JP2007198263A - Engine ignition device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize both the elongation of service life of a spark plug and improvement on its ignition performance in an engine required to have a long-time durability (for instance, the engine used in an engine-powered heat pump). <P>SOLUTION: An engine 30 having a plurality of spark plugs 10, 20 per cylinder, is equipped with a type (A) spark plug 10 with a prescribed space of air gap and a type B spark plug 20 with a space of air gap different from the air gap of the type (A) spark plug 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ignition device technology for an engine in which a plurality of spark plugs are arranged in one cylinder.

Conventionally, a spark plug provided in an engine is well known. A spark plug is an ignition device that ignites a fuel in a cylinder by sparks. For example, Patent Document 1 discloses a gas engine having a spark plug at the top of a cylinder in a cylinder.
JP 2004-293344 A

  Here, a spark plug ignition method will be described. First, the voltage is amplified to several thousand volts with an ignition coil or the like. Further, the amplified voltage is applied to the center electrode and the ground electrode to generate an electric spark (flying fire). The fuel particles between the electrodes are activated by spark discharge and cause a chemical reaction (oxidation). Generation of this reaction heat creates flame nuclei (ignition), and combustion spreads to the surroundings.

  A gap (hereinafter referred to as an air gap) between the center electrode and the ground electrode to which the amplified voltage is applied greatly affects the performance of the spark plug. For example, a spark plug with a wide air gap requires a large voltage (required voltage), and the electrodes are easily consumed. On the other hand, a spark plug with a narrow air gap has the performance of being difficult to ignite.

An engine that requires long-term durability (for example, an engine used in an engine-driven heat pump) uses a spark plug that has a narrow air gap in consideration of electrode consumption. However, generally, a spark plug with a narrow air gap is inferior in ignition performance to a spark plug with a wide air gap.
Therefore, a problem to be solved is to provide an engine that can achieve both a long life of a spark plug and an improvement in ignition performance.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, in an engine in which a plurality of spark plugs are arranged in one cylinder, a first spark plug having an air gap of a predetermined interval and an air gap having an interval different from the air gap of the first spark plug. With a second spark plug.

  According to a second aspect of the present invention, in the engine according to the first aspect, a rotational speed detecting means for detecting the rotational speed of the engine, and a storage means for storing a relationship between the rotational speed and a spark plug used for each rotational speed. A control means for connecting the rotational speed detection means and the storage means, and for controlling the ignition of the two spark plugs by selecting the first spark plug or the second spark plug according to the rotational speed of the engine; It is.

  According to a third aspect of the present invention, in the engine according to the first aspect, load detecting means for detecting a load of the engine, storage means for storing a relationship between the load and a spark plug used for each load, and the load detection And means for controlling the two spark plugs to select and ignite the first spark plug or the second spark plug according to the engine load.

  According to a fourth aspect of the present invention, the engine according to the second or third aspect is provided with a rewriting means for connecting the rotation speed detecting means to the control means and capable of rewriting the contents of the storage means when an ignition failure occurs. It is.

  According to a fifth aspect of the present invention, in the engine according to the first to fourth aspects, the engine has a plurality of cylinders, and the two spark plugs are controlled for each cylinder.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect of the present invention, by providing two spark plugs in one cylinder, electrode wear of the spark plug is reduced. That is, the life of the spark plug can be extended.

  According to the second aspect, in addition to the effect of the first aspect, by selecting a spark plug corresponding to the engine speed, it is possible to achieve both ignition failure and reduction of electrode wear. That is, the engine can be operated efficiently.

  In the third aspect, in addition to the effect of the first aspect, by selecting a spark plug corresponding to the load of the engine, both ignition failure and reduction of electrode wear can be achieved. That is, the engine can be operated efficiently.

  In claim 4, in addition to the effect of claim 2 or 3, when the years of use of the engine have elapsed, a spark plug suitable for the required voltage accompanying the electrode consumption of the spark plug can be selected, and ignition failure and electrode wear are reduced. Can be achieved. That is, the engine can be operated efficiently.

  According to the fifth aspect, in addition to the effects of the first to fourth aspects, the spark plug suitable for each cylinder of the engine can be selected and operated, and electrode wear can be reduced.

