JPH0257209B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes a high-load passage and a wide-area passage each connected to a combustion chamber via an intake valve, and the high-load passage is provided with an air valve that closes during low-load operation. This relates to the intake system of multi-cylinder engines.
In particular, the present invention relates to an improvement in an operating device for opening and closing the air valve.

Conventionally, an engine having two types of intake passages, a high-load passage and a wide-area passage as described above, is known (for example, Japanese Patent Laid-Open No. 51920/1983). Since the air valve is generally a butterfly valve, if the engine has multiple cylinders, the valve stem of the air valve must pass through the intake pipes of other cylinders. Therefore, the valve stem becomes long, and high-precision machining is required to form the shaft hole of the valve stem. The present invention has the advantage that, in order to avoid the need for high precision in machining such shaft holes, the valve shafts are made short and small for each cylinder or two, and they are connected by a shaft coupling with a simple structure. It has characteristics.

Hereinafter, the present invention will be explained with reference to illustrated embodiments.

Reference numeral 1 designates an engine body of a water-cooled in-line six-cylinder engine, which has a combustion chamber 5 formed by a cylinder 2, a cylinder head 3, and a piston 4. Two intake valves 6 and 7 are installed in this combustion chamber 5. The high load passage 8 is connected to the exhaust passage 11 through the wide range passage 9 and the exhaust valve 10. 12 is a spark plug, and 13 is a conventionally known twin cam type valve mechanism. Reference numerals 15 and 16 indicate intake ports forming intake passages 8 and 9 within the cylinder head 3, and an air valve 17 and an intake branch pipe 18 are connected to openings on the side surfaces of the cylinder head 3. The air valve 17 has a valve body 17a
and a valve shaft 17b that passes through the valve body, and this valve shaft 17.
It is composed of a butterfly-shaped valve body 17c supported by b. The intake branch pipe 18 is formed by connecting a branch pipe 18a and a collecting part 18b with a distribution box 18c, and the collecting part 18b is provided with a throttle valve 19 that is manually operated. In this way, the intake ports 15, 16, the valve body 17a, and the intake branch pipe 18 constitute a series of intake passages that communicate the combustion chamber 5 to the atmosphere. 20 is a through hole communicating between the intake ports 15 and 16;
1 is a fuel injection nozzle.

The air valve 17 is controlled to open and close by a dial ram 22 that responds to the intake negative pressure generated downstream of the throttle valve 19. The dial ram 22 includes an atmospheric chamber 22b that communicates with the atmosphere through a bullet film 22a, and a throttle valve 19.
It is divided into a negative pressure chamber 22c communicating with the intake passage on the downstream side. Reference numeral 22d denotes a rod provided on the elastic membrane 22a, and is biased toward closing the air valve 17 by a spring 22e. The other end of the rod 22d is connected to the arm 1 fixed to the end of the valve shaft 17b.
7d. So, dialer lum 2
2 closes the air valve 17 during low load operation when the intake negative pressure generated downstream of the throttle valve 19 is high (pressure is low). One valve body 17a is installed for each two cylinders, and as shown in FIG. 3, it consists of L for the left cylinder, M for the middle cylinder, and R for the right cylinder, which are connected to each other by brackets 23 and bolts 23a. are connected together. Connection between each valve shaft 17b is made by an arm 17d between L for the left cylinder and M for the middle cylinder, and
A shaft coupling 24 connects M for the middle cylinder and R for the right cylinder. As shown in FIG. 5, the shaft joint 24 consists of notched grooves 25 formed at mutually opposing ends of each valve shaft 17b and a synthetic resin connecting member 26 interposed between them. The connecting member 26 is composed of an outer cylinder 26a and two integrally molded plate-shaped locking pieces 26b disposed criss-cross inside the outer cylinder, and the plate-shaped locking pieces 26b are integrally molded. 26
b is removably engaged with the notched groove 25. That is, the combination of these locking pieces 26b and the notched grooves 25 provides an Oldham type shaft joint structure. 27 is a return spring provided between the pin 28 press-fitted into the valve body 17a and the protrusion 26c of the connecting member 24, and 29 is a dustproof seal.

