GB2227055A

GB2227055A - Two-stroke diesel engine

Info

Publication number: GB2227055A
Application number: GB8900759A
Authority: GB
Inventors: Kunito Taguma
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-01-13
Filing date: 1989-01-13
Publication date: 1990-07-18
Also published as: GB8900759D0

Abstract

The cylinder head exhaust valve 14, 16 has the fuel supply tube 28 centrally located therein. The cylinder 2 has air inlets 8 and the piston 6 a concave upper surface 30. <IMAGE>

Description

Title of the Invention Diesel Engine Cylinder Mechanism Background of the Invention Field of the Invention This invention relates to a diesel engine cylinder ae- chaise and, nore particularly, to a diesel engine cylinder mechanism, which permits reduction of the cylinder size and prolongation of the cylinder life.

Prior Art In a cylinder of a prior art automotive two-cycle diesel engine, for instance, with the cylinder wall provided with a plurality of air inlet holes communicating with the cylinder interior when the piston is at the bottom dead center, an exhaust valve and a fuel supply tube ith an injection valve are provided separately on the cylinder.

Also, the piston has a flat upper end surface.

The provision of the exhaust valve and fuel supply tube with injection valve separately on the cylinder as in the prior art dictates size increase of the cylinder itself. In addition, the cylinder has to be formed with two counting holes for mounting the exhaust valve and fuel supply tube with injection valve. Therefore, at least double the ian- holrs - required for manufacturing the cylinder and ensur ins the air tightness.

Further, since the piston has a flat upper end surface, the pressure of explosion at the tire of ignition by coapression is strongly directly applied to the cylinder periphery. Thus, it is liable to cause damage to the peripheral wall of the cylinder, thus reducing the cylinder life.

Sugary of the Invention The present invention has been intended in the light of the problens described above in the prior art diesel engine cylinder mechanism. The inventor contenpiated that the above problems can be solved by providing an exhaust valve such that it extends fron the center of the upper end wall of the diesel engine cylinder into the cylinder, having the lower end of a fuel supply tube with injection valve inserted through and secured to the center of the exhaust valve and preferaly also by fo-ming a cup-shaped concave upper end surface of the piston. The invention is predicted in this contelpiation.

A Urinary object of the invention is to provide a diesel engine cylinder mechanism, which peraits reduction of the cylinder size.

A second object of the invention is to provide a diesel engine cylinder mechanism, which permits extreme reduction of the man-hours required for the nanufacture of the cylinder and securing air tightness, thus contributing to the cost reduction.

A third object of the invention is to provide a diesel engine cylinder mechanism, which permits damage avoidance to the cylinder periphery and prolongation of the cylinder life.

The above and other objects and novel features of the present invention will become adore apparent when the following detailed description is read with reference to the accompanying drawing. The drawing is for the purposeo of illustration only and not sense of limiting the invention.

Brief Description of the Drawing Fig. 1 is a scheiatic elevational sectional view showing a diesel engine cylinder mechanism according to the invention Description of the Preferred Embodiment Referring to Fig. 1, reference numeral 2 designates a diesel engine cylinder. The peripheral wall 4 of the cylinder 2 has a plurality of air inlet holes 8 which oavunicate with the interior of the cylinder 2 when the piston 6 is at the bottoi dead center (the piston 6 being shown in Fig. 1 at the top dead center at the tire of ignition by co.pression).

The upper end wall (cylinder head) 10 of the cylinder 2 has a central vertical guide hole 12. A guide pipe 16 with an exhaust valve 14 secured to the lower end vertically movably penetrates the guide hole 12. The guide pipe 16 is biased by a coil spring 20 fitted on the outer periphery of the guide pipe 16 with the upper and lower ends secured to the top of the upper end wall 10 of the cylinder 2 and upper flange 18 of the guide pipe 16. The guide pipe 16 is operable by the cauls 22 rotated by a synchronization control mechanism (not shown) such that it executes a constantfrequency vertical reciprocation to descend against the spring force of the coil spring 20 and ascending by the spring force of the coil spring 20.

With the constant period vertical reciprocation of the guide pipe 16 with the compression and elongation of the coil spring 20 caused by the cans 22, the exhaust valve 14 secured to the lower end of the guide pipe 16 continuously opens and closes at a constant frequency an opening 26 of the stei of an exhaust air passage 24 extending fros the lower portion of the guide hole 12 of the cylinder 2 toward one side of the upper end wall 10 of the cylinder 2.

A fuel supply tube 28 with an ignition valve coaxially extends through the guide pipe 16 with its lower end penetrating and secured to the center of the exhaust valvc 14.

Thus, there is no need of forcing the cylinder 2 with two mounting holes for bunting the exhaust valve 14 and fuel supply tube 28 with ignition valve, but it is necessary to forn only a single guide hole 12. The upper end face of the piston 6 has a cup-shaped concave surface 30. The pressure of explosion at the tine of ignition by coepression can be first applied to the center of the cup-shaped concave surface 30 and then progressively dispersed along the concave surface toward the edge thereof.

The operation of the other partsof the cylinder mechanism is the sane as in the prior art.

As has been shown in the foregoing, with the diesel engine cylinder according to the invention the upper end wall of the cylinder is provided with a central guide hole, through which a guide pipe with an exhaust valve is inserted. Thus, the exhaust valve and fuel supply tube with an ignition valve can be sinultaneously mounted in the sane place, thus Permitting size reduction of the cylinder and greatly reducing ean-hour for the nanufacture of the cylinder and assuring air-tightness.

Besides, with the piston provided with a cup-shaped concave upper end surface, the pressure of explosion at the tile of the ignition by conpression can be first applied to the center of the cup-shaped concave surface and dispersed along the cup-shaped concave surface toward the edge thereof.

Thus, no pressure of explosion is directly applied to the cylinder periphery, thus eliainating damage to the cylinder periphery contributing to the extension of the cylinder life.

It is obvious that various nodifications of the above construction are possible without departing fron the scope of the invent ion, and the described forn of invention is by no leans linitative except for definition by the annexed clan.

Claims

1. A diesel engine cylinder mechanism with the cylinder periphery formed with a plurality of air inlet holes coinunicating with the cylinder interior when the piston is at the bottom dead center, in which said cylinder has an upper end wall with a central guide hole, a guide pipe with an exhaust valve secured to the lower end penetrates said guide hole for vertical eoverent in said cylinder, said exhaust valve opens and closes an opening of the sten of an exhaust air passage extending from the lower portion of the guide hole of the cylinder toward one side of said upper end wall, a fuel supply tube with an ignition valve penetrates said guide pipe and has a lower end inserted through and secured to the center of said exhaust valve to be exposed to the cylinder, and said piston has a cup-shaped concave upper end surface.

2. A diesel engine cylinder mechanism with the cylinder periphery formed with a plurality of air inlet holes communicating with the cylinder interior when the piston is at the bottom dead centre, in which said cylinder has an upper end wall with a central guide hole, a guide pipe with an exhaust valve secured to the lower end penetrates said guide hole for vertical movement in said cylinder, said exhaust valve opens and closes an opening of the stem of an exhaust air passage extending from the lower portion of the guide hole of the cylinder toward one side of said upper end wall, and a fuel supply tube with an ignition valve penetrates said guide pipe and has a lower end inserted through and secured to the centre of said exhaust valve to be exposed to the cylinder.

3. A mechanism according to claim 2, wherein said piston has a cup-shaped concave upper end surface.

4. A diesel engine cylinder mechanism as claimed in claim 1 or claim 2, substantially as herein described with reference to and as shown in the accompanying drawing.