Supercharging system

Abstract

To reduce boost pressure of intake air to maintain an intake amount of the intake air at a predetermined amount.SOLUTION: A supercharging system S includes: an intake valve 20 that regulates suction of intake air to an engine 10; a variable mechanism 60 that regulates opening / closing timing of the intake valve 20; a supercharger 50 that compresses the intake air by using a flow of exhaust gas from an engine 10; a loss acquisition section 124 that acquires loss information indicating a degree of an increase of pump loss of the engine 10; and a supercharging control section 126 that controls boost pressure of the intake air by the supercharger 50 to maintain an intake amount of the intake air at a predetermined amount when the degree of the increase of the pump loss is larger than a predetermined degree.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a supercharging system. [Background technology]

[0002] Among supercharging systems that supercharge the intake air of an internal combustion engine, there are those that have a turbocharger that adjusts the intake supercharging pressure by controlling the opening degree of the turbine's variable nozzle, and a variable valve mechanism that can control the opening and closing timing of the intake valve (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-2100 A Summary of the Invention [Problem to be solved by the invention]

[0004] Since the turbocharger operates to maintain a constant boost pressure when supercharging the intake air, the amount of intake air into the engine increases as a result of supercharging, depending on the operating conditions of the engine. If the amount of intake air increases, the work done by the engine in the exhaust stroke increases, which may result in a deterioration in fuel efficiency.

[0005] The present invention has been made in consideration of these points, and has an object to suppress deterioration of fuel efficiency when controlling a turbocharger. [Means for solving the problem]

[0006] One aspect of the present invention provides a supercharging system comprising: an intake valve that adjusts the intake of intake air into an internal combustion engine; a variable mechanism that adjusts opening and closing timing of the intake valve; a supercharger that compresses the intake air by utilizing an exhaust flow from the internal combustion engine; an acquisition unit that acquires loss information indicating a degree of increase in pumping loss of the internal combustion engine; and a control unit that controls a supercharging pressure of the intake air by the supercharger so as to maintain an intake amount of the intake air at a predetermined amount when the degree of increase in the pumping loss is greater than a predetermined degree.

[0007] The control unit may also reduce a supercharging pressure of the intake air so as to maintain an intake amount of the intake air at a predetermined amount.

[0008] The control unit may also control a supercharging pressure of the intake air by the supercharger at a timing when the intake valve is closed so as to maintain an intake amount of the intake air at a predetermined amount.

[0009] The acquisition unit may further include a determination unit that acquires an exhaust pressure of the exhaust gas and an intake pressure of the intake gas as the loss information, and determines that a degree of increase in the pumping loss is greater than a predetermined degree when a difference between the exhaust pressure and the intake pressure is greater than a predetermined value.

[0010] In addition, the control unit may be configured to reduce the intake boost pressure so as to maintain the intake amount of the intake air at a predetermined amount when a degree of increase in the pumping loss is greater than a predetermined degree when the variable mechanism adjusts the opening / closing timing.

[0011] Furthermore, the control unit may be configured to control an opening degree of a nozzle of a turbine of the turbocharger so that a supercharging pressure of the intake air by the turbocharger becomes a predetermined value when a degree of increase in the pumping loss is equal to or less than a predetermined degree when the variable mechanism adjusts the opening / closing timing.

[0012] Furthermore, the control unit may cause the variable mechanism to adjust the opening / closing timing when a rotation speed of the internal combustion engine is lower than a predetermined speed and a torque of the internal combustion engine is lower than a predetermined value. Effect of the Invention

