JP2021120562A - Internal combustion engine - Google Patents

Abstract

To improve fuel consumption performance by stopping fuel injection and ignition combustion while keeping uniform interval of combustion without causing lowering of a cylinder temperature of a specified cylinder, degradation of performance of a catalyst for exhaust emission control, and the like.SOLUTION: An internal combustion engine includes an intake cam shaft and an exhaust cam shaft rotating one time every time a crank shaft rotates four times; a first intake cam and a first exhaust cam pivotally supported respectively by the intake cam shaft and the exhaust cam shaft, and each having two cam lobes of symmetrical shape across a shaft center of the intake cam shaft or the exhaust cam shaft; second intake cams and second exhaust cams pivotally supported respectively by the intake cam shaft and the exhaust cam shaft, and each having only one cam lobe; and a switching mechanism for allowing the first intake cam and the first exhaust cam to come into a first state of driving to open respectively an intake valve and an exhaust valve in a high load operation, and allowing the second intake cams and the second exhaust cams to come into a second state of driving to open respectively the intake valve and the exhaust valve in a low load operation.SELECTED DRAWING: Figure 7

Description

The present invention relates to an internal combustion engine mounted on a vehicle as a power source.

Conventionally, it has been known to suspend fuel injection and ignition combustion in a specific cylinder during low-load operation in order to further improve fuel efficiency.

However, if only fuel injection and ignition combustion in the target cylinder are stopped and the intake / exhaust valves are continuously opened and closed, air is sucked into the cylinder and discharged to the exhaust system, so that the combustion chamber temperature of the cylinder becomes high. It will drop significantly. Along with this, problems such as an increase in mechanical loss due to an increase in viscosity due to a decrease in engine oil temperature and a need to increase a fuel injection amount when returning to high-load operation occur. Further, when the air is discharged to the exhaust system as it is, an excessive amount of oxygen is adsorbed on the catalyst for exhaust gas purification, the temperature of the catalyst is lowered, and the NOx reduction performance is deteriorated. ..

Therefore, as in the internal combustion engine disclosed in Non-Patent Document 1 below, not only fuel injection and ignition combustion but also opening and closing of intake / exhaust valves are suspended in a specific cylinder. By doing so, it is possible to prevent air from being introduced into the cylinder, and it is possible to suppress the occurrence of the above-mentioned problems described in the previous stage.

By the way, the internal combustion engine described in Non-Patent Document 1 is a three-cylinder engine, which suspends fuel injection and ignition combustion in one of the cylinders. When the fuel injection and ignition combustion of one cylinder are stopped in the 3-cylinder internal combustion engine, the combustion interval becomes uneven, so that the instantaneous value of the engine speed fluctuates greatly, and the internal combustion engine and the drive system of the vehicle vibrate. Will also grow.

“Ford to Offer Fuel-Saving Cylinder Deactivation Tech for 1.0 Litre EcoBoost; Global First for a 3-Cylinder Engine | Ford of Europe | Ford Media Center”, [online], [Search January 20, 2nd year], Internet <URL: https://media.ford.com/content/fordmedia/feu/en/news/2016/11/29/ford-to-offer-fuel-saving-cylinder-deactivation-tech-for-1-0 -lit.html>

The present invention suspends fuel injection and ignition combustion while maintaining an even combustion interval and without causing problems such as a decrease in the combustion chamber temperature of a specific cylinder and a decrease in the performance of a catalyst for exhaust gas purification. The purpose is to improve performance.

