuel injector 134 and has a diaphragm 1411 and a pressure sensing element 1412.

[0091] When the fuel injector 134 is inserted into the cylinder head 180, the diaphragm 1411 of the cylinder pressure sensor 140 is positioned closer to the combustion chamber of cylinder 150 than the fuel injection orifice formed in the nozzle body 1345 of the fuel injector 134. Due to this arrangement, the diaphragm 1411 is bent and deformed according to the pressure (internal cylinder pressure) in cylinder 150, thus acting as a pressure-sensing unit. A deformation of the diaphragm 1411 corresponding to the internal cylinder pressure is detected by the pressure sensing element 1412 arranged around the diaphragm 1411, and the pressure sensing element 1412 outputs an electrical signal corresponding to this deformation. In other words, the pressure sensing element 1412 acts as a pressure sensing unit that detects the pressure detected by the diaphragm 1411 as the internal cylinder pressure.The pressure sensing element 1412, for example, is formed by a piezoelectric element. Accordingly, it is possible to detect the internal cylinder pressure (combustion pressure) of the cylinder 150 over a wide temperature range.

[0092] The electrical signal from the pressure sensing element 1412 is sent via a wire 1413 to a charge amplifier 1414, which is integrally formed with the fuel injection valve 134. The charge amplifier 1414 integrates the electrical signal from the pressure sensing element 1412 and generates the output signal S2 corresponding to the order of magnitude of the cylinder internal pressure. The output signal S2 from the charge amplifier 1414 is connected via a terminal 1415 to the analog input unit 10 (see figure). Fig. 1) sent to the control device 1. The terminal 1415 and the wire 1413, together with the wire 1357 described above, are integrally encapsulated with synthetic resin for the excitation of the solenoid coil 1353 with the control current.

[0093] To reduce noise, the charge amplifier 1414 is preferably arranged as close as possible to the pressure sensing element 1412. Alternatively, the charge amplifier 1414 can be omitted by replacing its integration function with the processor in the control device 1, thus reducing costs. Methods for controlling fuel pressure

[0094] A method for controlling the fuel pressure according to the embodiment is now described.

[0095] Fig. Figure 9 is a view illustrating an example of curve shapes of the valve opening control signal S9 output by the fuel injection control unit 82 to the fuel injection valve 134 and the output signal S2 from the cylinder pressure sensor 140.

[0096] As in Fig. As shown in Figure 9, the output signal S2 of the cylinder pressure sensor 140 is modified according to the valve opening control signal S9. That is, when an excitation pulse of the valve opening control signal S9 is activated at time t1, a valve opening instruction is sent to the fuel injector 134, and fuel injection begins. At this time, the nozzle needle 1346 is pulled upwards axially by the solenoid coil 1353, as described above. When the nozzle needle 1346 reaches a predetermined stroke height, the armature 1347 and the core 1343 collide. A mechanical vibration generated in the fuel injector 134 as a result of this collision is transmitted to the cylinder pressure sensor 140 and detected by the cylinder pressure sensor 140 as a change in the cylinder's internal pressure. As shown in Figure 9, the output signal S2 of the cylinder pressure sensor 140 is modified when the valve opening control signal S9 is activated at time t1. Fig. As shown in Figure 9, there is therefore a fluctuation in the amplitude of the output signal S2 of the cylinder pressure sensor 140 after time t1.

[0097] Furthermore, if the excitation pulse of the valve opening control signal S9 is switched off at time t2, a valve closing instruction is sent to the fuel injector 134 and fuel injection is terminated. In this case, with the switch-off of a control current to the solenoid coil 1353, the nozzle needle 1346 is pushed back by the spring 1351 and the nozzle needle 1346 collides with the seat area of ​​the nozzle body 1345. The mechanical vibration generated in the fuel injector 1344 due to this collision is also transmitted to the cylinder pressure sensor 140 in the same way as the mechanical vibration at the time of valve opening and is detected by the cylinder pressure sensor 140 as a change in the cylinder pressure. As in Fig. As shown in Figure 9, there is therefore a fluctuation in the amplitude of the output signal S2 of the cylinder pressure sensor 140 after time t2.

[0098] The output signal S2 of the cylinder pressure sensor 140 also exhibits a voltage shift corresponding to the presence or absence of the valve closing force before and after the amplitude fluctuation at the time of valve opening and closing. This voltage shift indicates a pressure difference ΔP between the pressure in cylinder 150 when the fuel injector 134 is in a closed state (i.e., the cylinder pressure detected by the cylinder pressure sensor 140 before the nozzle needle 1346, which is the valve body, is separated from the seat area of ​​the nozzle body 1345, which is the valve seat) and the pressure in cylinder 150 when the fuel injector 134 is in an open state (i.e., the cylinder pressure detected by the cylinder pressure sensor 140 when the nozzle needle 1346 is separated from the seat area of ​​the nozzle body 1345).

