JP2014047691A - Engine system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, in a vehicle packaging high-octane fuel and low-octane fuel therein, the high-octane fuel is used for canceling knocking but since it is necessary to invest the high-octane fuel equal to or more than required for actual knocking cancellation, efficiency is not high in some cases.SOLUTION: An engine system comprises a high-octane fuel tank, a low-octane fuel tank, a high-octane fuel injector communicated with the high-octane fuel tank, a low-octane fuel injector communicated with the low-octane fuel tank, a knocking sensor, and a control device connected with the knocking sensor, the high-octane fuel injector and the low-octane fuel injector. When knocking is detected, the control device performs control to retard ignition timing by increasing a ratio of fuel injection from the high-octane fuel injector.

Description

  The present invention relates to an engine control device for an automobile, and more particularly to an engine device using two types of fuel, a high-octane fuel and a low-octane fuel.

  In so-called reciprocating engines that rotate the crankshaft by reciprocating the piston in the cylinder, when the gas mixture of fuel and air is compressed by the piston, when to ignite and explode is important to increase thermal efficiency It becomes an element. Considering the case of a four-cycle engine, it is considered better to ignite when the piston reaches top dead center. However, since the combustion of the mixed gas is not performed instantaneously, it is actually recommended to ignite slightly before the top dead center (advance side). In order to increase the thermal efficiency, it is also effective to increase the compression ratio.

  In addition, there is a difference in the ease of self-ignition indicated by the octane number in the type of fuel used in the engine. For example, if a low octane fuel that is easy to ignite is used in an engine having a high compression ratio, knocking that starts self-ignition from another place in the combustion chamber occurs during the propagation of flame after ignition. When knocking occurs, the propagation pressures interfere with each other and generate an audible noise called “crisp”, and when this further proceeds, the temperature of the cylinder head, cylinder, piston, etc. becomes too high and may be damaged. Therefore, high-octane fuel that is difficult to self-ignite is used for engines with a relatively high compression ratio.

  However, high-octane fuel is easy to increase the thermal efficiency but expensive. That is, the apparent fuel consumption (travel distance per liter: hereinafter simply referred to as “fuel consumption”) is easy to increase, but the fuel cost is likely to deteriorate.

  Therefore, an internal combustion engine equipped with a high octane fuel and a low octane fuel and a control device for the same have been proposed as a method for avoiding knocking and improving thermal efficiency while preventing fuel costs from deteriorating. These proposals are intended to improve the combustion state only when necessary by supplying fuels having different octane numbers according to the operating state of the internal combustion engine, and to improve both fuel efficiency and fuel cost.

  Patent Document 1 discloses an internal combustion engine equipped with high-octane (high octane fuel) and regular (low-octane fuel). Here, for engines with a high compression ratio, regular fuel knocks at low speed and high load range, and high-octane fuel cannot exhibit high-octane characteristics at low and medium load ranges. An internal combustion engine that is mixed and supplied to an engine is disclosed.

  Also, in Patent Document 2, a high-octane fuel and a low-octane fuel are also mounted, and when knocking occurs, a large amount of high-octane fuel is supplied, and when knocking is eliminated, the amount of high-octane fuel is gradually reduced. An internal combustion engine and a control device for the same are disclosed. In Patent Document 2, when there is no high octane fuel, the ignition timing is retarded, and when knocking is still not resolved, knocking is eliminated by reducing the air amount.

Japanese Utility Model Publication No. 61-5341 JP 2009-293600 A

  When a high-octane fuel and a low-octane fuel are installed, there are two types of knocking elimination methods: retarding the ignition timing and supplying high-octane fuel. Patent Document 1 eliminates knocking by supplying a high octane fuel. Also, Patent Document 2 is basically the same, in which the ignition timing is retarded when the high-octane fuel disappears.

  As a characteristic of these two approaches to knocking, retarding the ignition timing can be dealt with instantaneously, but when dealing with high-octane fuel, excess high-octane fuel is introduced first. There is a need. In other words, when high-octane fuel is injected, more high-octane fuel must be injected than can actually eliminate knocking. That is, since expensive fuel is used excessively, it is expensive and fuel cost deteriorates.

  Further, if the ignition timing is retarded, the fuel efficiency is deteriorated because the thermal efficiency is lowered even though the fuel is consumed. Therefore, in patent documents 1 and 2, it cannot be said that the high octane fuel is effectively used.

  The present invention has been conceived in view of the above problems, and provides an engine device capable of obtaining a maximum output with a minimum amount of fuel. That is, the present invention provides an engine device that reduces the fuel cost per unit travel distance as much as possible.

