GB2248652A

GB2248652A - Twin bank i.c. engine intake arrangement

Info

Publication number: GB2248652A
Application number: GB9021807A
Authority: GB
Inventors: Manabu Sugai; Yasuo Hiraoka
Original assignee: Fuji Jukogyo KK; Fuji Heavy Industries Ltd
Current assignee: Subaru Corp
Priority date: 1989-10-12
Filing date: 1990-10-08
Publication date: 1992-04-15
Also published as: DE4032321A1; GB9021807D0

Abstract

The two intake manifold chambers 7a are supplied from a common intake pipe 3 and surge tank 4 through respective passages in a throttle body 5. The chambers 7a may communicate through a passage 7b under the control of a valve 8 closed at low engine speed. The chambers 7a are inclined relative to the engine axis (Fig. 4) to accommodate a sloping vehicle bonnet and the manifold branch pipes 10, 11 have varying shapes to equalise their lengths. Passages for air flow by-passing the throttle valves 6 are formed in the throttle body 5 which supports valves (20, 21 (Fig. 5)) for controlling the by-pass passages. <IMAGE>

Description

1 INTAKE DEVICE OF AN ENGINE The present invention relates to an intake

device of 5 an engine, and more particularlyy to an intake device -that is particularly suitable for 6-cylinder engines having two banks of three cylinders in a horizontally opposed arrangement-or a V-arrangement.

There is known (as for example, in Japanese Patent Laid-open Pu b. No. 60-62654) an intake device of an engine of the type having two banks of three cylinders. The en gine is provided with two sepatate intake chambers -(surge tanks) corresponding to the respective banks. The engine is also provided with two separate throttle bodies that communicate with the intake chambers, respectively.

In the device described above,, the throttle bodies respectively house throttle valves and are disposed in sp aced-apart relation so as to cooperate with the corresponding banks. The throttle bodies communicate with a common chamber at separate portions thereof, which communicates with an intake pipe.

In such an engine intake devicer depending upon the position of the connection of the intake tube to the chamber, the intake length upstream from one of the two throttle bodies is not equal to the intake length upstream from the other of the two throttle bodies. Therefore, 1.5 component intake noise generated inside each of the intake chambers (surge tanks) cannot be suppressed by interference so that intake noise is emitted to the outside.

In addition, the link mechanism for operating the throttle valves are complex because the two throttle bodies are separated, and furthermorer there is the problem of inconvenience of the outfitting since each of the throttle bodies has to be separately assembled and fitted.

2 In recent moeor vehicles, the engine room is relatively small so as to make the vehicle interior larger so that there is a restriction to the entire length of the engine. Furthermore, there is also a limit to the height of the eng ' ine hood so that the height of -the engine is also restricted. Accordingly, when an engine provided with a normal intake device is to be mounted on a motor vehicle, it is difficult to house the engine inside the engine room, and this is an undesirable situation designwise. - A con7entional engine intake device is provided with an idling speed control (ISC) valve in an idle bypass passage in order to control the idling speed of the engine, a valve for -a fast idling control device (FICD) in order to prevent the engine speed from falling when an air conditioner is operated, an air regulator valve provided in a bypass passage in order to secure the air regulator functions when the engine is cold-started, and a canister purge passage. Each of these passages is provided to bypass the throttle valves.

In such a conventional intake devicer two throttle bodies are spaced so that there is the tendency for the passage system to-.become complex. Because of thisi. the weight of the passage system increases and outfitting is inconvenient. Moreover, there is the problem of deteriorating distribution of the auxiliary air to the suction passages for each bank.

The main object of the present invention is to provide an intake device of an engine wherein e_ternal dissipationof intake noise is prevented by interference of the 1.5 component intake noise generated inside each of the intake chambers, wherein the link mechanism for operating the throttle valves is simplified and wherein the outfitting or installation characteristics of the throttle body is improved.

3 Another object of the present invention is to provide an engine intake device that is suitable for installing in an engine room having a hood inclining to be lower towards the front side.

In order to achieve the main object,, according to --the present inventionr there is provided an intake device of an engine with two banks of cylinders, said device.comprising: intake pipe, a single surge chamber connected to the intake pipe for receiving intake air from the intake pipef a throttle body having therein parallel suction passages disposed adjacent to each other and communicating with said surge chamber so as to receive air from the chamber, throttle valves provided in said suction passages, respectively, and two intake manifolds provided for the banks of cylinders., respectively, each of the intake manifolds having an intake chamber which communicates with one of said suction passages,, and a plurality of inlet pipes communicating the intake chambers with the respective cylinders.

