JPH0338413B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder number control device for a three-cylinder engine.

Conventionally, in order to improve fuel efficiency in multi-cylinder engines, engines with cylinder number control have cut off the fuel supply to some cylinders during light loads, halting the operation of those cylinders, and performing cylinder reduction operation. Are known.
Generally, such cylinder number control engines target even number cylinder engines such as 4 cylinders or 6 cylinders,
As seen in Japanese Unexamined Patent Publication No. 56-2430, in order to maintain smooth operating conditions even during cylinder reduction operation, a specific part (half) of the cylinders in which the ignition order is not consecutive are used during cylinder reduction operation. One cylinder is inactive, and the other cylinders are always in operation. During reduced-cylinder operation, the fuel supply to the specific cylinder inactive is cut off to stop the operation (explosive combustion) of the cylinder. However, in this structure where a specific cylinder continues to be deactivated during cylinder reduction operation, the temperature inside the deactivated cylinder decreases during the cylinder reduction operation period, so when the cylinder is switched to full cylinder operation, This has resulted in adverse effects such as poor combustibility, increased unburned gas emissions, and unstable torque fluctuations.

In view of these circumstances, the present invention targets a three-cylinder engine and performs reduced-cylinder operation while maintaining smooth engine operation under light load, and prevents a temperature drop in a specific cylinder during reduced-cylinder operation. The present invention provides a cylinder number control device that can improve combustibility during subsequent transition to all-cylinder operation.

That is, in the present invention, the crank arms are connected to each other.
In a three-cylinder engine arranged at 120° intervals, a light load detection means for detecting a light load operating range of the engine, and stopping each explosion combustion operation in each cylinder once at a light load, and cylinder stopping means for ensuring that explosive combustion of the engine is carried out at regular intervals at constant crank angles; Valve mechanism stopping means shuts off the intake air into each cylinder every other time by stopping one of the valve mechanisms; and a control means for controlling the valve mechanism stop means.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a three-cylinder engine, in which 1 is the engine body, 2 is an intake manifold, 3 is an exhaust manifold, and 4 is a carburetor.
The engine body 1 has three cylinders 11, 12,
13, and the crank arms (not shown) of the corresponding crankshafts are arranged at 120° intervals from each other. Accordingly, each cylinder 11, 1
Ignition at points 2 and 13 is performed at intervals of a constant crank angle. In other words, in the case of a four-stroke engine in which one cycle is performed with two revolutions of the crankshaft, each cylinder 11,
Ignition at 12 and 13 takes place.

Figure 2 shows the specific structure of the cylinder number control device.
In the figure, 20 is a load sensor as light load detection means, 21 is a control circuit that receives a signal from the load sensor 20, and the load sensor 20 is, for example, a negative pressure sensor that detects negative pressure in the intake passage. The control circuit 21 generates an activation signal for cylinder reduction operation in response to a signal from the load sensor 20 when the load is light below the set load. Also,
A valve mechanism stopping means 60 is provided which operates in response to this activation signal, and this valve mechanism stopping means 60 and the control circuit (control means) 21 control the operation of explosion and combustion in each cylinder during light loads. 1
Cylinder stopping means is configured to stop the engine at regular intervals and to cause explosion combustion of the engine to occur at regular intervals at constant crank angles. The valve train stopping means 60 controls one of the valve train mechanisms 40 of the pair of valve train mechanisms 30 and 40, each of which is responsible for half the number of operations of the intake valves 15 of each cylinder 11, 12, 13. It was designed to stop it.