[0099] The valve closing force of the fuel injector 134 is determined by the sum of the force with which the spring 1351 presses the nozzle needle 1346 against the seat area of ​​the nozzle body 1345 and the fuel pressure supplied to the fuel injector 134 by the pressure pump 132. When the fuel injector 134 is in the closed state, the cylinder pressure sensor 140 detects the pressure in the cylinder 150 plus the valve closing force as the cylinder pressure. However, when the fuel injector 134 is in the open state, the valve closing force is released, and thus the cylinder pressure sensor 140 detects only the pressure in the cylinder 150. This generates a pressure difference ΔP in the measurement result of the cylinder pressure sensor 140, corresponding to the opening and closing of the fuel injector 134.

[0100] In this embodiment, the fuel pressure control unit 90 detects the pressure difference ΔP from the output signal S2 of the cylinder pressure sensor 140 and controls the operation of the pressurization pump 132, adjusting the fuel pressure so that the pressure difference ΔP approaches a predetermined setpoint. Consequently, the pressure of the fuel supplied by the pressurization pump 132 to the fuel injector 134 is regulated to reduce it as much as possible within the range of the valve closing force in which oil tightness can be ensured. As a result, a reduction in the drive power of the fuel injector 134 is possible.

[0101] The valve closing force can be calculated from the pressure difference ΔP, and the fuel pressure can be regulated by controlling the operation of the pressurization pump 132 so that the valve closing force approaches a predetermined setpoint. For example, the valve closing force can be calculated from the pressure difference ΔP using a formula determined beforehand, either computationally or empirically.

[0102] Fig. Figure 10 is a flowchart illustrating a method for controlling fuel pressure according to the embodiment. The flowchart of Fig. 10 is executed by the control device 1 in predetermined processing cycles when the internal combustion engine 100 is switched on. Step S101

[0103] In step S101, the fuel pressure control unit 90 determines whether the internal combustion engine 100 is in a predetermined low fuel pressure requirement state. The low fuel pressure requirement state is a state in which the load on the internal combustion engine 100 is low and the required pressure for the fuel injected by the fuel injector 134 is low. Under normal operating conditions of the internal combustion engine 100, it is not necessary for the fuel injector 134 to inject fuel at high pressure in a continuous operating state, except at startup or during periods of high power output. Therefore, in this embodiment, when the internal combustion engine 100 is in a continuous operating state, it is determined that the engine 100 is in a low fuel pressure requirement state, and the fuel pressure is regulated according to the valve closing force.

[0104] Fig. Figure 11 is a schematic representation illustrating the state of low fuel pressure requirement. If, as in Fig. As shown in Figure 11, if the rotational speed Ne of the internal combustion engine 100 is equal to or greater than a predetermined value and the torque is less than a predetermined value, the internal combustion engine 100 is in a state of low fuel pressure demand and it is determined that the fuel pressure control is applied. That is, in step S101 of Fig. Step 10 can be used to determine, based on the rotational speed and output torque of the internal combustion engine 100, whether the engine 100 is in a low fuel pressure demand state. If it is determined that the engine 100 is in a low fuel pressure demand state, the process proceeds to step S103; if it is determined that the engine 100 is not in a low fuel pressure demand state, the process continues with step S102. Step S102

[0105] In step S102, the fuel pressure control unit 90 controls the operation of the pressurization pump 132 so that the fuel pressure remains constant. In this case, for example, the fuel pressure control unit 90 sets a target value for the fuel pressure to a predetermined maximum pressure and outputs the fuel pressure control information S11 to the pressurization pump 132 according to the target value. After step S102 is executed, the process returns to step S101, waits until the next processing cycle, and then continues processing from step S101. Step S103

[0106] In step S103, the fuel pressure control unit 90 sets a target value Pt with respect to the pressure difference ΔP. Here, for example, the target value Pt is set according to the operating state of the internal combustion engine 100 based on the map information previously stored in the control device 1. The map information used at this time can be determined from previous calculations and experimental results. At this point, the target value Pt can also be changed to reflect long-term changes in the fuel injector 134 or the cylinder pressure sensor 140. For example, the fuel injection history of the fuel injector 134 is stored, and when the number of injections (the number of valve closures) reaches a predetermined number, the target value Pt is changed to a higher value than before.Even if the oil tightness of the fuel injector 134 or the sensitivity of the cylinder pressure sensor 140 decreases due to long-term changes, the pressure of the fuel supplied by the pressure pump 132 to the fuel injector 134 can be appropriately regulated in this way. Step S104

