Europaisches Patentamt (19) European Patent Office Office europeenpeen des brevets EP 0 499 268 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention (51) intci.e: F02F 1/42, F02B 61/02 of the grant of the patent: 08.05.1996 Bulletin 1996/19 (21) Application number: 92102501.1 (22) Date of filing: 14.02.1992 (54) Multiple valve internal combustion engine Vielfachventilbrennkraftmaschine Moteur a combustion interne a multiples soupapes (84) Designated Contracting States: (72) Inventors: DE ES FR GB IT Kaneko Mamoru 2500 Shingai Iwata-Shi Shizuoka-Ken 438 (JP) (30) Priority: 15.02.1991 JP 44310/91 Nonogawa Kenichi 2500 Shingai Iwata-Shi Shizuoka-Ken 438 (JP) (43) Date of publication of application: 19.08.1992 Bulletin 1992/34 (74) Representative: Griinecker, Kinkeldey, Stockmair & Schwanhausser Anwaltssozietat (73) Proprietor: YAMAHA HATSUDOKI KABUSHIKI Maximilianstrasse 58 KAISHA 80538 Miinchen (DE) Iwata-shi Shizuoka-ken, 438 (JP) (56) References cited: US-A- 4 627 400 US-A- 4 683 855 DO 00 CO CM O) O) ^- Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice the Patent Office of the Notice of shall be filed in o to European opposition to European patent granted. opposition a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. a. 99(1) European Patent Convention). LU Printed by Jouve, 75001 PARIS (FR) 1 EP 0 499 26858 B1 2 Description connecting passage is arranged perpendicularly with re- spect to the direction of flow of the fluid. The present invention relates the multiple valve in- Further examples of staged induction systems are ternal combustion engine comprising a cylinder head disclosed in US-A-4617896, US-A-4683855, JP-A- having at least three intake valves per cylinder and a s 61186726 and JP-A-62-93122. Moreover, by means of staged induction system having at least two intake pas- constructional measures attempts have already been sages serving the intake valve seat openings of the cyl- made to improve the volumetric efficiency of charging inder head and charge forming means and an intercon- the combustion chamber, providing a good turbulence necting passage connecting at least two of said intake and swirl action of the charge introduced therein (US-A- passages. 10 4971008, JP-A-63-25369, JP-A-1 -1 39079, JP-A- It is acknowledged that the performance of an inter- 1-95572, JP-A-62-12771, EP-A-430258, EP-A-430259, nal combustion engine can be improved, particularly at EP-A-430263). high speeds, by the use of multiple intake valves. Al- As such an intake device in which a swirl is obtain- though four valve per cylinder engines are quite com- able in a low engine speed region, there is known a de- mon, there are a number of advantages of employing 15 vice in which the above first to third intake valve open- five valve per cylinder with three intake valves. The ex- ings are led outward and connected at their midways to cellent breathing capacity of a five valve engine is well a common intake passage and in which one fuel injec- acknowledged. However, because of the good breath- tion valve is provided in the common intake passage and ing capacity of five valve engines, these engines may an open-close valve which is opened only in a high en- have a tendency to have poor performance at low and 20 gine speed stage is provided in one of the intake pas- mid-range speeds. The reason for this is that the flow sages, as described in Japanese Published Unexam- velocity through the three intake passages under these ined Utility Model Application No. Sho-61 -186726. running conditions is extremely low and poor combus- Moreover, an intake device has been proposed in tion and fuel vaporization can result. It has been, there- which a first intake passage in fluid communication with fore, been proposed to provide some staging system so 25 one of the above intake valve openings and a second that the effective intake area of the engine is reduced intake passage in fluid communication with the other, when operating at low and mid-range speeds. two intake valve openings are provided and in which a Although such staging systems significantly im- carburetor is independently provided in each of the first prove the performance of the engine at low speeds, they and second intake passages so that the air-fuel mixture do give rise to some difficulties. For example, if the stag- 30 is fed through the first intake passage only in a low en- ing is accomplished by providing a throttle valve in each gine speed region but is fed through both of the first and intake passage, then the cylinder head porting configu- second intake passages in a middle or high engine ration and throttle