Next, embodiments of the invention will be described.
FIG. 1 is a schematic diagram showing an internal structure of an engine having two spark plugs according to the present invention, FIG. 2 is a control circuit diagram showing the configuration of the ignition device, and FIG. 3 is a refrigerant showing the overall configuration of the engine-driven heat pump. It is a circuit diagram.
4 is a table showing the engine speed / load map, FIG. 5 is a flowchart showing the spark plug change control, and FIG. 6 is a table showing the first rewriting means for the engine speed / load map. is there.
FIG. 7 is a table showing the second rewriting means.

  An embodiment of the present invention is an engine 30 used for an engine-driven heat pump 50. In this engine-driven heat pump 50, the engine 30 drives a compressor 51.

  The engine 30 of the present embodiment is a gas engine that uses a gaseous fuel such as natural gas. First, the internal structure of the cylinder in the engine 30 will be described. In the present embodiment, the number of cylinders of the engine 30 is not limited. In the multi-cylinder engine, the number of cylinders having the internal structure shown in the present embodiment is assumed to exist.

As shown in FIG. 1, the combustion chamber 36 is a space for burning the mixed gas, and communicates with an intake pipe (intake manifold) 31 and an exhaust pipe (exhaust manifold) 32. The combustion chamber 36 is formed by a cylinder in which a space is formed in an upper part of a cylinder block 35 that is a member constituting the structure of the engine 30 and a cylinder head 39 disposed in the upper part. A piston 33 that reciprocates by sliding in an airtight manner is provided in the cylinder.
The piston 33 slides downward (in which the volume of the combustion chamber 36 increases) as the mixed gas supplied to the combustion chamber 36 burns and expands. Further, a crankshaft 34 is connected to the piston 33 via a connecting rod, and the crankshaft 34 rotates by the reciprocating motion of the piston 33.

Similarly, as shown in FIG. 1, the intake pipe 31 is a pipe that takes in air from the outside and supplies a mixed gas generated by mixing the air and fuel with a mixer (not shown) to the engine 30. An air cleaner (not shown) is provided at one end of the intake pipe 31 in order to remove dust and the like in the air introduced into the intake pipe 31. On the other hand, the other end of the intake pipe 31 is connected to the intake port of the cylinder head 39 of the engine 30.
The intake valve 37 is provided in the middle of the intake port and the combustion chamber 36 in the cylinder head 39. The intake valve 37 is a valve that communicates or closes the intake pipe 31 and the combustion chamber 36 by opening and closing the intake port.

Similarly, as shown in FIG. 1, the exhaust pipe 32 is a pipe for discharging the exhaust gas generated by combustion of the mixed gas in the combustion chamber 36 to the outside of the engine 30. One end of the exhaust pipe 32 is connected to the cylinder head 39 of the engine 30. On the other hand, the other end is connected to a muffler (not shown).
The exhaust valve 38 is provided in the middle of the exhaust port and the combustion chamber 36 in the cylinder head 39. The exhaust valve 38 is a valve that communicates or closes the exhaust pipe 32 and the combustion chamber 36 by opening and closing the exhaust port.
The intake valve 37 and the exhaust valve 38 are driven up and down by valve arms that are linked to the crankshaft via cams, rods and the like.

Similarly, as shown in FIG. 1, the engine 30 includes two spark plugs 10 and 20 in the combustion chamber 36.
The spark plugs 10, 20 are provided on the cylinder head 39, and their tip portions are disposed inside the combustion chamber 36. The spark plugs 10 and 20 burn the mixed gas supplied to the combustion chamber 36 by generating sparks.
In this embodiment, the two spark plugs 10 and 20 are spark plugs having different air gaps. Specifically, the air gap of the A-type (first) spark plug 10 is narrower than the air gap of the B-type (second) spark plug 20.
However, three or more spark plugs can be provided. In this case, the air gaps of the spark plugs are different from each other, and the spark plugs are selected and sparked according to the rotational speed and load. By doing so, the engine can be operated more efficiently and the life of the spark plug can be extended.
The air gap is a gap between the center electrode and the ground electrode to which the amplified voltage is applied. This air gap greatly affects the performance of the spark plug. A spark plug with a wide air gap has a large required voltage (required voltage), and has a performance that the electrode is easily consumed. On the other hand, a spark plug with a narrow air gap has a small required voltage and has a performance that the electrode is not easily consumed. Furthermore, the A-type spark plug 10 is inferior in ignition performance to the B-type spark plug 20.

