JPS6224732Y2 - - Google Patents

Description

[Detailed description of the invention] The invention relates to a two-stroke engine equipped with a carburetor with a fuel pump, and includes a crank chamber oil drain passage and a crank chamber pressure (positive and negative pulsating pressure) for operating the carburetor fuel pump. This invention relates to a crank chamber drain oil/internal pressure extraction passage switching device for a two-stroke engine which is improved so as to selectively switch between an internal pressure extraction passage and an internal pressure extraction passage.

Conventionally, in a two-stroke engine equipped with a fuel pump carburetor that operates the fuel pump diaphragm by alternating positive and negative pressure (pulsating pressure) in the crank chamber and introduces fuel through the fuel pump valve, the first As shown in the figure, an oil drain pot 2 is attached to the lower side of the crankcase 1 so as to communicate with the crank chamber, and a crank chamber pressure outlet 3 is attached to the crankcase 1 at a different position from where the oil drain pot 2 is attached. is provided, and the extraction portion 3 is connected to the conduit 4.
It communicates with the crankcase internal pressure introduction part 6 of the fuel pump-equipped carburetor 5 through. In addition, the oil drain pot 2 has a valve body 8 in the oil drain passage 7 that communicates the crank chamber with the outside, as shown in FIGS. 2A, B, and C.
is installed, and by the rotation of this valve body 8, the oil drain passage 7 is opened.
It is designed to open and close. Incidentally, in FIG. 1, reference numeral 9 indicates an air cleaner.

In a conventional two-stroke engine equipped with a carburetor with a fuel pump, the crank chamber oil drain hole and the internal pressure outlet for extracting the crank chamber pressure for fuel pump operation are separately provided. Later on, the engine may be operated without closing the oil drain valve, and in this case, the carburetor fuel pump may malfunction, and
There is an inconvenience that part of the raw gas leaks from the oil drain hole of the crankcase. In addition, in the conventional two-stroke engine, the crank chamber and the fuel pump of the carburetor are in communication even when the crank chamber oil drain hole is open and the fuel pump of the carburetor is in communication. is supplied to the fuel pump, which operates and supplies fresh fuel.

By the way, in a two-stroke engine equipped with a carburetor with a fuel pump, while preventing forgetting to close the crank chamber oil drain hole, it is also possible to prevent crank chamber pressure from being supplied to the fuel pump during oil draining.
There are no countermeasures to prevent malfunction of the carburetor fuel pump, to prevent the leakage of raw gas, or to cut off the supply of crank chamber pressure to the fuel pump during exhaust oil, and it is simply a practical technique developed in the 1970s. No. 18839 merely discloses a raw gas removal device for a two-stroke engine.

The present invention was developed in view of these circumstances, and prevents forgetting to close the crank chamber oil drain hole, thereby eliminating malfunction of the carburetor fuel pump and leakage of raw gas from the oil drain hole. A two-stroke engine crank which automatically shuts off the communication between the crank chamber and the carburetor fuel pump when draining oil from the crank chamber, thereby preventing the supply of fuel due to the operation of the fuel pump at the time of draining oil. It is an object of the present invention to provide a chamber drainage oil-internal pressure extraction passage switching device.

In order to achieve the above object, the present invention provides a crank chamber exhaust oil/internal pressure outlet passage switching device for a two-stroke engine, which is a carburetor with a fuel pump that is operated by the alternating action of positive and negative pressures in the crank chamber, and into which fuel is introduced. In a two-stroke engine equipped with a 2-stroke engine, a switching socket is installed on the lower side of the crankcase, a common passageway for drain oil and internal pressure is provided in the switching socket that communicates with the crank chamber, and this common passage is used as a drain oil passage and an internal pressure take-out passage. A valve body is disposed at the branched portion to selectively switch to either the oil drain passage or the internal pressure extraction passage, while the internal pressure extraction passage of the switching outlet is communicated with the carburetor fuel pump via a conduit. It is characterized by what it did.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 3 to 6, in which FIG. 3 is a front view showing a two-stroke engine, FIGS. 4A and B are front and side views showing a switching cock, Figures 5A and B are a sectional view and a plan view of the switching cock switched to the oil drain side, and Figure 6
Figures A and B are a sectional view and a plan view of the switching cock switched to the internal pressure extraction side.