[0013] According to the present invention, it is possible to suppress deterioration of fuel efficiency when controlling a turbocharger. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a supercharging system S according to one embodiment. [Diagram 2] FIG. 2 is a block diagram showing a detailed configuration of a control device 100. [Diagram 3] 2 is a schematic diagram showing operating conditions of the engine 10 in which the opening and closing timing is adjusted by the variable mechanism 60. FIG. [Figure 4] 5 is a time chart showing the relationship between the intake amount and the supercharging pressure in the second supercharging control. [Diagram 5] 4 is a flowchart showing an example of the operation of the control device 100. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] <Supercharging system configuration> Fig. 1 is a schematic diagram showing the configuration of a supercharging system S according to one embodiment. The supercharging system S is a system that supercharges the intake air introduced into an engine 10, and is mounted on a vehicle in this embodiment. As shown in Fig. 1, the supercharging system S has an engine 10, an intake valve 20, an exhaust valve 25, an intake passage 30, an exhaust passage 40, a supercharger 50, a variable mechanism 60, a supercharging pressure sensor 70, an intake pressure sensor 72, an exhaust pressure sensor 73, and a control device 100.

[0016] The engine 10 is an internal combustion engine that generates power by combusting and expanding a mixture of intake air and fuel in a combustion chamber 11. In this embodiment, the engine 10 is a diesel engine. The engine 10 has a cylinder block 12 and a cylinder head 13.

[0017] A cylinder 15 is formed within the cylinder block 12 and houses a piston 14 that is capable of reciprocating motion. The cylinder head 13 is provided with an intake port 16 that introduces intake air into the combustion chamber 11, and an exhaust port 17 that discharges exhaust gas from the combustion chamber 11. The cylinder head 13 also is provided with an injector 18 that injects fuel into the combustion chamber 11.

[0018] The intake valve 20 is provided in the cylinder head 13 and opens and closes the intake port 16. The intake valve 20 opens and closes to adjust the inflow of intake air to the engine 10. The exhaust valve 25 is provided in the cylinder head 13 and opens and closes the exhaust port 17. The exhaust valve 25 opens and closes to adjust the outflow of exhaust air from the engine 10.

[0019] The intake passage 30 is a flow path that introduces intake air (air) into the engine 10. When the intake valve 20 is open, the intake air flows from the intake passage 30 into the combustion chamber 11. An air cleaner 32, a compressor 54 of the turbocharger 50, and an intercooler 34 are provided in the intake passage 30. The intercooler 34 cools the intake air compressed by the compressor 54.

[0020] The exhaust passage 40 is a passage that guides exhaust gas from the engine 10 to the atmosphere. When the exhaust valve 25 is open, exhaust gas flows out from the combustion chamber 11 to the exhaust passage 40. A turbine 52 of a turbocharger 50 and an exhaust purification device 42 are provided in the exhaust passage 40.

[0021] The supercharger 50 is a turbocharger that compresses the intake air by utilizing the flow of exhaust gas. The supercharger 50 has a turbine 52 and a compressor 54. The turbine 52 is driven by the exhaust gas flowing through the exhaust passage 40. The compressor 54 is connected to the turbine 52 via a connecting shaft, and compresses the intake air in conjunction with the rotation of the turbine 52. The turbine 52 has a nozzle therein, and the supercharging pressure of the intake air can be adjusted by controlling the nozzle opening.

[0022] The variable mechanism 60 is a mechanism that adjusts the opening and closing timings of the intake valve 20 and the exhaust valve 25. The variable mechanism 60 is, for example, an electromagnetically driven mechanism that directly opens and closes the intake valve 20 and the like by the electromagnetic force of an electromagnetic solenoid, but is not limited to this and may be a cam switching mechanism that can switch between multiple cams with different cam profiles. The variable mechanism 60 advances the opening and closing timings of the intake valve 20 and the exhaust valve 25 from a reference timing (also called advance), or delays the opening and closing timings of the intake valve 20 and the exhaust valve 25 from a reference timing (also called retard). Note that when the intake valve 20 and the exhaust valve 25 open and close at the reference timing, the variable mechanism 60 does not operate.