  In this embodiment, the heat value of the A-type spark plug 10 having poor ignition performance is set to a low heat value type (burning type). The heat value is a numerical value indicating the heat dissipation degree of the spark plug. Since the low heat value type spark plug is difficult to dissipate heat and the electrode part is easily burnt, it is suitable for use in an engine region having a low load and a low rotational speed.

As shown in FIG. 2, an engine control unit (hereinafter abbreviated as ECU) 60 is connected to an ignition device 40 provided in the engine 30. The ECU 60 is a control unit, and includes an arithmetic device, a storage unit, and the like. In the ignition device 40, the A-type spark plug 10 and the B-type spark plug 20 are arranged as independent circuits 14 and 24, respectively.
The ignition device 40 includes an igniter 41, ignition coils 13 and 23, and spark plugs 10 and 20, and is a device supplied with power from a battery 43.
The igniter 41 is an electronic device that determines the ignition timing of the spark plugs 10 and 20, and is a kind of switch using a semiconductor. In the present embodiment, the switching device 42 is disposed on the secondary side of the igniter 41. The switch 42 is connected to the ECU 60 and can switch between the circuit 14 and the circuit 24.
The ignition coils 13 and 23 are a kind of transformer that generates a high voltage necessary for ignition. The ignition coils 13 and 23 are provided in respective circuits in the first spark plug 10 and the second varnish spark plug 20. The spark plugs 10 and 20 apply a voltage amplified to several thousand volts by the ignition coils 13 and 23 of the respective circuits to the center electrodes 11 and 21 and the ground electrodes 12 and 22 to generate electric sparks.
In the case where the engine 30 is a multi-cylinder engine, an ignition device 40 is provided for each cylinder, and the first spark plug 10 or the second varnish spark plug 20 is provided by the control means 60 according to the rotational speed or load for each cylinder. Is selected and sparked. In this way, even if there is variation among cylinders, it is possible to reliably burn. However, it is also possible to use a distributor (not shown). This distributor is a power distribution mechanism that sequentially distributes the generated high voltage to the spark plugs of each cylinder in accordance with the ignition sequence.

Since the center electrode of the spark plug becomes high temperature, it is oxidized and consumed. For this reason, periodic inspection and replacement of spark plugs has been essential. By using the two spark plugs 10 and 20 in one cylinder as in this embodiment, the amount of spark plug used is halved. That is, the life of the spark plug can be extended.
Further, by using the two spark plugs 10 and 20 having different air gaps, that is, different performances in ignition performance and electrode wear, it is possible to reduce electrode wear and improve ignition performance.
Further, the ignition performance can be further improved by reducing the heat value of the A-type spark plug 10 having a narrow air gap.

As shown in FIG. 3, the engine-driven heat pump 50 includes a compressor 51 that is driven by the engine 30. The compressor 51 performs cooling and heating by circulating a refrigerant.
Intermittent motive power from driving the engine 30 to the compressor 51, that is, switching between operation and stop of the compressor 51, is interposed between a drive pulley (not shown) of the compressor 51 and a drive shaft of the compressor 51. This is done by turning the clutch 52 on and off. In this embodiment, the clutch 52 is an electromagnetic clutch having a known configuration. The waste heat of the engine 30 is cooled by circulating cooling water, and this cooling water is cooled by a radiator (not shown) and the waste heat recovery unit 53.

Similarly, as shown in FIG. 3, the configuration of the engine-driven heat pump 50 will be briefly described.
The engine-driven heat pump 50 is connected to a compressor 51, a four-way valve 54 that is connected to the discharge side of the compressor 51 and switches the flow of refrigerant during cooling and heating, and from the compressor 51 through a four-way valve 54 during cooling. An outdoor heat exchanger 55 to which the refrigerant is supplied, an indoor heat exchanger 56 to which the refrigerant is supplied from the compressor 51 via the four-way valve 54 during heating, and the outdoor heat exchanger 55 and the indoor heat exchanger 56 are arranged. It has an outdoor expansion valve 57 provided, and is a refrigerant cycle composed of these.