More specifically, the engine device according to the present invention is:
A high-octane fuel tank,
A low octane fuel tank,
A high octane fuel injector in communication with the high octane fuel tank;
A low octane fuel injector in communication with the low octane fuel tank;
A knocking sensor;
A control device connected to the knocking sensor, the high octane fuel injector, and the low octane fuel injector;
When the knocking is detected, the control device performs control to increase the fuel injection ratio from the high octane fuel injector and retard the ignition timing.

  When the engine device according to the present invention detects knocking, it increases both the ratio of the high octane fuel and retards the ignition timing, so it does not supply excessive high octane fuel, and the retard is slight. Therefore, it is possible to achieve both an improvement in thermal efficiency and an improvement in fuel consumption.

It is a figure which shows the structure of the engine apparatus which concerns on this invention. It is a figure which shows the processing flow of a control apparatus. It is a figure which shows knocking and ignition timing, and the injection ratio of a high octane fuel. It is a figure which shows the example of control of the fuel injection and ignition timing by the flow of FIG. It is a figure which shows knocking, ignition timing, and the injection ratio of a high octane fuel when the engine apparatus which concerns on this invention is controlled by the other control method.

  The structure of the exhaust pipe according to the present invention will be described below with reference to the drawings. The following description exemplifies an embodiment of the present invention, and changes within the scope of the present invention are included in the technical scope of the present invention without departing from the spirit of the present invention. Needless to say.

  In FIG. 1, the outline | summary of the engine apparatus 1 of this invention is shown. The engine body 10 is a normal reciprocating engine, and includes a cylinder head 12, a cylinder block (not shown), an oil pan (not shown), a head cover (not shown), and the like. In FIG. 1, in the cylinder head 12, a part of the intake port 12in, the combustion chamber 12rm, and the exhaust port 12ex is shown.

  Members such as an intake manifold, a surge tank, a throttle body, and an air cleaner (not shown) are sequentially connected to the intake port 12in. In addition, components such as an exhaust manifold, a catalytic converter, and a silencer (not shown) are sequentially connected to the exhaust port 12ex. Further, a turbocharger using an intake system and an exhaust system may be added.

  Two systems of fuel injectors (also referred to as “injections”) are prepared for the intake port 12in. One is a high octane fuel injector 21 and the other is a low octane fuel injector 22.

  Each of the fuel injectors 21 and 22 is connected to a delivery pipe 23 for high octane fuel and a delivery pipe 24 for low octane fuel, respectively. Each delivery pipe 23, 24 is connected to a high-octane fuel tank 25 and a low-octane fuel tank 26. Therefore, in the engine device 1 according to the present invention, two types of fuels, a high octane fuel and a low octane fuel, are mounted.

  The two types of fuel may be so-called high-octane gasoline (unleaded premium gasoline) and regular gasoline. Each octane number is 90 to 91 for regular gasoline (low octane fuel), and 98 to 100 for high-octane gasoline (high octane fuel).

  In addition, the octane number referred to in this specification assumes a research octane number (Research Octane Number). However, it may be a motor octane number (MON) or an anti-knock index (AKI). Moreover, the engine apparatus 1 which concerns on this invention does not exclude a diesel engine. When the present invention is applied to a diesel engine, the octane number may be read as cetane number.

  The high-octane fuel injector 21 and the low-octane fuel injector 22 are connected to the control device 30. In addition, at least a knock sensor 32 and an ignition device 34 are connected to the control device 30. Further, an accelerator opening sensor 36, a speed sensor 37, a rotation speed sensor 38, and an angle sensor 39 may be connected to the control device 30.

  The control device 30 may be shared by an ECU (Engine Control Unit), or may be a computer using a separate MPU (Micro Processor Unit) and memory.

  Control device 30 receives signal Snk indicating the magnitude of knocking from knock sensor 32. Further, a signal Sac indicating the accelerator opening from the accelerator opening sensor 36, a signal Sv indicating the speed of the vehicle body from the speed sensor 37, a signal Srv indicating the engine speed from the rotation speed sensor 38, and an angle sensor 39 from the angle sensor 39. The signal Sθ indicating the angle of the crankshaft is received.

  In addition, the control device 30 transmits instructions Ch and Cr indicating the amount of fuel to be injected to the high-octane fuel injector 21 and the low-octane fuel injector 22 at the timing of injecting the fuel. In response to the instruction signals Ch and Cr, the high-octane fuel injector 21 and the low-octane fuel injector 22 inject the indicated amount of fuel.

  Furthermore, the control device 30 transmits Ci that instructs the ignition timing to the ignition device 34. The control device 30 receives a signal Sθ representing an angle from the reference position of the crankshaft from the angle sensor 39. Therefore, the control device 30 can know the current position of the piston. Therefore, the ignition timing is indicated by the crankshaft angle. When the ignition device 34 receives the signal Ci instructing the ignition timing, the ignition device 34 ignites the spark plug 27 in the combustion chamber 12rm.

