JPS63965Y2 - - Google Patents

Description

[Detailed description of the invention] The invention is a double overhead camshaft engine (hereinafter referred to as
It's called a DOHC engine. ) relates to the structure of the cylinder head.

The blow-by gas that leaks from the combustion chamber in the upper part of the piston to the lower part of the piston through the gap between the piston circumferential surface and the cylinder bore contains many unburned components. Blow-by gas reduction devices are widely used that prevent gas from being released into the atmosphere by recirculating the gas to the intake side of the gas. Conventionally, in blowby gas return systems for DOHC engines that have two separate cam chambers, a blowby gas upward passage that rises from the crank chamber through the cylinder block and cylinder head is opened in the cam chamber. A blow-by gas outlet is formed in the cam chamber, and the blow-by gas flowing into the cam chamber is taken out from the blow-by gas outlet and recirculated into the intake system of the engine.

In such a conventional blowby gas return system, the blowby gas up passage and the blowby gas outlet are opened in the same cam chamber, so the blowby gas mixed with oil mist in the crankcase is sufficiently separated from the oil mist. It may flow into the engine's intake system without being removed, leading to problems such as increased oil consumption and decreased exhaust gas purification performance.

In order to eliminate this problem, the applicant first communicated the two cam chambers with each other through a communication passage, connected the blow-by gas upward passage to one cam chamber, and connected the blow-by gas upward passage to the other cam chamber. A blow-by gas reduction device provided with a gas outlet has been proposed. By adopting this configuration, the distance of the space through which the blow-by gas flows becomes longer, and while flowing through the space, the oil mist combines with each other to form a large oil mist, which falls to the bottom of the space and sinks into the flowing oil. As a result, the oil mist in the blow-by gas is further separated.

However, in the above-mentioned apparatus, although the oil mist separation effect is improved, the following problems still remain. That is, the blow-by gas communication passage that communicates the two cam chambers is also a passage for oil flowing between the two cam chambers. Since a cam gear for driving the distributor is located near one of the communication passages, the cam gear causes the oil flowing through the communication passage to flow back into the cam chamber on the blow-by gas outlet side. If this oil backflow is severe, there is a risk that oil will blow out from the blow-by gas outlet into the intake system.

The present invention has a structure of a cylinder head that has two cam chambers and communicates the two cam chambers with a communication passage for blow-by gas and oil circulation, in which oil backflows by a cam gear for driving a distributor in the communication passage. The purpose is to prevent oil from blowing out into the intake system.

To achieve this objective, the structure of the cylinder head of the present invention has the following configuration. That is, two separate cam chambers that house the respective camshafts of a DOHC engine are communicated with each other through a communication passage, and one cam chamber is opened with a blow-by gas upward passage rising from the crank chamber and an oil return passage. A blow-by gas outlet equipped with a full plate is provided in the other cam chamber. Of the communication passages, a weir that provides resistance to the backflow of oil is provided in the communication passage facing the cam gear for driving the distributor.

By adopting such a configuration, in the structure of the cylinder head of the present invention, oil is pumped through the communicating path by the cam gear for driving the distributor, and from the cam chamber provided with the oil return path to the blow-by gas outlet. Since the dam prevents the oil from flowing back into the cam chamber provided with the oil, the oil is prevented from blowing out into the intake system due to the oil backflow caused by the drive cam gear of the distributor. Therefore, an increase in oil consumption is not caused.

Hereinafter, preferred embodiments of the structure of the cylinder head of the present invention will be described with reference to the drawings.

In FIGS. 1 to 4 showing an embodiment of the present invention, a cylinder head 2 is fixed to a cylinder block 1 of a DOHC engine.
A cylinder head cover 3 is fixed to the cylinder head with bolts 4. Two cam chambers 5 and 6 are formed between the cylinder head 2 and the cylinder head cover 3 and extend in the longitudinal direction of the engine. Camshafts 7, 8 are arranged in the two cam chambers 5, 6, respectively, and the camshafts 7, 8 are rotatably attached to the cylinder head 2 by camshaft bearing caps 9, 10.