In order to solve the above problems, the internal combustion engine according to the present invention has the following configuration. That is, the internal combustion engine according to the present invention has an intake camshaft that makes one rotation every four rotations of the crankshaft, and two camlobes that are pivotally supported by the intake camshaft and have a symmetrical shape with the axis of the camshaft in between. The first intake cam having the first intake cam, the second intake cam shaft supported by the intake camshaft and having only one cam lobe, the exhaust camshaft that makes one rotation every four rotations of the crankshaft, and the exhaust camshaft. A first exhaust cam that is axially supported and has two camlobes that are symmetrically shaped across the axis of the camshaft, and one that is axially supported by the exhaust camshaft and has only one camrobe, or the axis of the camshaft. A second exhaust cam having two cam lobes arranged symmetrically with respect to each other and having different camlift amounts, and a first intake cam and a first exhaust cam drive the intake valve and the exhaust valve, respectively, during high load operation. It is provided with a switching mechanism for taking the first state and taking the second state in which the second intake cam and the second exhaust cam respectively open and drive the intake valve and the exhaust valve during low load operation.

Such a thing is similar to a 4-stroke internal combustion engine equipped with a camshaft that makes one rotation every two rotations of a conventional crankshaft (that is, every 720 ° CA (crank angle)) during high-load operation. During low-load operation, each cylinder performs one cycle consisting of four steps of intake stroke, compression stroke, expansion stroke, and exhaust stroke, and then during the period corresponding to the next cycle, that is, during 720 ° CA. Can be made to suspend fuel injection and ignition combustion. Therefore, it is possible to suspend fuel injection and ignition combustion while keeping the combustion interval even and without significantly lowering the combustion chamber temperature of a specific cylinder as compared with the combustion chamber temperature of another cylinder.

According to the present invention, fuel injection and ignition combustion are suspended to achieve fuel efficiency while maintaining an even combustion interval and without causing problems such as a decrease in the cylinder temperature of a specific cylinder and a decrease in the performance of a three-way catalyst. Performance can be improved.

The schematic diagram which shows the valve operating system of the internal combustion engine which concerns on one Embodiment of this invention. The schematic diagram which shows the crankshaft and intake / exhaust camshaft which concerns on the same embodiment. The schematic diagram which shows the intake valve, the rocker arm and the intake cam which concerns on the said embodiment. The perspective view which shows the intake cam and the intake cam shaft which concerns on the same embodiment. The schematic diagram which shows the intake valve, the rocker arm and the intake cam which concerns on the said embodiment. A time chart showing the state of each cylinder during high-load operation according to the same embodiment. A time chart showing the state of each cylinder during low load operation according to the same embodiment.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

As shown in FIG. 1, the intake valve 1 and the exhaust valve 2 of the internal combustion engine of the present embodiment are supported by the cylinder head 3 so as to be reciprocally slidable. The intake valve 1 and the exhaust valve 2 open and close the intake port 7 or the exhaust port 8 located between the combustion chamber 4 and the intake passage 5 or the exhaust passage 6 based on the reciprocating motion thereof.

The intake valve 1 and the exhaust valve 2 are rotationally driven via the rocker arms 11A and 11B by rotation from the intake camshaft 9 and the exhaust camshaft 10 rotatably supported by the cylinder head 3, respectively. The fulcrums 11x of the rocker arms 11A and 11B are rotatably supported by the cylinder head 3, and the points of action abut on the stem ends 1a and 2a of the intake valve 1 or the exhaust valve 2. Further, the power point portions 11f of the rocker arms 11A and 11B are pressed by the intake cams 12A and 12B or the exhaust cams 13A and 13B pivotally supported by the intake camshaft 9 or the exhaust camshaft 10.

On the other hand, both the intake camshaft 9 and the exhaust camshaft 10 are adapted to make one rotation every four rotations of the crankshaft 14. Specifically, as shown in FIG. 2, the crankshaft 14 is connected to the input end 15a of the first reduction gear 15 having a reduction ratio of 2, and the output end 15b of the first reduction gear 15 has a reduction ratio of 2. It is connected to the input end 16a of the second speed reducer 16 of the above. Since the intake camshaft 1 and the exhaust camshaft 2 are connected to the first and second output ends 16b and 16c of the second speed reducer 16, respectively, the intake camshaft 1 and the exhaust camshaft 2 are crankshafts. Makes one rotation every four rotations. The second speed reducer 16 is almost the same as this type of speed reducer used in a conventional internal combustion engine for rotating the intake camshaft and the exhaust camshaft once every two rotations of the conventional crankshaft. It has a similar configuration.