Similarly, as shown in FIG. 3, the ECU 60 is connected to a suction pressure sensor 61 and a discharge pressure sensor 62. The suction pressure sensor 61 and the discharge pressure sensor 62 are provided in the suction path 58 and the discharge path 59, respectively. Here, the ECU 60 determines the pressure difference of the compressor 51 obtained by subtracting the suction pressure detected by the suction pressure sensor 61 from the discharge pressure detected by the discharge pressure sensor 62 as the load of the engine 30. However, the load detection is not limited to this configuration, and it is also possible to calculate from the engine speed and the throttle position.
The ECU 60 is connected to a rotational speed detector 63 that detects the rotational speed of the engine 30. Further, the ECU 60 is connected to the ignition device 40. Here, the ECU 60 selects the spark plugs 10 and 20 to be ignited by the ignition timing of the ignition device 40 and the switch 42.

As shown in FIG. 4, the ECU 60 stores a map 70 in which the load and rotation speed of the engine 30 are arranged. In this map 70, the ECU 60 selects the optimum spark plugs 10 and 20 from the detected load and rotation speed of the engine 30.
In the map 70, the vertical axis represents the engine load, that is, the pressure difference of the compressor 51, and the horizontal axis represents the engine speed. The engine load is divided into 10 regions from 0 MPa to 4.0 MPa. Here, for example, the region of 0.8 MPa includes a range of 0.6 MPa or more and less than 1.0 MPa. The engine speed is divided into 10 regions from 1000 rpm to 2000 rpm. Here, for example, the region of 1600 rpm includes a range of 1500 rpm or more and less than 1700 rpm. Note that the arrangement of the map 70 is not limited to the present embodiment.

Similarly, as shown in FIG. 4, in the map 70, A indicates a region where the A-type spark plug 10 with a narrow air gap is used, and B indicates a region where the B-type spark plug 20 with a wide air gap is used.
In an area where the engine 30 is at a low speed and a low load (upper left portion in the map 70), the A-type spark plug 10 is used which has poor ignition performance but low electrode consumption. On the other hand, in a region where the engine 30 is at a high rotation speed and a high load (lower right portion in the map 70), the B-type spark plug 20 having a large ignition consumption but a good ignition performance is used. Also, the B-type spark plug 20 having good ignition performance can be used even in the case of low rotation and high load.
Here, a region boundary where the A-type spark plug 10 and the B-type spark plug 20 are used is configured as a diagonal line rising to the right on the map 70. Here, a diagonal line indicating a boundary, that is, a use limit region row on the B-type spark plug 10 side is defined as a row N.

  Thus, by selecting the optimal spark plug according to the rotation speed and load of the engine 30, it is possible to achieve both reduction in ignition failure and reduction in electrode wear. In this embodiment, the advantage that the A-type air gap 10 is resistant to electrode wear and the advantage that the B-type air gap 20 has good ignition performance can be properly used. That is, the engine 30 can be operated efficiently from the viewpoints of durability and ignitability.

As shown in FIG. 5, the misfire improvement control using the map 70 will be described. In order to simplify the description, it is assumed that the A-type spark plug 10 is initially used.
First, in S100, the engine 30 is operated with the optimal A-type spark plug 10 derived from the rotation speed and the load on the map 70. Here, in S101, the ECU 60 performs misfire determination of the A-type spark plug 10. If the A-type spark plug 10 is ignited without any problem, the normal operation of S100 is resumed. On the other hand, if the A-type spark plug 10 misfires, the process proceeds to S102.
Next, in S102, the ECU 60 determines which spark plug 10 the misfired A-type spark plug 10 is (in this example, the A-type spark plug 10). In S103, the ECU 60 changes the spark plug to be used to a B-type spark plug 20 different from the misfired A-type spark plug 10.
Furthermore, in S104, if the B-type spark plug 20 is ignited without any problem, the process proceeds to S105. On the other hand, if the B-type spark plug 20 misfires, the process proceeds to S106. Here, in S106, since the ECU 60 misfires with the two spark plugs 10 and 20, it is determined as abnormal and warns the alarm.
In S105, the ECU 60 rewrites the map 70. Details of this rewriting will be described later.