In these figures, reference numeral 11 is the two-stroke engine body, 12 is the cylinder, 13 is the crankcase, 14 is the air cleaner, and 15 is the carburetor. ) actuates a fuel pump diaphragm and introduces fuel through a fuel pump valve. A switching knob 17 having a threaded portion 16 with a male thread formed on the outer periphery is screwed into the lower side of the crankcase 13. The switching cock 17 has a common passage 18 for drain oil and internal pressure that communicates with the inside of the crank chamber, and branches the common passage 18 into a drain oil passage 19 and an internal pressure take-out passage 20, and a cylindrical space 21 is provided in this branch. A cylindrical valve body 22 is interposed therebetween so as to be freely rotatable. This valve body 22 is formed with a switching passage 23 that selectively communicates the common passage 18 with the drain oil passage 19 or the internal pressure extraction passage 20. The switching passage 23 includes a first passage 23a penetrating the opposing outer peripheral surface of the valve body 22, and a second passage 23a having one end that intersects with this passage 23a and opening and the other end opening to the outer peripheral surface of the valve body 22. For example, it is formed in a substantially T-shape from the passage 23b. Further, the operating portion 24 of the valve body 22 projects flatly from the upper part of the switching knob 17, and the operating portion 24 extends in the direction of the first passage 23a penetrating the opposing outer peripheral surface of the valve body 22. The valve body 22 is configured to indicate whether the valve body 22 is switched to the oil drain passage 19 or the internal pressure extraction passage 20.

The oil drain passage 19 of the switching pot 17 is open to the outside as it is, while the internal pressure extraction passage 2
0 communicates with an internal pressure introduction part 27 in the fuel pump of the carburetor 15 via a press-fitted joint 25 and a conduit 26 connected to the joint 25.

In addition, the reference numeral 28 in the drawing is the packing of the switching cock,
29 indicates a fixing nut.

In such a configuration, the oil drain passage 19 and the internal pressure take-out passage 20 can be selectively switched to either one by rotating the valve body 22, so that the oil drain passage can be left open. This makes it possible to avoid oil draining work while the engine is running and the crank chamber is in communication with the carburetor fuel pump. In other words, if you forget to turn the fuel tank and try to start the engine in the conditions shown in Figure 5 A and B, the carburetor pump will not operate because there is no negative pressure from the crankcase, and you will forget to turn the fuel tank. It has an immediately obvious effect. Further, the switching state between the oil drain passage 19 and the internal pressure extraction passage 20 is instructed by the operating section 24 of the valve body 22.

As explained above, according to the present invention, it is possible to prevent the crank chamber oil drain pot from being forgotten to close, thereby eliminating malfunction of the carburetor fuel pump and leakage of raw gas from the crank chamber drain pot. This has the effect of automatically cutting off the communication between the crank chamber and the carburetor fuel pump when oil is present, thereby preventing the supply of fuel due to the operation of the fuel pump when the oil is being drained.

[Brief explanation of the drawing]

Figures 1 and 2 show conventional examples, and Figure 1 shows 2
A front view of the cycle engine, Figures 2A, B, and C are respectively a front view of the oil drain pot, a sectional view of the oil drain pot in the open state, a sectional view of the oil drain pot in the closed state, and Figures 3 to 6. 3 is a front view showing a two-stroke engine, FIGS. 4A and B are front and side views showing the switching cock, and FIGS. 5A and B are views on the oil drain side. FIGS. 6A and 6B are a cross-sectional view and a plan view of the switching socket in the switched state, and FIGS. 6A and 6B are a sectional view and a plan view of the switching socket in the switched state. 11... 2-cycle engine body, 13... Crank case, 15... Carburetor with fuel pump, 1
7... Switching point, 18... Common passage, 19...
Oil drain passage, 20...internal pressure extraction passage, 22...valve body.

Claims (1)

[Scope of utility model registration request] In a two-stroke engine equipped with a carburetor with a fuel pump that operates by the alternating action of positive and negative pressure in the crank chamber to introduce fuel, a switching point is attached to the lower side of the crankcase, and this switching point is connected to the crank chamber. A common passage for drain oil and internal pressure is provided which communicates with the drain passage, the common passage is branched into an oil drain passage and an internal pressure take-out passage, and a valve is provided at the branched portion that can be selectively switched to either the oil drain passage or the internal pressure take-out passage. A crank chamber exhaust oil for a two-cycle engine, characterized in that the internal pressure outlet passage of the switching cock is connected to a carburetor fuel pump via a conduit.
Internal pressure extraction passage switching device.