Here, the intake valve 1 and the exhaust valve 2 of each cylinder are arranged symmetrically with respect to the intermediate line between them. Hereinafter, the description will be made focusing only on the intake valve 1 side, but the exhaust valve 2 side also has the same configuration.

As shown in FIGS. 3 to 5, the intake valve 1 of each cylinder has a first cam lobe 12x that is pivotally supported by the intake camshaft 9 and has a symmetrical shape with the axis of the camshaft 9 interposed therebetween. The intake cam 12A and the second intake cam 12B, which is pivotally supported by the intake cam shaft 9 and has only one cam lobe 12x, are provided so as to correspond to each other. More specifically, each cylinder is provided with two intake valves 1, a first rocker arm 11A at a position corresponding to the middle of both intake valves 1, and a position corresponding to both intake valves 1. A second rocker arm 11B is provided respectively, so that the first rocker arm 11A is pressed by the first intake cam 12A and both second rocker arms 11B are pressed by the second intake cam 12B, respectively. It has become.

More specifically, as shown in FIGS. 3 and 4, the first intake cam 12A has both cam lobes 12x arranged at positions 180 degrees apart from each other on the base circle. The second intake cam 12B has only one cam lobe 12x, and the cam lobe 12x is arranged at a position in phase with one cam lobe 12x in the first intake cam 12A.

On the other hand, the first and second rocker arms 11A and 11B take a first state in which the first intake cam 12A opens and drives the intake valve 1 during high load operation, and the second intake cam during low load operation. A switching mechanism 17 is built in so that each of the 12Bs takes a second state in which the intake valve 1 is driven to open. As shown in FIG. 5, for example, the switching mechanism 17 has a first position (P) and a first position (P) capable of connecting the first and second rocker arms 11A and 11B and moving them synchronously. Alternatively, the connection pin 18 which is housed in the second rocker arms 11A and 11B and can move between the second position (Q) which does not connect them and the connection pin 18 are directed toward the first position (P). A hydraulic passage 19 for supplying oil for movement, a hydraulic supply source (not shown) sharing the oil pressure in the hydraulic passage 19, and a coil spring 20 for urging the connection pin 18 toward the second position (Q). Flood control to move the connection pin 18 to the first position (P) during high load operation where the accelerator operation amount exceeds the predetermined value, and to set the connection pin 18 to the second position (Q) during low load operation when the accelerator operation amount is less than the specified value. It includes a control device (not shown) that outputs a signal for controlling a valve (not shown) in the passage 19. This control device is formed by using a microcomputer system, receives a signal indicating an accelerator operation amount, and is in a high load operation when the accelerator operation amount indicated by this signal exceeds a predetermined value. A signal is output to the valve to move the connection pin 18 toward the first position (P). A signal s is output to the valve to move the pin 18 toward the second position (Q). In FIG. 5, a part of the rocker arms 11A and 11B is broken to show the existence of the connection pin 18 of the switching mechanism 17.

Here, during high-load operation, since the connection pin 18 is arranged at the first position (P) as described above, either of the two cam lobes of the first intake cam 12A presses the first rocker arm 11A. Even in this case, the second rocker arm 11B operates integrally with the first rocker arm 11A to drive the intake valve 1. In other words, the first intake cam 12A drives the intake valve 1. Therefore, the intake valve 1 opens twice while the crank arm 14 rotates four times (every 1440 ° CA).

On the other hand, during low load operation, since the connection pin 18 is arranged at the second position (Q) as described above, the first rocker arm 11A does not interlock with the second rocker arm 11B, and the intake valve 1 Is driven from the second intake cam 12B via the second rocker arm 11B. In other words, the second intake cam 12B drives the intake valve 1. Therefore, the intake valve 1 opens once while the crank arm 14 rotates four times (every 1440 ° CA).