The above-mentioned pair of valve mechanisms 30 and 40 are shown in FIGS. 2 and 3.
The structure is as shown in Fig. 4. That is,
Both valve mechanisms 30 and 40 are connected to the camshaft 3 separately.
1,41. Each camshaft 31, 4
1 is a pulley 51, 52 provided at each end.
and a timing belt 54 and idlers 55, 5, which are stretched over a pulley 53 provided on the crankshaft.
It is continuously connected to the crankshaft at a rotation ratio of 1/4 via a transmission mechanism 50 consisting of 6 parts. Each cylinder 1 is connected to both camshafts 31 and 41, respectively.
Intake valve cams 32..., 42... for operating the intake valves 15... 1, 12, 13 are provided, and a pair of rocker arms 33..., 43... is in place. This pair of Rotsuka arms 33, 43 are
Both tips are in contact with the tappet 16 disposed on the upper part of the intake valve 15, and the middle part is in contact with the cams 32 and 42 of each camshaft 31 and 41, and the base of the rocker arm 33 on the left side in FIG. It is supported by a support part 34 fixedly provided on the head 17, and the base of the right rocker arm 43 is supported by a support part 65 whose supporting force can be released, which will be described later. As long as the valve mechanism stopping means 60 does not operate, the cams 32 and 42 are activated once for each rotation of the camshafts 31 and 41 (two engine operating cycles) for one intake valve 15, and The intake valve 15 is opened by pushing the rocker arms 33 and 43, which are shifted from each other by half a rotation of the camshaft.

Furthermore, exhaust valve cams 35 for operating the exhaust valves 18 through rocker arms 36 are disposed on the camshaft 31 on one side, and the cams 35
has protrusions in two directions so that the exhaust valve 18 is opened twice for each rotation of the camshaft 31.

The valve mechanism stopping means 60 includes a fixed inner cylinder 62 that forms a lower oil chamber 61, a plunger 64 that is fitted onto the inner cylinder 62 and forms an upper oil chamber 63 above the inner cylinder 62, and a fixed inner cylinder 62 that forms a lower oil chamber 61. The plunger 64 has a rocker arm support portion 65 projecting from the upper end thereof, which is attached to the cylinder head 17. Both oil chambers 61 and 63 communicate with each other through a communication hole 66 provided at the upper end of the inner cylinder 62, and there is a check mark in the communication hole 66 that only allows oil to flow from the lower oil chamber 61 to the upper oil chamber 63. A valve 67 is provided. Further, the lower oil chamber 61 is connected to an oil pump 69 via an oil supply passage 68, and an on-off valve 70 is provided in the passage 68. On the other hand, the upper oil chamber 63 is
The other end is connected to an oil discharge passage 71 opened into the cylinder bed, and an on-off valve 72 and check valves 73, 74 are disposed in the passage 71.
When the load is light when cylinder reduction operation is to be performed, the on-off valve 70 in the oil supply passage 68 is closed and the on-off valve 72 in the oil discharge passage 71 is opened in response to an operation signal from the control circuit 21. At other times, the on-off valve 70 in the oil supply passage 68 is opened and the on-off valve 72 in the oil discharge passage 71 is closed. Reference numeral 75 denotes a spring compressed in the upper oil chamber 63, which urges the plunger 64 upward and elastically presses the rocker arm 43 against the cam 42, thereby bringing the tip of the rocker arm 43 into contact with the tappet 16. It is intended to maintain the However, the elastic force of the spring 75 is set smaller than the supporting force required to make the valve operating mechanism 40 substantially work.

According to this structure, the pair of valve mechanisms 3
0, 40, one valve mechanism 40 (on the right side in Figure 2) is substantially operated only when all cylinders should be operated, and the other valve mechanism 30 (on the left side in Figure 2) is always activated. It is operated in accordance with the rotation of the camshaft 31. That is, in an operating range in which all cylinders are operated such as medium load or high load, the on-off valve 70 and the on-off valve 72 in the valve train stop means 60 open and close, so that the oil supplied from the oil pump 69 is Check valve 6 from lower oil chamber 61
7 into the upper oil chamber 63 and is sealed within the oil chamber 63. In this state, the support part 65 at the upper end of the plunger 64 is held in the raised position by hydraulic pressure, and the rocker arm 43 swings up and down with the rotation of the cam 42 using this as a fulcrum to periodically open the intake valve 15. do. In other words, one of the valve train mechanisms 40 is substantially operated, and by this and the operation of the other valve train mechanism 30, the intake valve 15 is opened in the intake stroke for each cycle, and the air-fuel mixture is supplied to the combustion chamber. , all-cylinder operation is performed.