[0023] The supercharging pressure sensor 70 detects the supercharging pressure of the intake air by the supercharger 50. The supercharging pressure sensor 70 is located downstream of the compressor 54 of the supercharger 50 in the intake passage 30. The intake pressure sensor 72 detects the pressure of the intake air flowing into the engine 10. The intake pressure sensor 72 is located upstream of the engine 10 in the intake passage 30. The exhaust pressure sensor 73 detects the pressure of the exhaust gas flowing out from the engine 10. The exhaust pressure sensor 74 is located downstream of the engine 10 in the exhaust passage 40.

[0024] The control device 100 controls the operation of the supercharging system S. For example, the control device 100 controls the opening and closing of the intake valve 20 and the exhaust valve 25 by the variable mechanism 60, and controls the supercharging of the intake air based on the supercharging pressure detected by the supercharging pressure sensor 70. The control device 100 switches between two supercharging controls (first supercharging control and second supercharging control) based on the operating state of the engine 10 in order to suppress deterioration of fuel efficiency when controlling the supercharger 50, as will be described in detail later.

[0025] <Detailed configuration of the control device> 2 is a block diagram showing a detailed configuration of the control device 100. The control device 100 includes a storage unit 110 and a control unit 120.

[0026] The storage unit 110 includes, for example, a read only memory (ROM) and a random access memory (RAM). The storage unit 110 stores programs and various data to be executed by the control unit 120.

[0027] The control unit 120 is a processor such as a CPU (Central Processing Unit), etc. The control unit 120 executes a program stored in the storage unit 110 to function as a state acquisition unit 122, a valve control unit 123, a loss acquisition unit 124, a determination unit 125, and a supercharging control unit 126.

[0028] The state acquisition unit 122 acquires the operating state of the engine 10. For example, the state acquisition unit 122 acquires the rotation speed and torque of the engine 10 from the engine detection unit 80. The engine detection unit 80 includes a speed sensor that detects the rotation speed of the engine 10 and a torque sensor that detects the torque of the engine 10.

[0029] The valve control unit 123 controls the opening and closing of the intake valve 20 and the exhaust valve 25 when the engine 10 is operating. The valve control unit 123 normally opens and closes the intake valve 20 and the exhaust valve 25 at a predetermined timing (reference timing). The valve control unit 123 also operates the variable mechanism 60 to adjust the opening and closing timing of the intake valve 20 and the exhaust valve 25 from the reference timing. For example, the valve control unit 123 operates the variable mechanism 60 to make the opening and closing timing of the intake valve 20 earlier than the reference timing (advance angle) or to make the opening and closing timing of the intake valve 20 later than the reference timing (retard angle).

[0030] When the operating state of the engine 10 acquired by the state acquisition unit 122 satisfies a predetermined condition, the valve control unit 123 operates the variable mechanism 60 to adjust the opening and closing timings of the intake valve 20 and the exhaust valve 25. When the operating state of the engine 10 does not satisfy the predetermined condition, the valve control unit 123 opens and closes the intake valve 20 and the exhaust valve 25 at a reference timing.

[0031] Fig. 3 is a schematic diagram showing the operating conditions of engine 10 whose opening and closing timings are adjusted by variable mechanism 60. In Fig. 3, the horizontal axis represents the rotation speed of engine 10, and the vertical axis represents engine torque. Region R at the bottom left (region where rotation speed is low and engine torque is low) represents the operating conditions of engine 10 whose opening and closing timings of intake valve 20 and exhaust valve 25 are adjusted by variable mechanism 60. That is, when the rotation speed of engine 10 is lower than a predetermined speed and the torque of engine 10 is lower than a predetermined value, valve control unit 123 operates variable mechanism 60 to adjust the opening and closing timing of intake valve 20.

[0032] The loss acquiring unit 124 acquires loss information indicating the degree of increase in the pumping loss of the engine 10. For example, the loss acquiring unit 124 acquires the loss information when the valve control unit 123 operates the variable mechanism 60 to advance or retard the intake valve 20. The pumping loss of the engine 10 is an energy loss that occurs in the intake stroke and the exhaust stroke of the engine 10.

