JPH0229209Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a lubricating device for a valve train of an internal combustion engine, and particularly relates to the structure of a lubricating oil passage that supplies lubricating oil to the valve train. [Prior Art] A valve train of an internal combustion engine includes several sliding parts such as a cam face part and a cam journal part. The friction loss of these sliding parts of the valve train accounts for a large amount of the friction loss of the entire engine. Therefore, in order to improve engine output and fuel efficiency, friction loss in the valve train must be kept low.
For this purpose, good lubrication conditions are required. Conventional lubrication of valve train systems, like other parts, requires:
Lubricating oil with a relatively high temperature of 80°C to 90°C has been supplied. However, large loads tend to be applied to the sliding parts of valve train systems, and high-temperature lubricating oil tends to have low viscosity, resulting in boundary lubrication. Therefore, in order to avoid a boundary lubrication state and reduce friction loss, it is advantageous for the viscosity of the lubricating oil to be large. In order to increase the viscosity of lubricating oil, it is sufficient to lower the temperature of the lubricating oil, and to deal with this, structures have been proposed that supply cooled lubricating oil to the valve train (for example, , JP-A-58-135312, JP-A-57-92812, JP-A-57-
162910, Utility Model Application Publication No. 1983-6908). [Problem to be solved by the invention] By the way, in the cam face part of the valve train, where the load is heavy, the higher the viscosity of the lubricating oil, the more boundary lubrication can be avoided, which is advantageous in reducing friction loss. Since the journal section becomes fluid-lubricated in the high rotation range, it has been shown that lowering the viscosity of the lubricating oil will reduce friction loss (for example, American Society of Automotive Engineers Report No. 830165). . Therefore, by changing the viscosity of the lubricating oil supplied to each part depending on the operating state of the engine, it is possible to promote reduction in friction loss. In addition, in conventional lubricating devices, lubricating oil was supplied to the cam face part by discharging the lubricating oil supplied into the camshaft from a small hole opened on the outer circumferential surface of the camshaft. When changing the temperature of the lubricating oil supplied to the cam face part, the method of supplying the lubricating oil to the cam face part becomes an issue. That is, a new problem arises in that lubricating oil must be properly supplied to the cam face portion without going through the passage within the camshaft. Focusing on the above problem, this invention controls the viscosity of the lubricating oil supplied to each part of the valve train according to the operating state of the engine, and reduces the friction loss of the valve train most efficiently in all operating ranges. It is an object of the present invention to provide a lubricating device that can improve the output and fuel efficiency of an engine and can supply lubricating oil to a cam face portion in a satisfactory manner. [Means for Solving the Problems] A lubrication device for a valve train according to the present invention in accordance with this objective is to connect an oil passage that supplies lubricating oil to a valve train of an internal combustion engine with lubricating oil to a cam face part of the valve train. The oil passage is branched into a cam face system passage that supplies lubricating oil to areas other than the cam face part of the valve train, and a cooling device that cools the lubricating oil is provided in the oil passage, and the cooling device is provided. A first control valve is provided in the cam face system passage that communicates with the bypass passage when the engine is warmed up and communicates with the oil passage that has passed through the cooling device after the engine has warmed up. , a second control valve is provided in the journal passageway, which communicates with the bypass passage when the engine is warmed up and at high speeds, and communicates with the oil passage that has passed through the cooling device at times other than when the engine is warmed up and when the engine speeds are high. established,
The cam face system passage is provided with a jet that injects lubricating oil as an oil jet toward the cam face portion. [Function] In such a valve train lubrication system, there is no need to particularly cool the lubricating oil during warm-up, so low-temperature, high-viscosity lubricating oil that does not pass through the cooling device is supplied to the cam face and journal system. be done. After warming up, low-temperature, high-viscosity lubricating oil that has passed through the cooling device is constantly supplied to the cam face part, where it is advantageous to have a higher viscosity lubricating oil in all rotational speed ranges, by switching control of the first control valve. Boundary lubrication at the cam face is avoided. On the other hand, lubricating oil is supplied to the journal system through a cooling device in the low rotation range, but fluid lubrication becomes dominant in the high rotation range, so lubricating oil is supplied from the uncooled bypass passage. The second control valve is controlled to reduce friction loss in the journal system in the high rotation range. Therefore, while a boundary lubrication condition at the cam face is avoided, a good lubrication condition is ensured in other parts, and friction loss in the valve train is efficiently reduced depending on the operating condition. Ru. In addition, since the cam face system passage is equipped with a jet that injects lubricating oil as an oil jet toward the cam face part, the lubricating oil can be sufficiently attached to the lubricated surface, and a sufficient lubrication state on the lubricated surface is ensured. Ru. Furthermore, since the lubricating oil injected from the jet is always cooled and has a high viscosity, it does not become mist even when injected, and an increase in oil mist within the cylinder head is also suppressed. [Embodiments] Preferred embodiments of the valve train lubrication device of the present invention will be described below with reference to the drawings. FIG. 1 shows a system of lubricating oil passages in a lubricating device for a valve train according to an embodiment of the present invention. The lubricating oil path shown in FIG. 1 is, for example, among the lubricating oil paths of a conventional general internal combustion engine shown in FIG. Valve train oil passage 4 after branching from the lubricating oil passage
(for example, part A in the figure). The oil passage 4 is branched into a cam face system passage 6 that supplies lubricating oil to the cam face part 5, and a journal system passage 8 that supplies lubricating oil to other journal parts 7, etc., and the lubricating oil is supplied to each branch. It is supplied to the valve train through passages 6 and 8. The means for supplying lubricating oil from the cam face system passage 6 to the cam face part 5 is a conventional lubricating oil supply mechanism shown in FIG.