In the intake device according to the present invention, the two suction passages of the throttle body are adjacent to each other and communicate with the surge chamber so that the lengths of the suction paths upstream of the suction passages become approximately equal irrespective of the position of connection of the intake pipe to the surge chamber. Accordingly, the 1.5 component intake noise generated inside the intake chambers causes interference inside the chambers and is muffled so that the external dissipation of intake noise is prevented.

In addition, the two suction passages are adjacently provided in the throttle body whereby the link mechanism for operating the throttle valve is simplified and the outfitting on the throttle body is facilitated since there is only one throttle body.

4 Preferred embodiments of the present invention will become understood from the following. detailed description, referring to the accompanying drawings.

FIG. 1 is a plan view of an intake device of an according to the present invention; FIGS. 2 and 3 are fragmentary horizontal sectional views indicating respectively different statuses of the intake device; 10- FIG. 4 is a-vertical sectional view as seen from the right-hand side of FIG. 1; FIG.. 5 is a view as seen in the direction indicated by the arrow V in FIG. 1, with a box-shaped surge chamber removed; FIG. 6 is a view as seen from the underside of FIG.

5; FIG. 7 is a view as seen in the direction of the arrow VII in FIG. 5; FIG. 8 is a view seen in the direction of the arrow VIII in FIG. 5; FIG. 9 is a view showing an intake passage passing through an ISC valve; and FIG. 10 is a view showing another passage system passing through a FICD valve and a regulator valve.

FIG. 1 indicates a six-cylinder engine of the horizontally-opposed typer to which the present invention is'applied. As shown in the figurer the engine E has two banksr each including the cylinders. Two intake manifolds 7 are provided for respective banks. Each intake manifold 7 - comprises an intake chamber 7a and three inlet pipes_.10ar 10br 10c (11a.. 11br 11c) connecting the intake chamber 7a to the respective cylinders. An intake tube 3 is connected to a downstream side of an air cleaner 1 via an air flow meter 2. and a downstream end of the intake tube 3 communicates with a box-shaped surge chamber 4 having a predetermined capacity. A side'. wall of this surge chamber 4 is communicatively connected with the downstream end of the intake pipe 3. and an adjacent side wall of the chamber 4 is connected to a throttle body-5.

As shown in FIG. 2, the throttle body 5 is -interiorly formed with two adjacent parallel suction passages 5a leading to the respective banks of the engine E with three cylinders on each side. The suction passages 5a -respectively have two throttle valves 6 that open and close the respective passages 5a. The throttle valves 6 are fixed on the same rotating shaft 6ar and therefore the necessary link mechanism 6b is simpler than the case where the two throttle valves are provided separately in spaced-apart arrangement so that the throttle valves 6 are operated easily.

In each of the suction passages Sa f ormed in the throttle body 5, the upstream side communicates with the surge chamber 4 and the downstream side thereof communicates with the intake chamber 7a via connecting passages 5b formed in the intake manifold 7. Each intake chamber 7a is defined._in a housing as shown. The connecting passages 5b become more spaced from each other as they extend towards the intake chambers 7a.

The intake chambers 7a mutually communicate via communication passage 7b that is opened and closed by a variable intake valve 8. The variable intake valve 8 operates so as to close the communication passage 7b as indicated in FIG. 2r when the engine is operating at low speed, and so as to open the communication passage 7b as indicated in FIG. 3, when the engine is operating at high speed.

As described above, in the intake device, the two suction passages 5a are formed adjacently in the throttle body 5, so that the throttle valves 6 can be fixed adjacently to the same rotating shaf t 6a. Accordingly,, the link mechanism 6b for operating the throttle valves 6 is simplified. In addition, since there is only one 6 throttle body 5, -the intake device can be easily outfitted to the intake manifolds '_and the surge chamber 4 than the conventional intake device that requires two throttle bodies.

The engine intake device having the above feature -performs supercharge with resonance due to the variable intake valve 8 closing the communication passage 7b as indicated in FIG. 2. More specifically, the suction passages 5a- of the throttle body 5 become resonance passages so that when each of the cylinders of the engine successively performs intake,, the pressure wave of the intake air generated inside the intake chambers 7a is in phase with the frequency of natural vibration of the intake device, whereby a large supercharging effect is obtained.

When the engine is operating at high speed, the variable intake valve 8 opens the communication passage 7b as indicated in FIG. 3 so that air is induced into each of the cylinders of the engine f rom not only one intake chamber 7a but also the other intake chamber 7a via the communication passage 7b.