  Thus, even if one spark plug misfires in the engine 30, the ignition performance of the engine 30 is improved by using the other spark plug. Moreover, when misfire occurs in each of the two spark plugs 10 and 20, it is determined that there is some abnormality, and the operator can be promptly inspected.

With reference to FIG. 6, the first rewriting means of the map 70 will be described in S <b> 106 of the misfire improvement control described above.
As shown in FIG. 6A, the region (α in the drawing) where the rotational speed is 1200 rpm and the load is 2.8 MPa is a region where the A-type spark plug 10 is used from the map 70. When a misfire occurs in this region, the B-type spark plug 20 is ignited by the misfire improvement control described above.
At the same time, the map 70 is rewritten so that the spark plug used in the region α becomes the B-type spark plug 20. That is, the column N is changed to a column including the region α. That is, as shown in FIG. 6B, two areas are rewritten from A to B in each item string of each engine speed.

  Generally, when the engine load is high, the required voltage of the spark plug is high. When the engine has been used for a long time, the required voltage increases as the spark plug electrode is consumed. In such a case, by reducing the area where the A-type spark plug 10 is used and expanding the area where the B-type spark plug 20 is used, it is possible to achieve both ignition failure and reduction in electrode wear.

The second rewriting means will be described with reference to FIG. Since FIG. 7 (a) is in the same state as FIG. 6 (a), description thereof is omitted.
As shown in FIG. 7B, when the engine 30 misfires with the A-type spark plug 10, it is ignited with the B-type spark plug 20 by the misfire improvement control described above. At the same time, in the map 70, only one column is rewritten to the A side. That is, when misfire is caused by the A-type spark plug 10, the region where the B-type spark plug 20 with good ignition performance is used is expanded by changing the row N to the A side for one row from the present. In other words, one area is rewritten from A to B in each item string of each engine speed.

  In the second rewriting means, the change of the spark plug area to be used is made gentler than that of the first rewriting means. In this manner, an appropriate map 70 corresponding to the state of the two spark plugs 10 and 20 in the current engine 30 can be created. That is, it is possible to further improve both the ignition failure and the reduction of electrode wear.

The schematic diagram which shows the internal structure of the engine which has two spark plugs which concern on this invention. The control circuit diagram which similarly shows the structure of an ignition device. The refrigerant circuit figure which shows the whole structure of an engine drive type heat pump similarly. The table figure which similarly shows the engine speed / load map. The flowchart figure which similarly shows spark plug change control. The table figure which similarly shows the 1st rewriting means of the rotation speed / load map of an engine. The table figure which similarly shows a 2nd rewriting means.

Explanation of symbols

10 A-type spark plug 20 B-type spark plug 30 Engine

Claims (5)

In an engine in which a plurality of spark plugs are arranged in one cylinder,
A first spark plug having an air gap of a predetermined interval;
An engine comprising a second spark plug having an air gap having a different interval from the air gap of the first spark plug. The engine according to claim 1.
A rotational speed detection means for detecting the rotational speed of the engine;
Storage means for storing the relationship between the rotational speed and a spark plug used for each rotational speed;
Control means for connecting the rotational speed detection means and the storage means, and controlling the ignition of the two spark plugs by selecting the first spark plug or the second spark plug according to the rotational speed of the engine. A featured engine. The engine according to claim 1.
Load detecting means for detecting the load of the engine;
Storage means for storing a relationship between the load and a spark plug used for each load;
The load detecting means and the storage means are connected, and control means is provided for controlling ignition by selecting the first spark plug or the second spark plug according to the engine load of the two spark plugs. To engine. The engine according to claim 2 or 3,
Connecting the rotational speed detection means to the control means;
An engine comprising rewriting means capable of rewriting the contents of the storage means when ignition failure occurs. The engine according to any one of claims 1 to 4, wherein the engine has a plurality of cylinders, and the two spark plugs are controlled for each cylinder.

Images