Instead of supplying through the system, for example, as shown in FIG. 4, a pipe 13 with a jet 12 is provided, and the supply system is configured as a separate supply system from the journal system. That is, in the example shown in FIG. 4, the oil passage 10 in the camshaft 9 is used for a journal part, etc.
No small hole is provided for the cam face. Then, from the jet 12 of the pipe 13, the cam 14,
Lubricating oil 30 from the cam face system passage 6 is supplied to the cam face portion 5 of the rocker arm 15 and the like as an oil jet. Returning to FIG. 1 again, the oil passage 4 is provided with a cooling device 16, and this cooling device 16
Bypass passage 1 that bypasses the part provided with
7 is provided. In this embodiment, the cooling device 1
6 is provided at a portion before the cam face system passage 6 and the journal system passage 8 diverge. This cooling device 16 is constituted by a double tube type cooler, which is already mass-produced, as shown in FIG. 5, for example, and it is preferable to use fuel as the refrigerant 18.
However, the cooler may be of any type, such as an air-cooled radiator type. The bypass passage 17 is branched into two parts, and then connected to the cam face passage 6 and the journal passage 8, respectively. A first control valve 19 and a second control valve 20 are provided at the junctions of the bypass passages 17 with the cam face passages 6 and the journal passages 8, respectively. As will be described later, each control valve 19, 20 supplies lubricating oil to the valve train system, that is, the cam face system passage 6 and the journal system passage 8, depending on the operating state of the engine (warm-up state and engine rotation speed). The lubricating oil that has passed through the cooling device 16 is switched to the lubricating oil from the bypass passage 17 that does not pass through the cooling device 16. In other words, the first control valve 19 provided in the cam face system passage 6 has a function of communicating with the bypass passage 17 when the engine is warmed up, and communicating with the oil passage 4 that has passed through the cooling device 16 after the engine is warmed up. are doing. The second control valve 20 provided in the journal system passage 8 communicates with the bypass passage 17 when the engine is warmed up and at high speeds, and the oil passage 4 that has passed through the cooling device 16 communicates with the bypass passage 17 when the engine is warmed up and at high speeds. It has the function of communicating with This first control valve 19 and second control valve 20
is connected to the microcomputer 21 in this embodiment, and is operated based on a command signal from the microcomputer 21. The microcomputer 21 includes at least an engine speed signal 22 from an engine speed detection sensor (not shown);
An oil temperature signal 23 from a lubricating oil temperature detection sensor (not shown), for example, an oil temperature signal from a sensor provided in the cam face system, is input. Each control valve 1 is installed in the microcomputer 21 in advance.
A map for controlling 9 and 20 is stored. The contents of the map are shown in Table-1. In other words, whether the microcomputer 21 is warming up or has finished warming up (for example, the oil temperature is 40°C).
is used as a guideline for determination), the engine speed is further determined, and based on the commands from the microcomputer 21 based on these determinations, the first control valve 1 is
9 and the second control valve 20 are operated as shown in Table-1.

[Table] In Table 1, control valve off means
In the figure, the white marks of each control valve 19, 20 are open, and "off" of the control valve means that the black marks are open. That is, when the first control valve 19 and the second control valve 20 are in the OFF state, the uncooled lubricating oil from the bypass passage 17 is supplied to the cam face system passage 6 and the journal system passage 8, and each control valve 19, 20 In the on state, lubricating oil that has passed through the cooling device 16 is supplied to the cam face system passage 6 and the journal system passage 8. Note that the timings of the opening and closing operations of the control valves 19 and 20 are slightly shifted in this embodiment due to the convenience of the electric circuit. In other words, since the first control valve 19 and the second control valve 20 are independently controlled by the computer 21, it is possible to operate them at different timings by changing the program. The current flowing through the control circuit can be suppressed more than when the two control valves 19 and 20 are operated at the same time. In addition, each control valve 1
Even if 9 and 20 are activated at the same timing,
Furthermore, even if the operation is performed with a slight time difference, the lubrication performance will not be significantly affected. Next, the operation of the above-mentioned valve train lubrication device will be explained. During cold and warm-up periods, the lubricating oil is in a low temperature state without having to pass through the cooling device 16.