Let us consider the 1.5 component intake noise that is generat.ed inside each of the intake chambers 7a while the engine is operating. The 1.5 component intake noise has the wave of 1.5 period for one rotation of the engine. Since the two suction passages 5a formed in the throttle body 5 are adjacent to each other and communicate with the surge chamber 4 of predetermined capacity, and since' the both intake lengths on the upstream side from the suction passages 5a are approximately the samej, the 1.5 component intake noise has interference inside the surge chamber 4 and is muffled, whereby intake noise dissipation to the outside is prevented.

As shown in FIG. 4, the upper edge portion 7al of each of the intake chambers 7a is inclined so as to become lower in a direction away from the throttle body 5 7 towards the f ront Of the vehicle, thus corresponding to the shape of an engine hood 12 of the vehicle. Furthermore,, as indicated in FIG. 1,, the side surfaces 7a2 of the intake chambers 7a are inclined so that the end part having the suction tubes 10C and 11C is further out with respect to the centerline (crankshaft line) of the engine E, than is the end part having the suction tubes 10a and lla.

The inlet pipes 10a, 10b and 10c (11a, llb and llc) 10- are arranged such that the respective centers a, b and c (FIG. 4) of openings at which the inlet pipes 10a,, 10b and 10c (11a, llb and llc) are joined to the side surface 7a2 are on a lines e-e parallel to the upper edge 7al. A combination of-vertical tubes and horizontal tubes 15 is used for forming the inlet pipes 10a, 10b and 10c (11a, llb and llc). The inlet pipes are arranged such that the sums of the lengths of the horizontal portions (the portions indicated in FIG. 1) and the vertical portions (the portions indicated in FIG. 4) of the inlet 20 pipes 10a, 10b, 10c and lla. llb. llc are equal. For examplel when the inlet pipes 10a, 10b, 10c of the bank on one side have respective lengths el, 'e2F 'e3 of the horizontal portions extending beyond the side surface 7a2 of the intake chamber 7a, as shown in FIG. 1, and when the lengths of the vertical portions of the inlet pipes 10a, 10by 10c are made h,, h2t h3f respectively, as shown in FIG. 4r then the horizontal portions and the vertical portions are formed to have the following relationship. 30 el + h, = 0 2 + h2 = 0 3 + h3 In the intake device as described above. the lengths of the inlet pipes 10ar 10br 10c and lla. llb. llc that distribute the air from the intake chambers 7a to each of the cylinders are approximately equal, so that the intake efficiency is made uniform and the intake inertia effect of the engine improves the performance at low engine 8 speed. In additiori- the combustion at low engine speed 7.

is improved and exhaust emission becomes stable.

FIG. 5 is a view of the throttle body 5 of FIG. ll as seen in the direction of the arrow V in FIG. 1. In FIG. 5, a throttle switch 29 is mounted on the side of the throttle body 5 in order to detect open/closed status of the throttle valve 6. In addition, an idle speed control (ISC) valve 20 is mounted on the lower surface of the throttle body 5 and a valve 21 of a fast idle control device (FICD) is mounted on the top surface thereof.

The ISC valve 20 is f ixed by bolts to a position midway between the two suction passages 5a of the throttle body 5. As indicated in FIG. 9, the ISC valve 20 communicates via- a connection elbow 301 with an upstream portion 31U of an idle bypass passage 31 that communicates with the intake pipe 3. As indicated in FIG. 6 showing the underside of the device shown in FIG. 5, the throttle body 5 has downstream portions 31D of the idle bypass passage 31, connecting the ISC valve 20 with the suction passages 5a. as shown in FIG. 9. As FIG. 6 shows, the downstream portions 31D branch symmetrically and are connected to portions downstream from the throttle valves, 6 of the suction passages Sa. respectively.

As indicated in FIG. 8. on the side of the throttle body 5r opposite to the ISC valve 20F there are provided a FICD bypass passage 32r a regulator bypass passage 33 and a canister purge passage 24. The FICD bypass passage 32 communicates with the intake pipe 3 via a valve of a fast idle control device (FICD). The regulator bypass passage 33 is connected to the air regulator valve 22 (FIG. 10) via a nipple 35. and the canister purge passage 24 is connected to a canister (not shown) via a nipple 36. The regulator bypass passage 33 and the canister purge passage 24 are formed in a line that perpendicularly crosses the suction passages 5a, and the FICD bypass passage 32 is formed along the suction 9 passages 5a and coihected to the canister purge passage 24. Passages 37 branch symmetrically from a portion where the canister purge passage 24 communicates with the regulator bypass passage 33 and connected to portions downstream from the throttle valves 6 of the suction.-passages 5a, respectively. As shown in FIG. 6, the passages 37 are disposed at the opposite side of the idle bypass passage 31D with respect to the suction passages Sa. The FICD valve 21 is mounted to the side wall of the throttle body 5 to open and close the FICD bypass passage 32.