The exhaust valve 2 and the exhaust cams 13A and 13B are also connected via the first and second rocker arms 11A and 11B in the same manner as the intake valve 1 and the intake cams 12A and 12B described above, and are raised by the switching mechanism 17. The first exhaust cam 13A opens and drives the exhaust valve 2 during load operation, and the second exhaust cam 13B opens and drives the intake valve 2 during low load operation. It is designed to be taken. The first and second exhaust cams 13A and 13B have the same shape as the first and second intake cams 12A and 12B, respectively. In other words, in the first exhaust cam 13A, both cam lobes 13x are arranged at positions 180 degrees apart from each other on the base circle. The second exhaust cam 13B has only one cam lobe 13x, and the cam lobe 13x is arranged at a position in phase with one cam lobe 13x in the first exhaust cam 13A. Since the first and second rocker arms 11A and 11B and the switching mechanism 17 have the same configuration as those arranged between the intake valve 1 and the intake cams 12A and 12B, the corresponding parts have the same reference numerals. Is added to omit the description.

Therefore, during high load operation, the first intake cam 12A and the first exhaust cam 13A take the first state of opening and driving the intake valve 1 and the exhaust valve 2, respectively, and during low load operation, the second intake cam 12B The second exhaust cam 13B takes a second state in which the intake valve 1 and the exhaust valve 2 are opened and driven, respectively.

From the above, the operation mode during high-load operation is as shown in FIG. 6 for the time chart, and the operation mode during low-load operation is as shown in FIG. 7 for the time chart.

That is, according to the present embodiment, the intake camshaft 9 and the exhaust camshaft 10 make one rotation every four rotations of the crankshaft 14, and then a second intake having only one cam lobe during low load operation. Since the intake valve 1 and the exhaust valve 2 are driven to open in the second state by the cam 12B or the second exhaust cam 13B, each cylinder is as shown in the time chart of FIG. 7 described above. After performing one cycle consisting of four steps of intake stroke, compression stroke, expansion stroke and exhaust stroke, fuel injection and ignition combustion can be suspended during 720 ° CA corresponding to the next cycle. Therefore, the fuel efficiency can be improved by suspending fuel injection and ignition combustion while maintaining the combustion interval of each cylinder evenly and without significantly lowering the combustion chamber temperature of the cylinders.

On the other hand, during high-load operation, the intake valve is provided by the first intake cam 12A and the first exhaust cam 13A having two cam lobes 12x having a symmetrical shape with the axis of the intake cam shaft 9 or the exhaust cam shaft 10 interposed therebetween. Since 1 and the exhaust valve 2 are set to take the first state in which the valve is opened, as shown in the time chart of FIG. 6 described above, the intake camshaft and the exhaust valve are exhausted every two rotations of the normal crankshaft. It can be operated in the same manner as a 4-stroke internal combustion engine in which the camshaft makes one rotation.

In other words, while keeping the combustion interval of each cylinder even and suppressing the vibration of the vehicle etc., the increase in mechanical loss due to the decrease in the combustion chamber temperature of the cylinder, the increase in the fuel injection amount when the cylinder operation is restarted, and the third Improving fuel efficiency by suspending fuel injection and ignition combustion during low-load operation while performing the same operation as a conventional internal combustion engine during high-load operation without causing problems such as deterioration of the performance of the original catalyst. It is possible to realize an internal combustion engine that can be planned.

Moreover, since the rotation speeds of the intake camshaft 9 and the exhaust camshaft 10 are half that of a general internal combustion engine, it is possible to reduce friction loss and wear of the bearing portions of the camshafts 9 and 10.

Then, when the fuel injection and ignition combustion of one cylinder are stopped, the pumping loss can be significantly reduced by stopping the on-off valves of the intake valve 1 and the exhaust valve 2 corresponding to the cylinder, so that further fuel efficiency performance can be further achieved. Can also be improved.