A blow-by gas upward passage 11 is formed through the cylinder block 1 and the cylinder head 2. A blow-by gas upward passage 11 rises from the crank chamber 12 of the cylinder block 1 to one of the two cam chambers 5, 6, the cam chamber 5. The blow-by gas upward passage 11 opens at one location in the center of the cam chamber 5 in the longitudinal direction.
The cam chamber 5 is also provided with an oil return passage 34. No oil return passage is provided on the cam chamber 6 side. The cam chamber 5 communicates with the other cam chamber 6 through a horizontally extending communication passage 13 formed in the cylinder head 2. The communication passages 13 are provided at a total of three locations, one at the center in the longitudinal direction of the cam chambers 5 and 6, and one at both ends. A blow-by gas outlet 14 is provided at the upper end of the other cam chamber 6. Inside the cam chamber 6, an oil draining baffle plate 15 is provided near the blow-by gas outlet 14.

A passage for returning oil to the oil pan is provided in the cam chamber 5 on the side of the cam chambers 5 and 6 where the blow-by gas upward passage 11 is provided. Therefore, the communication passage 13 constitutes a flow passage for blow-by gas flowing from the cam chamber 5 to the cam chamber 6, and also constitutes a flow passage for oil flowing from the cam chamber 6 to the cam chamber 5.

A cam gear 7a for driving the distributor 32 is located within the cam chamber 5 in which the oil return passage 34 is provided, and at a position corresponding to the communication passage 13 at the front end of the engine, which is closest to the communication passage 13. This driving cam gear 7a is the camshaft 7
The distributor gear 32b is formed at the distal end of the rod 32a of the distributor 32 and extends to the position of the drive cam gear 7a. This driving cam gear 7
The rotational direction a is such that the teeth of the gear 7a cause the oil flowing in the lower part of the cam chamber 5 to flow back into the cam chamber 6 through the communication passage 13 at the front end of the engine, as shown by arrow A in FIG. This data streamer 3
A weir 35 made of a plate extending in a direction perpendicular to the longitudinal direction of the communication path 13 is provided in the communication path 13 facing the second drive cam gear 7a at the middle of the communication path 13 and at the bottom of the communication path 13. . The upper part of the weir 35 in the communication passage 13 is open, and the communication passage 13 is not blocked by the weir 35. 36 is a plug, and the plug insertion port also functions as an opening for installing the weir 35. The weir 35 is connected to the other two communication passages 13
is not provided.

The blow-by gas outlet 14 is connected to the intake system. For example, it is connected to the surge tank 18 via a blow-by gas recirculation passage 16 and an opening 17, and is also connected to the upstream side of the valve 21 of the throttle body 20 via a blow-by gas recirculation passage 19. 22 indicates an air cleaner unit attached to the throttle body 20. The surge tank 18 is connected to an intake passage 2 formed in the cylinder head 2 via an intake manifold 23.
4, and the intake passage 24 opens into a combustion chamber 25.

In the figure, 26 indicates an exhaust passage formed in the cylinder head 2, 27 indicates an intake valve, and 28 indicates an exhaust valve. Also, 29 is Biston, 30
is the connecting rod, 31 is the crankshaft, 3
2 is a distributor, and 33 is a spark plug.

Next, the operation of the apparatus of the above embodiment will be explained.

When the viston 29 moves up and down, the blow-by gas that flows into the crank chamber 12 from the combustion chamber 25 mixes with the oil mist in the crank chamber 12 and flows into the blow-by gas upward passage 11 . This blow-by gas rises along the blow-by gas upward passage 11 together with the oil mist, and flows into one of the cam chambers 5. The blow-by gas that has flowed into the cam chamber 5 is diffused along the longitudinal direction of the camshaft 7.

The blow-by gas filling the cam chamber 5 flows into the other cam chamber 6 through the communication path 13. This structure of the communication passage 13 increases the distance from the blow-by gas inlet to the cam chamber 5 to the blow-by gas outlet of the cam chamber 6. Therefore, while the blow-by gas is flowing, the oil mist in the blow-by gas combines with other oil mist to form a large oil mist and enters the oil liquid level below, or it hits the wall and the mist particles are removed. . In this way, oil mist is removed from the blow-by gas. Since the oil mist particles that have not yet been separated are caught by the buffer plate 15 disposed near the blow-by gas outlet 14, the blow-by gas from which the oil mist has been sufficiently separated is sucked out from the blow-by gas outlet 14. .