[0033] Loss acquiring unit 124 acquires the exhaust pressure of the exhaust and the intake pressure of the intake as loss information. Specifically, loss acquiring unit 124 acquires the pressure difference between the exhaust pressure and the intake pressure as loss information. When pumping loss occurs, the exhaust pressure is higher than the intake pressure. When the pressure difference obtained by subtracting the intake pressure from the exhaust pressure is large, the increase in pumping loss is large (i.e., the pumping loss is worsening), but when the pressure difference is small, the increase in pumping loss is small. Loss acquiring unit 124 acquires the intake pressure from intake pressure sensor 72 and the exhaust pressure from exhaust pressure sensor 74.

[0034] The determination unit 125 determines the degree of the pumping loss of the engine 10. The determination unit 125 determines whether the degree of increase in the pumping loss of the engine 10 is greater than a predetermined degree, based on the loss information acquired by the loss acquisition unit 124. The determination unit 125 outputs the determination result to the supercharging control unit 126.

[0035] When the pressure difference between the exhaust pressure and the intake pressure acquired by the loss acquisition unit 124 is greater than a predetermined value, the determination unit 125 determines that the degree of increase in the pumping loss is greater than a predetermined degree. That is, the determination unit 125 determines that the deterioration of the pumping loss is large. On the other hand, when the pressure difference is equal to or less than the predetermined value, the determination unit 125 determines that the degree of increase in the pumping loss is equal to or less than the predetermined degree. That is, the determination unit 125 determines that the deterioration of the pumping loss is small.

[0036] The supercharging control unit 126 controls the supercharging of the intake air by the supercharger 50. For example, the supercharging control unit 126 controls the supercharging of the intake air by the supercharger 50 based on the supercharging pressure detected by the supercharging pressure sensor 70. Specifically, the supercharging control unit 126 controls the nozzle opening degree of the turbine 52 of the supercharger 50 so that the supercharging pressure is maintained at a predetermined value.

[0037] The supercharging control unit 126 performs first supercharging control or second supercharging control based on the operating state of the engine 10, etc. The first supercharging control is a control that adjusts the nozzle opening of the turbine 52 so that the intake supercharging pressure becomes constant. The second supercharging control is a control that adjusts the supercharging pressure so that the intake amount of intake air becomes constant. Note that when the first supercharging control is performed, the intake amount of intake air increases.

[0038] The supercharging control unit 126 performs the first supercharging control when the operating state of the engine 10 falls within a region other than region R in Fig. 3 (a region in which the rotation speed is higher than a predetermined speed and the engine torque is higher than a predetermined value). Moreover, the supercharging control unit 126 performs the first supercharging control in a situation in which the pumping loss of the engine 10 does not worsen. When performing the first supercharging control, the supercharging control unit 126 adjusts the nozzle opening of the turbine 52 so that the supercharging pressure detected by the supercharging pressure sensor 70 becomes constant.

[0039] The supercharging control section 126 performs the second supercharging control if the pressure difference between the exhaust pressure and the intake pressure is greater than a predetermined value when the variable mechanism 60 operates. That is, if the degree of increase in pumping loss is greater than a predetermined degree when the variable mechanism 60 adjusts the opening / closing timing, the supercharging control section 126 controls the supercharging pressure of the intake air by the supercharger 50 so as to maintain the intake amount of the intake air at a predetermined amount.

[0040] FIG. 4 is a time chart showing the relationship between the intake amount and the boost pressure in the second supercharging control. In FIG. 4, the solid line shows the intake amount and the boost pressure in the second supercharging control, and the dashed line shows the intake amount and the boost pressure in the comparative example. Time t1 shown in FIG. 4 is the closing timing (the timing at which the intake valve 20 starts to close) whose opening and closing timing has been adjusted by the variable mechanism 60. At time t1, the intake valve 20 starts to close, and the supercharging control unit 126 also starts the second supercharging. The supercharging control unit 126 reduces the supercharging pressure after time t1. At this time, the supercharging control unit 126 increases the nozzle opening of the turbine 52 to reduce the supercharging pressure.