valve arrangement can become com- speed region (see, for example, Japanese Patent Ap- plicated. If, on the other hand, two of the intake passag- plication No. Hei-1 -309466). es are siamesed and the third is left separate and a th rot- 35 In addition to the porting considerations previously tie valve is provided only the siamesed passage, it has described, the use of multiple intake valves, particularly been noted that mid-range performance can deterio- if staging is employed, can give rise to certain difficulties rate. That is, it has been found with such an arrange- in connection with the associated charge forming sys- ment that there may be a dip in the torque curve of the tem. Specifically, if fuel injection and specifically port fuel engine at mid-range. Since this is a commonly operated 40 injection is employed and a staged induction system is speed range for the engine, such an arrangement may also incorporated, then it is very difficult to utilize a single not be acceptable. fuel injector for spraying fuel into all of the intake pas- It has been discovered, however, that this problem sages. This can present some problems even if staging with mid-range performance can be overcome by pro- is not employed because it is difficult to position an in- viding at least some communication between the intake 45 jector and have its spray nozzle in such an orientation ports even though they are basically separated. How- to insure that a uniform mixture is supplied to the com- ever, this can present some problems in connection with bustion chamber under all running conditions. Alterna- the forming of the interconnecting passageway and tively, even if stratification is desired, the mixture alloca- keeping it close to the intake valve seats, where it is tion within the combustion chamber can be difficult. most effective so Therefore, the objective of the present invention to A multiple valve internal combustion engine of the provide a multiple valve internal combustion engine of type mentioned at the beginning is known from US-A-4 the defined on the preamble of claim 1, having an en- 627 400. In said prior art the interconnecting passage is hanced staged induction allowing improved swirl action arranged transversely to the intake passages, which of the intake charge specifically under mid range engine with respect to the direction of flow of the charge coming 55 running conditions in order to obtain an optimum per- from the carburettor causes fluid flowing though said in- formance of the engine under all running conditions. terconnecting passage to perform an overall 90° turn. According to the present invention the above objec- Moreover, in said known engine the inlet of said inter- tive is obtained by a multiple valve internal combustion 2 3 EP 0 499 268 B1 4 engine of the type defined in the preamble of claim 1 DETAILED DESCRIPTION OF THE PREFERRED wherein the interconnecting passage is disposed within EMBODIMENTS OF THE INVENTION the cylinder head extending adjacent to and towards a centre valve seat allowing the amount of the charge sup- Referring first to Figure 1 , a motorcycle powered by plied to said centre valve seat to be varied in response 5 an internal combustion engine constructed in accord- to the load conditions of the engine. ance with an embodiment of the invention is identified According to a preferred embodiment of the present generally by the reference numeral 21 . The invention is invention the cylinder head defines a combustion cham- described in conjunction with a motorcycle since it has ber and at least three intake valve seats therein and a particular utility in conjunction with such this type of ve- pair of separate inlet openings are formed, preferably in 10 hide. It is to be understood, however, that certain facets another surface of the cylinder head, and first and sec- of the invention may be utilized in conjunction with in- ond intake passages formed in the cylinder head extend ternal combustion engines that power other types of ve- from the respective one of said inlet openings to the hicles or, for that matter, other applications for internal valve seats wherein one side valve seat is served by the combustion engines. first intake passage while the other two valve seats, is The motorcycle 21 includes a welded frame assem- namely a center valve seat and another side valve seat bly 22 having a head pipe 23 that journals a front fork are served by the common Siamese type second intake 24 for steering movement. A front wheel (not shown) is passage. Moreover, the interconnection passage is pro- journaled by the front fork 24 in a known manner.