[0107] In step S104, the fuel pressure control unit 90 detects the pressure difference ΔP from the output signal S2 of the cylinder pressure sensor 140. The output signal S2 of the cylinder pressure sensor 140 is detected at the time the excitation pulse of the valve opening control signal S9 output by the fuel injection control unit 82 is switched on, or at the time before, and the output signal S2 of the cylinder pressure sensor 140 is detected at the time the excitation pulse of the valve opening control signal S9 is switched off, after a certain period of time has elapsed since that time. The pressure difference ΔP is then determined by calculating a difference in the detected output signal S2. Step S105

[0108] In step S105, the fuel pressure control unit 90 compares the setpoint Pt set in step S103 with the pressure difference ΔP detected in step S104. If Pt ≈ ΔP, that is, if the difference between the setpoint Pt and the detected pressure difference ΔP is less than a predetermined value, the process returns to step S101, waits until the next processing cycle, and then continues processing from step S101. However, if, as a result of the comparison of the setpoint Pt and the pressure difference ΔP in step S105, Pt < ΔP, that is, if the detected pressure difference ΔP is greater than the setpoint Pt, the process continues with step S106. If Pt > ΔP, that is, if the detected pressure difference ΔP is less than the setpoint Pt, the process continues with step S108. Steps S106 and S107

[0109] In step S106, the fuel pressure control unit 90 controls the operation of the pressurization pump 132 so that the fuel pressure decreases. Accordingly, the operation of the pressurization pump 132 is controlled to adjust the fuel pressure so that the pressure differential ΔP approaches the setpoint Pt. In the subsequent step S107, the fuel injection control unit 82 broadens the excitation pulse of the valve opening control signal S9 to actuate the fuel injector 134 in such a way that a fuel injection period, i.e., a period from opening to closing of the fuel injection orifice formed in the nozzle body 1345 of the fuel injector 134, is extended. This reduces the valve closing force without changing the fuel injection quantity. After execution of step S107, the process returns to step S101, waits until the next processing cycle, and then continues processing from step S101. Steps S108 and S109

[0110] In step S108, the fuel pressure control unit 90 controls the operation of the pressurization pump 132 to increase the fuel pressure. Accordingly, the operation of the pressurization pump 132 is controlled to adjust the fuel pressure so that the pressure differential ΔP approaches the setpoint Pt. In the subsequent step S109, the fuel injection control unit 82 narrows the excitation pulse of the valve opening control signal S9 to actuate the fuel injector 134 in such a way that the fuel injection period, i.e., the period from opening to closing of the fuel injection orifice formed in the nozzle body 1345 of the fuel injector 134, is shortened. Accordingly, the valve closing force is increased without changing the fuel injection quantity. After execution of step S109, the process returns to step S101, waits until the next processing cycle, and then continues processing from step S101.