In response to a command from the computer 21, the first control valve 19 and the second control valve 20 are turned off, and lubricating oil with low temperature and high viscosity is supplied from the bypass passage 17 to the cam face system passage 6 and the journal system passage 8. . After warming up, the temperature of the lubricating oil supplied from the oil pump has risen considerably, but in the cam face section 5, it is advantageous to have a higher viscosity over the entire rotational speed range. The first control valve 19 is turned on, and the cam face system passage 6 is always supplied with low temperature, high viscosity lubricating oil that has passed through the cooling device 16. This high viscosity lubricating oil is
The lubricating oil is injected as an oil jet from 2 toward the cam face portion 5, and the lubricating oil is sufficiently deposited on the lubricating surface. As a result, a boundary lubrication state can be avoided even in the cam face portion 5 where the load on the sliding portion is large. In addition, the lubricating oil injected from the jet 12 is
Since the oil is constantly cooled and has a high viscosity, it does not become mist even when injected, and the increase in oil mist within the cylinder head is also suppressed. On the other hand, for the journal system, the second control valve 20 is turned on in the low to medium rotation speed range, and low-temperature, high-viscosity lubricating oil is supplied through the cooling device 16. Therefore, the boundary lubrication condition is avoided in the same way as described above. Then, when the engine reaches a high rotational speed range, fluid lubrication becomes dominant in the journal section 7, so the second control valve 20 is turned off and relatively high temperature and low viscosity lubricating oil is supplied from the bypass passage 17. Ru. In this way, since low-viscosity lubricating oil is supplied while fluid lubrication is ensured, friction loss in the journal portion 7 is reduced. Note that the standard for this switching rotation speed varies depending on the engine, but for example, if the maximum rotation speed is 6000 rpm, it is preferably about 4000 rpm. Furthermore, when the cooling device 16 shown in FIG. 5 is used and fuel is used as the refrigerant 18, the fuel is heated by heat exchange with oil, so the fine particles of the injected fuel are smaller than before. This has the secondary effect of promoting combustion and further improving the combustion state. [Effect of the invention] Therefore, according to the invention, the first control valve and the second control valve are switched during warm-up, after warm-up, and according to the engine speed, and the cam face of the valve train is changed. This enables lubricating oil of the most appropriate viscosity to be supplied to the valve system and journal system, thereby preventing the cam face from entering a boundary lubrication state and reducing friction in the valve train most efficiently in all operating ranges. The effect is that losses can be reduced, engine output can be improved, and fuel efficiency can be improved. In addition, the cam face system passage is provided with a jet that injects lubricating oil as an oil jet toward the cam face part, so that the lubricating oil can be sufficiently attached to the lubricated surface of the cam face part, and the lubrication state in the cam face part can be maintained. Can be maintained well. Furthermore, since the lubricating oil injected from the jet is always cooled and has a high viscosity, the increase in oil mist in the cylinder head is suppressed, and the intake system It is possible to suppress the amount of oil mist sucked into.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a lubricating oil passage of a valve train lubrication device according to an embodiment of the present invention, and Fig. 2 is a conventional general lubricating oil passage showing the position where the device of Fig. 1 is applied. Fig. 3 is an enlarged longitudinal sectional view of the cam face part showing an example of a conventional lubricant supply mechanism to the cam face part, and Fig. 4 is an enlarged longitudinal sectional view of the cam face part according to an embodiment of the present invention. FIG. 5 is an enlarged schematic configuration diagram showing an example of a cooling device. 4...Oil passage, 5...Cam face section, 6
...cam face system passage, 7...journal part,
8... Journal system passage, 9... Camshaft,
10...Oil passage, 12...Jet, 13...
...Pipe, 14...Cam, 15...Rotsuka arm, 16...Cooling device, 17...Bypass passage,
18... Refrigerant, 19... First control valve, 20...
second control valve, 21... microcomputer,
22...Engine speed signal, 23...Oil temperature signal.

Claims (1)

[Scope of utility model registration request] The oil passage that supplies lubricating oil to the valve train of an internal combustion engine is divided into a cam face system passage that supplies lubricating oil to the cam face part of the valve train system, and a journal system passage that supplies lubricant oil to areas other than the cam face part of the valve train system. A cooling device for cooling the lubricating oil is provided in the oil passage, and a bypass passage is provided to bypass the portion where the cooling device is provided, and the cam face system passage communicates with the bypass passage when the engine is warmed up. After the engine is warmed up, a first control valve is provided that communicates with the oil passage that has passed through the cooling device, and the journal system passage communicates with the bypass passage when the engine is warmed up and at high speeds. A second control valve is provided that communicates with the oil passage passing through the cooling device except during times of operation and high rotation,
A lubricating device for a valve train, characterized in that the cam face system passage is provided with a jet for injecting lubricating oil as an oil jet toward the cam face portion.