In addition, in a light load operating range, the on-off valve 70 in the valve mechanism stopping means 60 is closed and the on-off valve 72 is opened, so that the oil in the upper oil chamber 63 is discharged and the plunger holding force due to hydraulic pressure is removed. be done. In this state, when the rocker arm 43 is pushed by the cam 42, the support portion 65 descends;
It no longer functions as a fulcrum. Therefore, the operation of the one valve train mechanism 40 is substantially stopped, and the intake valve 15 is not opened by this valve train mechanism 40.
The intake valve 15 is opened only by the operation of the other valve operating mechanism 30.

In this way, during light loads, each cylinder 11, 12,
13, the operation of explosive combustion is stopped by cutting off the intake air (fuel supply) every other cycle, that is, operation and rest are alternately performed every cycle. In addition, each cylinder 11, 12, 1
3 are called the 1st, 2nd, and 3rd cylinders in the order of ignition, the engine as a whole will have 1st cylinder operating, 2nd cylinder deactivated, 3rd cylinder activated, 1st cylinder deactivated, 2nd cylinder activated, and 3rd cylinder. The engine is operated and stopped repeatedly in the order of stops, and cylinder reduction operation is performed while explosive combustion occurs at equal intervals. Therefore, uneven torque fluctuations can be avoided even during cylinder reduction operation, and temperature differences between the cylinders can also be avoided.

Note that as a method for reducing cylinder operation, there is a method in which only the supply of fuel is stopped (stopping fuel injection from the injector) to the cylinder to be deactivated, but as in the present invention, it is possible to stop the fuel supply to the combustion chamber by stopping the valve. Blocking the inflow of intake air is more advantageous in terms of reducing pumping loss, etc. In a three-cylinder engine, a pair of valve mechanisms 30 and 40 are provided for the intake valves of each cylinder, and by stopping one of the valve mechanisms 40, the above-mentioned alternate operation of each cylinder is performed. Valve stop is achieved with a relatively simple construction.

As described above, the device of the present invention can
In a three-cylinder engine, the operation of explosive combustion in each cylinder is stopped once at intervals, and the engine's explosive combustion is carried out at regular intervals at constant crank angles, making it possible to reduce the number of cylinders during light load operation. In addition to being carried out smoothly, a specific cylinder does not continue to stop even during reduced-cylinder operation, which prevents a drop in cylinder temperature, and improves combustion performance even when transitioning to full-cylinder operation. . In addition, in particular, by stopping one of the pair of valve mechanisms, each of which is responsible for half the number of times the intake valves in each cylinder operate, the inflow of intake air into each cylinder can be reduced by one.
Since the cylinder stopping means is composed of the valve train stopping means that shuts off every other cycle and the control means, the cylinder stopping means is advantageous for reducing pumping loss, etc., and the cylinder reduction operation in which the valves are stopped alternately as described above is possible. , which can be achieved with a relatively simple structure.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a three-cylinder engine, Fig. 2 is a sectional view showing an embodiment of the device of the present invention, Fig. 3 is a schematic perspective view of the valve mechanism, and Fig. 4 is a diagram showing the relationship between the crankshaft and the valve mechanism. FIG. 1... Engine body, 11, 12, 13... Cylinder, 20... Load sensor, 30, 40... Valve mechanism, 60... Valve mechanism stopping means (cylinder stopping means).

Claims (1)

[Claims] 1. In a three-cylinder engine in which the crank arms are arranged at 120° intervals from each other, a light load detection means for detecting the light load operating range of the engine, and a light load detection means for detecting the operation of explosion combustion in each cylinder at light load.
cylinder stopping means for stopping the engine at regular intervals, and for causing explosion combustion of the engine to occur at regular intervals at constant crank angles, the cylinder stopping means:
An operation that shuts off the inflow of intake air to each cylinder every other time by stopping one of a pair of valve operating mechanisms that is responsible for half the number of times the intake valves of each cylinder operate. A cylinder number control device for a three-cylinder engine, comprising a valve mechanism stopping means and a control means for controlling the valve mechanism stopping means in response to a signal from the light load detecting means.