[0111] According to the embodiment described above, the following operational effects can be observed. (1) The control device 1 for an internal combustion engine comprises the fuel pressure control unit 90, which regulates the pressure of the fuel supplied to the fuel injector 134, which injects the fuel into the internal combustion engine 100. The fuel injector 134 comprises the nozzle needle 1346, which is the valve body, the solenoid coil 1353, which is the actuating unit for actuating the nozzle needle 1346, and the nozzle body 1345, in which the fuel injection orifice is formed, which opens and closes according to the actuating of the nozzle needle 1346. The cylinder pressure sensor 140, which detects the cylinder pressure, which is a pressure in the combustion chamber of the internal combustion engine 100, is attached to the internal combustion engine 100.The fuel pressure control unit 90 regulates the fuel pressure based on the pressure difference ΔP between the cylinder pressure sensor 140 detecting the cylinder pressure before the nozzle needle 1346 is separated from the seat area of ​​the nozzle body 1345, which is the valve seat, and the cylinder pressure sensor 140 detecting the cylinder pressure sensor when the nozzle needle 1346 is separated from the seat area of ​​the nozzle body 1345. This allows the fuel pressure to be appropriately regulated according to the valve closing force of the fuel injector 134. (2) The fuel pressure control unit 90 regulates the fuel pressure so that the pressure difference ΔP approaches the predetermined setpoint Pt (steps S105 to S109). This allows the fuel pressure to be reliably regulated according to the valve closing force of the fuel injector 134. (3) The fuel pressure control unit 90 can change the setpoint Pt according to the fuel injection history of the fuel injector 134 (step S103). Accordingly, the fuel pressure can be appropriately regulated taking into account the long-term changes of the fuel injector 134 or the cylinder pressure sensor 140. (4) The pressurization pump 132, which pressurizes the fuel, is attached to the internal combustion engine 100. The fuel pressure control unit 90 controls the operation of the pressurization pump 132 to regulate the fuel pressure. Accordingly, the fuel pressure can be reliably controlled. (5) The control device 1 for an internal combustion engine also includes the fuel injection control unit 82, which controls the fuel injection valve 134. The fuel injection control unit 82 changes the opening / closing period of the fuel injection orifice according to the control result of the fuel pressure by the fuel pressure control unit 90 (steps S107 and S109). Accordingly, the fuel pressure can be regulated without changing the amount of fuel injected. (6) The fuel pressure control unit 90 determines, based on the speed and output torque of the internal combustion engine 100, whether the internal combustion engine 100 is in a low fuel pressure demand state (step S101), and, if the determination shows that the internal combustion engine 100 is not in a low fuel demand state (step S101: No), the fuel pressure control unit 90 does not regulate the fuel pressure based on the pressure differential ΔP (step S102). Accordingly, the fuel pressure can be regulated according to the valve closing force of the fuel injector 134 without affecting the operation of the internal combustion engine 100. (7) In the fuel injector 134, the fuel injection port is located in the combustion chamber of the internal combustion engine 100. The cylinder pressure sensor 140 comprises the diaphragm 1411, which is located closer to the combustion chamber than the fuel injection port and is the pressure receiving unit, and the pressure sensing element 1412, which is the pressure sensing unit that detects the pressure detected by the diaphragm 1411 as the cylinder pressure. Accordingly, the cylinder pressure sensor 140 can detect the valve closing force of the fuel injector 134 as a pressure differential ΔP. (8) The fuel pressure control unit 90 regulates the pressure of the fuel in the fuel line 133, which is arranged between the fuel tank 130 for storing the fuel and the fuel injector 134. Accordingly, the pressure of the fuel supplied to the fuel injector 134 can be appropriately regulated according to the valve closing force of the fuel injector 134.

[0112] In the embodiment described above, the example is presented in which the cylinder pressure sensor 140 is provided at the tip of the fuel injector 134. However, the arrangement of the cylinder pressure sensor 140 is not limited to this. The cylinder pressure sensor 140 can be arranged at any position, as long as the combustion pressure (cylinder pressure) of the internal combustion engine 100 can be measured appropriately and the pressure differential ΔP corresponding to the valve closing force of the fuel injector 134 can be reliably measured. Furthermore, the cylinder pressure sensor 140 and the fuel injector 134 do not have to be integrated together and can be arranged as separate components in the internal combustion engine 100.

[0113] In the embodiment described above, each in Fig.The functional design of the control device 1 described in section 2 can be implemented by software executed by the MPU 50, as described above, or by hardware such as a field-programmable gate array (FPGA). These can also be used in combination.

[0114] An example of an embodiment of the present invention is described above. However, the present invention can be a combination of all the embodiments described above, or a combination of two or more embodiments is preferred.

[0115] Furthermore, the present invention is not limited to including all embodiments of the above-described embodiments, and some embodiments of the above-described embodiments are replaced by embodiments of other embodiments. Alternatively, the embodiment of the above-described embodiment can be replaced by embodiments of other embodiments.

[0116] Furthermore, some features of the embodiments described above can be added, removed, or replaced by features of other embodiments.