In the communication path 13, oil flows from the cam chamber 6 toward the cam chamber 5. In other words, the cam chamber 6 is ejected to lubricate the cam part and the cam journal.
The oil that has fallen to the lower part of the cam chamber 5 flows from the cam chamber 6 to the cam chamber 5 through the communication passage 13, and returns to the oil pan through the oil return passage 34 opened to the cam chamber 5.
Further, the blow-by gas flows from the cam chamber 5 to the cam chamber 6. That is, the flow directions of blow-by gas and oil are opposite.

By the way, among the communication passages 13, the communication passage 13 facing the driving cam gear 7a of the distributor 32
The oil flowing through the drive cam gear 7a tends to flow back from the cam chamber 5 to the cam chamber 6, but since the communication passage 13 is provided with a weir 35, the back flow is suppressed. In this case, when the oil level is lower than the height of the weir 35, oil backflow is completely prevented, but when the oil level is higher than the height of the weir 35, some backflow may occur, but the drive gear Since the oil backflow force caused by 35 acts on a relatively low portion of the communication path 13, backflow is substantially prevented. In addition, since the upper part of the communication path 13 is not blocked, the blow-by gas flows smoothly, and
If the oil level rises for some reason,
Oil will flow from the cam chamber 6 to the cam chamber 5 through the space above the weir. In this way, backflow is prevented, so the risk that the oil level in the cam chamber 6 abnormally rises due to the backflow of oil by the driving cam gear 7a and the oil blows out into the intake system is eliminated. .

Part of the blowby gas after oil mist separation sucked out from the blowby gas outlet 14 flows into the surge tank 18 through the blowby gas recirculation passage 16 and opening 17, and part of the blowby gas after oil mist separation flows into the surge tank 18. The gas flows into the upstream side of the valve 21 of the throttle body 20 through the blow-by gas recirculation passage 19. This blow-by gas then flows into the combustion chamber 25 again through the intake manifold 23 and the intake passage 24, where it is combusted.

As explained above, according to the structure of the cylinder head of the present invention, a dam is provided in the communication passage that communicates the two cam chambers, and which faces the drive cam gear of the daylight viewer. It is possible to prevent the backflow of oil due to the cam gear, and it is possible to completely prevent the oil from blowing out into the intake system and the accompanying increase in oil consumption.

Furthermore, since the weir prevents oil backflow, there is an advantage that the smooth flow of blow-by gas is not obstructed.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a blow-by gas reduction system equipped with the structure of the cylinder head of the present invention;
Figure 3 is a schematic plan view of the engine according to the present invention, Figure 3 is a sectional view taken along the - line in Figure 2, Figure 4 is a longitudinal sectional view of the communication path in the weir area, and Figure 5 is a longitudinal sectional view of the communication path in the weir area.
The figure is a sectional view of the structure of the cylinder head of the present invention, and FIG. 6 is a partial plan view of the cylinder head of FIG. 5. 2... Cylinder head, 5, 6... Cam chamber,
7, 8...Camshaft, 7a...Driving cam gear, 11...Blow-by gas upward passage, 13...
Communication path, 14...Blow-by gas outlet, 15...
...Batsuful Plate, 32... Day streamer.

Claims (1)

[Scope of utility model registration request] In a double overhead camshaft engine having two cam chambers, the two cam chambers are communicated with each other through a communication passage, and one of the two cam chambers is provided with a blow-by gas up passage and an oil return passage. At the same time, a blow-by gas outlet equipped with a buttful plate is provided in the other cam chamber, and a cam gear for driving the distributor is located at a position corresponding to one of the communication passages in the one cam chamber. A structure of a cylinder head characterized in that a weir is provided at a lower part of the one communication passage facing the driving cam gear.