[0041] The supercharging control unit 126 performs the second supercharging control so that the amount of intake air does not increase after the intake valve 20 is closed. Specifically, as shown in FIG. 4, the supercharging control unit 126 reduces the intake supercharging pressure so as to maintain the amount of intake air at a predetermined amount. Since the amount of intake air taken into the engine 10 does not increase while the second supercharging control is being performed, the pump loss also decreases after time t1 as shown in FIG. 4. This also improves fuel efficiency after time t1. That is, fuel efficiency improves when the supercharging control unit 126 is performing the second supercharging control.

[0042] The supercharging control unit 126 controls the supercharging pressure of the intake air by the supercharger 50 so as to maintain the intake amount of the intake air at a predetermined amount at the timing when the intake valve 20 closes. Specifically, as shown in Fig. 4, when the intake valve 20 starts to close, the supercharging control unit 126 reduces the supercharging pressure of the intake air so as to maintain the intake amount constant. The supercharging control unit 126 gradually reduces the supercharging pressure and then keeps the supercharging pressure constant. The supercharging control unit 126 adjusts the nozzle opening of the turbine 52 so as to change the supercharging pressure in this manner.

[0043] When the variable mechanism 60 is operating and the pressure difference between the exhaust pressure and the intake pressure is larger than a predetermined value, if the supercharging control unit 126 performs supercharging control to keep the supercharging pressure constant, unlike the present embodiment, the amount of intake air increases after time t1, as shown by the dashed line in FIG. 4, and the pumping loss worsens.

[0044] The supercharging control unit 126 performs the first supercharging control instead of the second supercharging control if the degree of increase in pumping loss is equal to or less than a predetermined degree (pressure difference between exhaust pressure and intake pressure) when the variable mechanism 60 adjusts the opening / closing timing. That is, while the variable mechanism 60 adjusts the opening / closing timing, if the degree of increase in pumping loss is equal to or less than a predetermined degree, the supercharging control unit 126 controls the nozzle opening degree of the turbine 52 of the supercharger 50 so that the supercharging pressure of the intake air by the supercharger 50 becomes a predetermined value. As a result, in cases where the pumping loss does not worsen, the intake air can be supercharged while allowing an increase in the intake amount, thereby achieving high output of the engine 10.

[0045] <Example of control device operation> Fig. 5 is a flowchart showing an example of the operation of the control device 100. The process shown in Fig. 5 is executed continuously while the engine 10 is operating.

[0046] 5 starts with the state acquisition unit 122 acquiring the operating state of the engine 10 (step S102). For example, the state acquisition unit 122 acquires the rotation speed and engine torque of the engine 10.

[0047] Next, the valve control unit 123 determines whether or not the operating state of the engine 10 satisfies the operating condition for operating the variable mechanism 60 (step S104). When the operating state of the engine 10 is included in the region R shown in FIG. 3, the valve control unit 123 determines that the operating condition is satisfied.

[0048] If the operating conditions are met in step S104 (Yes), the valve control unit 123 operates the variable mechanism 60 (step S106) to adjust the opening and closing timings of the intake valve 20 and the exhaust valve 25. For example, the variable mechanism 60 advances the opening and closing timing of the intake valve 20 relative to a reference timing (advance).

[0049] Next, the loss obtaining unit 124 obtains the intake pressure and the exhaust pressure to grasp the degree of the pumping loss (step S108). The loss obtaining unit 124 obtains the intake pressure detected by the intake pressure sensor 72 and the exhaust pressure detected by the exhaust pressure sensor 74.