[0117] The embodiment and various modifications described above are merely examples, and the invention is not limited to these, except to the extent that the characterizing features of the invention are affected. Although various embodiments and modifications are described above, the invention is not limited to these. Other embodiments considered to be related to the technical concept of the present invention are also included within its scope. List of reference symbols 1 Control device 5a Intake camshaft 5b Exhaust camshaft 6a Inlet valve 6b Exhaust valve 10 analog input units 20 digital input units 30 A / D converters 40 RAM 50 MPU 60 ROM 70 I / O ports 80, 80a Output circuit 81 Total control unit 82 Fuel injection control unit 83 Ignition control unit 84 cylinder determination unit 85 Angle Information Generation Unit 86 Speed ​​information generation unit 87 Intake quantity measuring unit 88 Load Information Generation Unit 89 Water temperature measuring unit 90 Fuel pressure control unit 91 Fuel pressure measuring unit 100 internal combustion engine 110 air filters 111 Intake manifold 112 Intake manifold 113 Throttle valve 113a Throttle opening sensor 114 Flow rate sensor 115 Intake air temperature sensor 116 Intake pressure sensor 120 toothed ring 121 Crank angle sensor 122 Water temperature sensor 123 Crankshaft 125 Accelerator pedal 126 Accelerator pedal position sensor 130 fuel tank 131 Pump 132 Pressure pump 133 Fuel line 134 Fuel injector 135 Fuel pressure sensor 140 cylinder pressure sensor 150 cylinders 160 Exhaust manifold 161 Three-way catalyst 162 Upstream air-fuel ratio sensor 163 Downstream air-fuel ratio sensor 164 Exhaust gas temperature sensor 170 pistons 180 cylinder head 200 spark plug 300 Ignition coil 500 pump control cams 1321 Suction valve 1322 Pressurization chamber 1323 plunger pistons 1324 pestles 1325 Compression spring 1326 Discharge valve 1331 common rail 1341 Tolerance ring 1342 Nozzle holders 1343 core 1344 Housing 1345 Nozzle body 1346 Jet needle 1347 anchors 1348 Upstream needle guide 1349 downstream needle guide 1350 ring seal 1351 spring 1352 regulating bolts 1353 Magnetic coil 1354 O-ring 1355 Support ring 1356 filters 1357 wire 1411 Membran 1412 Pressure detection element 1413 wire 1414 Charge Amplifiers 1415 connection

Claims

[1] Control device (1) for an internal combustion engine (100), comprising: a fuel pressure control unit (90) configured to regulate the pressure of a fuel supplied to a fuel injector (134) configured to inject the fuel into an internal combustion engine (100), wherein the fuel injector (134) comprises a valve body, an actuating unit for actuating the valve body, and a fuel injection orifice which is opened or closed according to the actuating of the valve body, wherein a cylinder pressure sensor (140), configured to detect an internal cylinder pressure, which is a pressure in a combustion chamber of the internal combustion engine (100), is attached to the internal combustion engine (100), and wherein the fuel pressure control unit (90) is configured to control the fuel pressure based on a pressure difference between the cylinder internal pressure detected by the cylinder pressure sensor (140) before the valve body is separated from a valve seat and the cylinder internal pressure detected by the cylinder pressure sensor (140) when the valve body is separated from the valve seat. [2] Control device (1) for an internal combustion engine (100) according to claim 1, wherein the fuel pressure control unit (90) is configured to regulate the pressure of the fuel so that the pressure difference approaches a predetermined setpoint. [3] Control device (1) for an internal combustion engine (100) according to claim 2, wherein the fuel pressure control unit (90) is configured to change the setpoint according to an injection history of the fuel through the fuel injection valve (134). [4] Control device (1) for an internal combustion engine (100) according to one of claims 1 to 3, wherein a pressurizing pump (132) which is designed to pressurize the fuel, is attached to the internal combustion engine (100) and The fuel pressure control unit (90) is set up to control the operation of the pressure pump (132) to regulate the fuel pressure. [5] Control device (1) for an internal combustion engine (100) according to one of claims 1 to 3, further comprising: a fuel injection control unit (82), configured to control the fuel injection valve (134), wherein the fuel injection control unit (82) is configured to change an opening / closing period of the fuel injection orifice according to a control result of the fuel pressure by the fuel pressure control unit (90). [6] Control device (1) for an internal combustion engine (100) according to one of claims 1 to 3, wherein the fuel pressure control unit (90) is configured to determine, based on the speed and output torque of the internal combustion engine (100), whether the internal combustion engine (100) is in a state of low fuel pressure requirement or not, and the fuel pressure control unit (90) is further configured to not regulate the fuel pressure based on the pressure difference if the determination shows that the internal combustion engine (100) is not in a state of low fuel requirement. [7] Control device (1) for an internal combustion engine (100) according to one of claims 1 to 3, wherein in the fuel injection valve (134) the fuel injection hole is arranged in a combustion chamber of the internal combustion engine (100) and The cylinder pressure sensor (140) comprises a pressure receiving unit located closer to the combustion chamber than the fuel injection hole and a pressure sensing unit configured to detect pressure received by the pressure receiving unit as cylinder internal pressure. [8] Control device (1) for an internal combustion engine (100) according to one of claims 1 to 3, wherein the fuel pressure control unit (90) is configured to control the pressure of the fuel in a fuel line (133) which is arranged between a fuel tank (130) for storing the fuel and the fuel injection valve (134).

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