  Operation | movement of the engine apparatus 1 which concerns on this invention which has the above structure is demonstrated. During normal driving, only low-octane fuel is supplied. At this time, the ignition timing is set to an advance angle so that the engine body 10 can exhibit the most output. By doing so, the amount of fuel used can be reduced.

  On the other hand, when the engine load increases due to a steep uphill or the like, knocking is likely to occur. If knocking occurs, the ignition timing is slightly retarded and high-octane fuel is injected. By doing so, knocking is suppressed, and at the same time, fuel consumption deterioration due to retardation and excessive injection of high-octane fuel are suppressed low.

  A description will be given with a more specific example. FIG. 2 shows a processing flow of the control device 30. The fuel injection is adjusted every time by the control device 30 by checking the presence or absence of knocking. Now, let Qr be the injection amount of the low octane fuel, Qh be the injection amount of the high octane fuel, and Qa be the total fuel injection amount. Of course, Qa = Qr + Qh.

Further, the injection ratio of the high octane fuel is γ. Therefore, the injection amount Qh of the high octane fuel is proportional to the retard angle AK that retards the ignition timing. For example, equations (1) and (2) are used.
Qh = Qa × (γ _k + γ _k−1 ) (1)
γ _k = α × (AK−β) (2)

Here, γ _k is the current minute time, and γ _k-1 represents the minute time immediately before. The minute time is a time determined by the machine time of the control device 30. That is, the injection amount Qh of the high octane fuel is the sum of the injection ratio of the high octane fuel determined from the current knocking strength and the previous injection ratio of the high octane fuel. The injection ratio γ of high octane fuel can be negative.

Α is a proportionality constant, and β is an offset constant. For example, α = 0.1 and β is 2 degrees. Then, AK = 0 when the ignition timing is not delayed. When the ignition timing is not retarded, AK = 0 continues and (γ _k + γ _k−1 ) in the equation ( ₁ ) becomes a negative value. Then, the expression (1) becomes a negative value as a whole. Since the injection amount Qh of the high octane number fuel cannot have a negative value, the injection is not performed. In other words, high-octane fuel is not injected when not retarded. In this case, the ignition timing is performed at or near the optimum ignition timing (MBT: Minimum Spark Advance for Best Torque).

  FIG. 3 shows the relationship between the knocking intensity, the ignition timing, and the injection ratio of the high octane fuel. The horizontal axis is the knocking strength (no unit), and the knocking strength is higher toward the right. The right vertical axis shows the ignition timing. The upper part of the axis represents the advance angle. MBT is the optimum ignition timing. When knocking is recognized (point A), the ignition timing is retarded according to the magnitude of knocking (inclination B). In this case, as shown by the equation (2), the high-octane fuel is not injected until a certain delay angle. This is the offset amount β. However, when the retard angle exceeds β, which is the offset amount, high octane fuel corresponding to the retard amount AK is injected (inclination C).

  That is, knocking is eliminated by two means of retarding and high-octane fuel injection. If knocking decreases, retard and high octane fuel injection will decrease accordingly. Moreover, it can be said that such control suppresses small knocking only by retarding the ignition timing, and suppresses large knocking by ignition timing and high-octane fuel injection.

  Referring to FIG. 2 again, when the process is disclosed (step S100), initial setting is performed (step S102). Here, the initial setting is an initial value of each parameter. When the process is started, an end determination is made (step S104). The end determination can be made in a situation where the engine is stopped. Of course, it may be caused by the ignition switch being turned off. When the process ends (Y branch in step S104), the process stops (step S105).

When the process continues (N branch in step S104), the knocking amount is detected (step S106). Control device 30 receives signal Snk from knock sensor 32 and knows its magnitude. Then, the retard amount AK is determined according to a predetermined table (step S108), and the ignition timing is delayed. When the retardation amount AK is determined, the injection amount ratio γ _k of the high octane fuel is obtained from the equation (2). Assuming that the retardation amount AK is 5 degrees, γ _k is 0.3 in the equation (2). The injection ratio γ of the high octane fuel is obtained as the sum of the previous injection ratio γ _k-1 and γ _k (step S112).

  Next, the injection amount Qh of the high octane fuel and the injection amount Qr of the low octane fuel are obtained based on γ (step S114). The total fuel injection amount Qa can be determined by a signal Sac from the accelerator opening sensor 36. Further, the injection amount Qr of the low octane fuel can be obtained by Qr = Qa−Qh.

  Therefore, the injection amount Qh of the high octane fuel and the injection amount Qr of the low octane fuel can be obtained immediately. Then, it is determined whether or not the injection amount Qh of the high octane fuel is negative (step S116). If the high octane number injection amount Qh is zero or negative, the high octane number fuel is not injected, and the low octane number fuel is injected by the total fuel injection amount Qa (step S122).