[0050] Next, the determination unit 125 determines whether or not the pressure difference between the intake pressure and the exhaust pressure acquired by the loss acquisition unit 124 is greater than a predetermined value (step S110). If the pressure difference is greater than the predetermined value, the engine 10 is in an operating state in which the pumping loss worsens.

[0051] If the pressure difference is greater than the predetermined value in step S110 (Yes), the supercharging control unit 126 performs the second supercharging control (step S112). Specifically, the supercharging control unit 126 reduces the supercharging pressure of the intake air so that the intake amount of the intake air is maintained at a predetermined amount.

[0052] On the other hand, if the pressure difference is equal to or less than the predetermined value in step S110 (No), the supercharging control unit 126 performs the first supercharging control (step S114). Specifically, the supercharging control unit 126 adjusts the nozzle opening of the turbine 52 so that the intake supercharging pressure becomes constant. Note that, even if the operating conditions are not satisfied in step S104 (No), the supercharging control unit 126 performs the first supercharging control (step S114).

[0053] <Effects of this embodiment> When the degree of increase in pumping loss is greater than a predetermined degree, the supercharging system S of this embodiment controls the supercharging pressure of the intake air by the supercharger 50 so as to maintain the intake amount of the intake air at a predetermined amount. Specifically, the supercharging control system S reduces the supercharging pressure of the intake air so as to maintain the intake amount at a predetermined amount. As a result, when the variable mechanism 60 is operating, the amount of intake air into the engine 10 does not increase when the intake air is supercharged, so that pumping loss can be reduced (see FIG. 3). As a result, the fuel efficiency of the engine 10 can also be improved.

[0054] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment resulting from the combination combines the effect of the original embodiment. [Explanation of symbols]

[0055] 10 Engine 20 Intake valve 50 Turbocharger 60 Variable Mechanism 123 Valve control section 124 Loss Acquisition Department 125 Judgment section 126 Supercharging control unit S Supercharging System

Claims

1. an intake valve for adjusting the intake of intake air into the internal combustion engine; a variable mechanism for adjusting the opening and closing timing of the intake valve; a supercharger that compresses the intake air by utilizing an exhaust flow from the internal combustion engine; an acquisition unit that acquires loss information indicating a degree of increase in a pump loss of the internal combustion engine; a control unit that controls a supercharging pressure of the intake air by the supercharger so as to maintain an intake amount of the intake air at a predetermined amount when a degree of increase in the pumping loss is greater than a predetermined degree; A supercharging system.

2. The control unit reduces a supercharging pressure of the intake air so as to maintain an intake amount of the intake air at a predetermined amount. The supercharging system according to claim 1 .

3. The control unit controls a supercharging pressure of the intake air by the supercharger so as to maintain an intake amount of the intake air at a predetermined amount at a timing when the intake valve is closed. The supercharging system according to claim 2 .

4. The acquisition unit acquires an exhaust pressure of the exhaust gas and an intake pressure of the intake gas as the loss information, a determination unit that determines that a degree of increase in the pumping loss is greater than a predetermined degree when a difference between the exhaust pressure and the intake pressure is greater than a predetermined value. The supercharging system according to claim 1 .

5. the control unit reduces a supercharging pressure of the intake air so as to maintain an intake amount of the intake air at a predetermined amount when a degree of increase in the pumping loss is greater than a predetermined degree when the variable mechanism adjusts the opening / closing timing. The supercharging system according to claim 1 .

6. the control unit controls an opening degree of a nozzle of a turbine of the turbocharger so that a supercharging pressure of the intake air by the turbocharger becomes a predetermined value when a degree of increase in the pumping loss is equal to or less than a predetermined degree when the variable mechanism adjusts the opening / closing timing. The supercharging system according to claim 5.

7. the control unit causes the variable mechanism to adjust the opening / closing timing when a rotation speed of the internal combustion engine is lower than a predetermined speed and a torque of the internal combustion engine is lower than a predetermined value. The supercharging system according to claim 1 .

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