Next, the operation of this engine will be explained. When the engine starts and the throttle valve 19 is operated at a low opening,
Since the intake negative pressure generated in the downstream intake passages 8 and 9 is high (pressure is low), the air valve 17 closes the high-load passage 8, and the entire amount of intake air passes only through the wide area passage 9 to the combustion chamber 5. This results in a high intake flow rate and good acceleration response for the engine. When the load on the engine increases and the opening degree of the throttle valve 19 reaches a higher opening degree than expected, the intake negative pressure generated in the intake passages 8 and 9 downstream thereof becomes low (high pressure), and the air valve 17 is under high load. The combustion passage 8 is opened, and the main combustion air is guided into the combustion chamber 5 through both intakes. That is, since the area of the intake passage can be made sufficiently large, ventilation resistance is reduced, and a large output can be obtained from the engine. Here, since the valve shaft 17b of the air valve 17 is divided into three parts, each valve body 17
The length of the shaft hole a is not unnecessarily long, and the machining can be easily performed. Moreover, since an Oldham-type shaft joint is formed between each valve shaft 17b, which is composed of a notched groove 25 formed at the end thereof and a connecting member 26 made of synthetic resin, even if the shaft hole of each valve body 17a is Even if the machining accuracy of the parts is not appropriate, even if their concentricity is disturbed by the heat of the engine, and even if the assembly accuracy is not appropriate, they will operate smoothly. The main cause of combustion variation between cylinders is the air intake passage and valve body 1 when the air valve is inactive.
There are variations in the amount of air leaking from the gap with 7c. Therefore, it is necessary to ensure that the valve bodies 17c of all cylinders are closed with a predetermined gap when the air valves are not in operation. Therefore, using FIG. 5 as an example, if the return spring 27 eliminates the looseness between the left valve stem 17b and the shaft coupling 26, the right valve stem 17b and the shaft coupling 26 will fit together. Due to the relationship settings, when the left valve body group is closed, the right valve body group also closes the intake passage. In other words, the return spring 27 biases the play between the right valve shaft 17b and the shaft coupling 26 only in the direction in which the valve body closes, so that the air valve that most affects the combustion variation between cylinders is inoperative. It is possible to reduce variations in the amount of air at different times.

As explained above, this invention includes a plurality of air valves each consisting of a valve body and a spiral valve body supported by a valve stem passing through the valve body, which are attached to the side of an engine body, and the valve stem is connected to the valve body. In the valve shafts arranged concentrically and connected by a shaft joint, since the valve shafts are connected via a connecting member that constitutes an Oldham-type shaft joint structure together with the end of the valve shaft, The structure is simple, the number of parts is small, and there is no need to strictly control processing or assembly accuracy, so it can be manufactured at low cost. Further, the valve body and valve stem can be easily machined compared to a large-sized one in which each air valve passes through the intake passage of each cylinder. Furthermore, since a return spring that biases the coupling member in the rotational direction is interposed between the coupling member and the valve body, the gap between the coupling member and the valve shaft is absorbed by the biasing force of this spring. Therefore, there is an advantage that so-called rattling is eliminated, the opening and closing of a plurality of valve bodies can be synchronized, and variations among cylinders are reduced.

[Brief explanation of the drawing]

The drawings show one embodiment of the invention,
Figure 1 is a side view of the engine with main parts broken away, Figure 2
The figure is a partially cutaway plan view, and Figure 3 is -
4 is an enlarged sectional view showing the cross section, FIG. 5 is an exploded perspective view of the main parts, FIG. 6 is a front view of the connecting member 26, and FIG. 7 is its -
The sectional view and FIG. 8 are rear views. 17...Air valve, 18...Intake branch pipe, 19...
... Throttle valve, 22 ... Diaphragm, 24 ... Shaft joint, 25 ... Notch groove, 26 ... Connection member.

Claims (1)

[Claims] 1. A plurality of air valves 17 each consisting of a valve body 17a and a butterfly-shaped valve body 17c supported by a valve shaft 17b passing through the valve body are attached to the side of the engine body,
The valve shafts 17b are arranged concentrically and the valve shafts are connected by a shaft coupling, in which the valve shafts 17b are connected concentrically.
7b and 17b are connected together with the end of the valve shaft via a connecting member 26 that constitutes an Oldham type shaft coupling structure, and the connecting member is biased in the rotational direction between this connecting member and the valve body 17a. A pneumatic valve operating device for a multi-cylinder engine that includes a return spring 27.