Injection instructions Ch and Cr corresponding to these injection amounts are sent from the control device 30 to the high-octane fuel injector 21 and the low-octane fuel injector 22 (step S118 or step S122). Finally, the current injection ratio γ _k of the high octane fuel is replaced with γ _k−1 (step S120). Then, the process returns to the end determination (step S104).

  Next, actual control according to the flow of FIG. 2 will be described. FIG. 4 shows the engine load, ignition timing, high octane fuel injection amount and time axis. In the region EL where the engine load is low, the ignition timing is performed in the vicinity of MBT. In this case, high-octane fuel is not injected (the injection ratio according to equation (2) is zero: F0 point).

  Assume that the engine load starts to increase and the ignition timing is set to the retard side (LI point). Since the retard amount AK at this time exceeds the offset amount β (AK1 point), the injection ratio γ of the high octane fuel is obtained and injected (F1 point).

At the next timing, the retard amount AK is advanced by a predetermined amount (AK2 point). As a result, the injection ratio γ _k of the high octane fuel is obtained from the equation (2), added to the previous injection ratio γ _k −1 of the high octane fuel, and the high octane fuel injection continues (point F2).

  The ignition timing is advanced to the advance side by a predetermined amount. If the ignition timing is advanced too much, knocking increases. At this time, the retard of the ignition timing advances again (AK3 point). At this time, since the injection of the high octane fuel continues, a smaller amount of retardation is required than the initial retardation (F3).

If the injection of high octane fuel increases, knocking does not increase even if the ignition timing advances to the advance side, and the ignition timing advances further to the advance side than the offset amount β (AK4 point). At this time, since γ _k is a negative value from the equation (2), the injection amount of the high-octane fuel is negative. As a result, the injection amount Qh of the high-octane fuel decreases (F4 point).

  However, since the injection amount Qh of high octane fuel is integrated, it does not become zero suddenly even if the ignition timing is brought close to MBT. As described above, when the control in the flow of FIG. 2 is performed, in order to prevent knocking while changing both the ignition timing and the high octane fuel, the ignition timing is advanced as much as possible without using a large amount of high octane fuel. Can be done on the corner side.

  FIG. 5 shows another control principle of the engine apparatus 1 according to the present invention corresponding to FIG. The horizontal axis is the knocking intensity, the right vertical axis is the ignition timing, and the left vertical axis is the ratio of the injection amount of the high octane fuel. The meaning of the axis is the same as in FIG. In the example of FIG. 5, the offset amount β is changed depending on the knocking strength. The offset amount β is a factor that suppresses the injection amount of the high-octane fuel, and determines the control range only by retarding the ignition timing when knocking is small. That is, while the retard amount AK does not exceed the offset amount β, knocking is suppressed only by retarding the ignition timing, and high-octane fuel is not injected.

  However, once the high-octane fuel is injected by setting the compression ratio, it may be more effective to inject a certain amount of octane fuel. FIG. 5 shows an example in which the offset amount β is reduced in the region (inclination C) where AK exceeds the offset amount β and high-octane fuel is injected. Specifically, at the point where the knocking strength is W, the offset amount β is set small.

  As a result, the injection ratio of the high octane fuel is increased from the equation (2) (inclination D). The offset amount β may be changed by a plurality of values, and the degree of freedom in engine design can be increased, and the thermal efficiency engine output and fuel consumption can be reduced more finely. The processing flow by the control device 30 may be the processing shown in FIG.

  The present invention can be suitably used for automobile engine devices, and in particular, can be used for automobiles capable of mounting two types of fuel, so-called high-octane gasoline and regular gasoline.

DESCRIPTION OF SYMBOLS 1 Engine apparatus 10 Engine main body 12 Cylinder head 12in Intake port 12rm Combustion chamber 12ex Exhaust port 21 High octane fuel injector 22 Low octane fuel injector 23 High octane fuel delivery pipe 24 Low octane fuel delivery pipe 25 High octane fuel tank 26 Fuel tank for low octane number 27 Spark plug 30 Control device 32 Knock sensor 34 Ignition device 36 Accelerator opening sensor 37 Speed sensor 38 Rotational speed sensor 39 Angle sensor Sac Accelerator opening signal Snk Knocking signal Sv Speed signal Srv Rotational speed signal Sθ Crank angle Ch High-octane fuel injection instruction Cr Low-octane fuel injection instruction Ci Ignition timing instruction

Claims (1)

A high-octane fuel tank,
A low octane fuel tank,
A high octane fuel injector in communication with the high octane fuel tank;
A low octane fuel injector in communication with the low octane fuel tank;
A knocking sensor;
A control device connected to the knocking sensor, the high octane fuel injector, and the low octane fuel injector;
When the knocking is detected, the control device performs control to increase the fuel injection ratio from the high-octane fuel injector and retard the ignition timing.