When the engine in a cold state is started, the air regulator valve 22 opens the regulator bypass passage 33 so that auxiliary air is taken in, bypassing the throttle valves 6 and the air regulator function is performed. When the engine is running in an idling state, the ISC valve 20 is operated to control the quantity of -the air flow that passes the idle bypass passage 31 so as to hold a suitable idling engine speed. vaporized fuel that is sucked into the canister is taken into the suction passages 5a via the canister purge passage 24.

When the air conditioner is operated, the FICD valve 21 opens the FICD b ypass passage 32 and auxiliary air is sucked into the suction passages 5a at a downstream position of the throttle valves 6, via the canister purge passage 24r so as to prevent the engine speed from dropping.

As described above, the FICD valve 21 and the ISC valve 20 that constitute an auxiliary air system are incorporated to the throttle body 5, and the throttle body 5 is formed combinedly with the downstream portions 31D of the idle bypass passagef the FICD bypass passage 32, the regulator bypass passage 33 and the canister purge passage 24. Thereforer the structure of the auxiliary air passage system is simple, and it is possible to reduce the weight of the intake device and also to facilitate outfitting.

The bypassing iuxiliary air passages described above are in communication with the downstream side of the throttle valves 61. so that an improved distribution performance is obtained for the auxiliary air.

While the presently preferred embodiments of the present invention have been shown and described, it is to be understood that the disclosure is for the purpose of illustration and that various changes and modifications may be made 'without departing from the scope of the invention as set-forth-in the appended claims.

11

Claims

CLAIMS:

1 An intake device of an engine having two banks of cylinders and an intake portr characterized by:

intake pipe communicating with said intake port; a single surge chamber connected to the intake pipe for inducing intake air from the intake pipe; a- throttle body having therein parallel suction passages disposed adjacent to each other and communicating with said surge chamber so as to receive air from the.chamber; throttle valves provided in said suction respectively; and - two intake manifolds - provided f or the banks of cylinders, respectively, and having therein respective intake chambers which communicate with said suction passagesr respectively; and a plurality of inlet pipes communicatively connecting the. intake chambers with the respective cylinders.

passages,

2. The intake device according to claim 1, wherein said surge chambez is box-shaped.

3. The intake device according to claim 1, further comprising two connecting passages connecting the suction passages to the intake chambers of said manifolds, respectively, said connecting passages being arranged to become more spaced f rom each other as they extend towards the manifolds.,

4. The intake, device according to claim 11, wherein said intake chambers have upper edges inclining downward to ward the f ront of the engine, and side surfaces - - - - inclining inwardly with respect to a centerline between the intake chambers toward the front 12 of the engine,, and---+Whereinsaid inlet pipes -have the same length.

5. The intake device according' to claim 4 wherein an inclined angle of te upper edges is equal to an -inclined angle of an engine hood.

6. The intake - device according to claim 4, wherein each of said inlet tipes comprises a horizontal portion ('el-'e3 extending from the intake chamber, and a vertical portion (h,-h3) extending downwards from the horizontal portion so as to lead to one of the cylinders, the inlet pipes having longer horizontal portions and shorter vertical portions as the inlet pipes are farther from the throttle body.

7. The intake device according to claim 1, further comprising bypass means outer walls of said throttle body provided on and connecting said intake pipe with the suction passages positions downstream of the throttle valves bypass the throttle valves, and adjusting means mounted on sa-id outer walls for adjusting air flow passing through the bypass means.

at so as to

8. The intake device according to claim 7. wherein said bypass means comprise an idle bypass passage, a fast idle control bypass passage, a regulator bypass passage. and a canister purge passagej. and wherein said adjusting means comprises an idle-speed control valve mounted on said idle bypass passager a fast idle control Valve disposed in said fast idle control bypass passage, and a regulator valve provided on said regulator bypass passage.

g. The intake device according to claim 8, wherein said idle speed control valve and said f ast idle 13 control valve are mounted on the outer walls of the throttle body on the opposite side of the body.

10.1 An intake device of an engine zu.bstantially as hereinbeforedescribed with.reference toand as shown in the accompanying drawings.