The present invention is not limited to the embodiments described above.

For example, in the above-described embodiment, the second intake cam has only one cam lobe, but a second intake cam having two cam lobes symmetrically arranged with respect to the axial center of the intake cam shaft and having different cam lift amounts is adopted. You may. In other words, every 720 ° CA, the intake valve is driven by a cam lobe having a normal cam lift amount to inject fuel and ignite, and the intake valve is driven by a cam lobe having a cam lift amount smaller than the normal cam lift amount. The fuel injection and the hibernation state in which the ignition combustion is suspended may be alternately taken. In this case, since the intake valve opens slightly even in the hibernation state, there is a problem that the engine oil is drawn into the combustion chamber side, unlike the mode in which the piston is lowered toward the bottom dead center while the intake valve is closed. It is hard to occur.

Further, the present invention can be applied to other than the 3-cylinder internal combustion engine. In particular, it is possible to effectively obtain the above-mentioned effect of the present invention in an internal combustion engine in which an odd number of cylinders are arranged in series, or in an internal combustion engine in which the number of cylinders such as in-line 6 cylinders, V type 6 cylinders, and V type 12 cylinders is a multiple of 3. can.

Further, in order to rotate the intake camshaft once every four rotations of the crankshaft, instead of using two reduction gears having a reduction ratio of 2 as in the above-described embodiment, one reduction gear having a reduction ratio of 4 is used. You may use only one.

In addition, in the above-described embodiment, the accelerator operation amount is used as a parameter used for determining whether the vehicle is in high load operation or low load operation, but the accelerator operation speed and throttle valve are not limited to the accelerator operation amount. Any amount indicating the output (required load) of the internal combustion engine required by the driver, such as the opening degree, the amount of fresh air intake air, and the intake pipe pressure, may be used.

Then, the present invention may be applied to an internal combustion engine in which a rocker arm is not interposed between the intake / exhaust cam and the intake / exhaust cam shaft, and the first intake cam and the first exhaust cam are each intake valves during high load operation. And the exhaust valve is opened and driven in the first state, and the second intake cam and the second exhaust cam are in the second state in which the intake valve and the exhaust valve are opened and driven, respectively, during low load operation. The switching mechanism for this purpose is not limited to that of the above-described embodiment, and any one may be adopted. Further, the present invention may be applied not only to a spark-ignition internal combustion engine but also to a compression ignition internal combustion engine such as a diesel engine.

In addition, various modifications may be made as long as the gist of the present invention is not impaired.

9 ... Intake camshaft 10 ... Exhaust camshaft 12A ... First intake cam 12B ... Second intake cam 12x ... Cam lobe 13A ... First exhaust cam 13B ... Second exhaust cam 14 ... Crankshaft 17 ... Switching mechanism

Claims (1)

An intake camshaft that rotates once every four rotations of the crankshaft,
A first intake cam that is pivotally supported by the intake camshaft and has two cam lobes symmetrical with respect to the axial center of the intake camshaft.
A second intake cam that is pivotally supported by the intake camshaft and has only one cam lobe, or has two cam lobes that are symmetrically arranged across the axis of the intake cam shaft and have different cam lift amounts.
An exhaust camshaft that makes one revolution every four crankshaft revolutions,
A first exhaust cam that is pivotally supported by the exhaust camshaft and has two cam lobes that are symmetrically shaped across the axis of the exhaust camshaft.
A second exhaust cam that is pivotally supported by the exhaust camshaft and has only one cam lobe,
During high load operation, the first intake cam and first exhaust cam take the first state of opening and driving the intake valve and exhaust valve, respectively, and during low load operation, the second intake cam and the second exhaust cam are respectively. An internal combustion engine including a switching mechanism for taking a second state of driving the intake valve and the exhaust valve by opening the valve.

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