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5th Generation Fuel Injection System for Motorcycles

＊１ Development Department 1, R&D Operations　　＊２ Development Department 2, R&D Operations　　

＊３ Development Department 5, R&D Operations　　＊４ Development Department 3, R&D Operations　　

＊５ Production Engineering Department 3, Production Operations　　

※ Received 21 July 2014

Shinichiro MORITA＊１ Hiroki NOZAWA＊２ Yoshiaki NAKANOSE＊３

森　田　紳一郎 野　澤　広　樹 中ノ瀬　芳　昭 Tomoaki TAKAI＊４ Masaaki MITOBE＊１ Hiroshi YOSHIDA＊５

高　井　智　章 三戸部　雅　昭 吉　田　　　裕

新興国の小型二輪車市場において，燃費向上のニーズや排ガス規制への対応を背景として，キャブレタから燃料噴射システムへの移行が進んでいる．ここでは，第５世代の燃料噴射システムを構成するスロットルボデー・インジェクタ・フューエルポンプ・エンジン制御ユニットの概要を紹介する．

5th Generation Fuel Injection System for Motorcycles※

二輪車向け第５世代燃料噴射システム

1. Introduction

On markets of emerging countries, the carburetor

mounted on motorcycles with small-displacement

engine is superseded by the fuel injection system in

the context of the demand on improvement in fuel

efficiency and/or the conformity to more stringent

emission standards. In this report, components of

5th generation fuel injection system are outlined

respectively.

2. Throttle Body

The developed throttle body has a lineup widely

to maintain the compatibility with previous models.

Among this lineup, a high-performance model

particularly adopts the ISC (Idle Speed Control)

system and the integrated sensor which consists of

a throttle angle sensor, a intake pressure sensor and

a intake temperature sensor. The size of the throttle

body, however, remains in a slight increase because

attachment of the ISC component is devised and the

integrated sensor is downsized.

Technical Digest

3. Fuel Pump Module

The developed fuel pump module adopts a

pressure regulator with the press-fit structure and

a detection function of the suction filter clogging.

In order to achieve this function, the strainer is

designed such that it is possible to emit fuel vapor

and prevent the fuel back-flow. Especially, this

structure decrease the pump discharge rate by air

introduction when if the suction filter clogged up

with the dust intrusion in the fuel. The timing to

replace the suction filter is therefore informed via a

change in drivability.

Fig. 1 Throttle body (high-performance model)

81ISC type

Integrated sensor

ISC component

40.5

62.65

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Keihin Technical Review Vol.3 (2014)

Vapor outlet

Suction filter

BALL

GUIDE SPG

Press-FitStructure

SEAL BODY(SUS)

BODY(PPS)

(1)

(2)

(1) Pressure regulator

At vapor emission

Tank fuel high Tank fuel lowSTRAINER

MESH

FUEL AIR

At filter clogging

(2) Detection function of suction filter clogging

Fig. 2 Newly developed fuel pump module

22% in weight, and could be mounted flexibly into

more limited space of motorcycles.

5. Engine Control Unit

The developed engine control unit adopts the small

sized microcontroller with a built-in data flash memory.

Furthermore, a control method is devised so that

the secured data reliability is equivalent to the data

recording of the conventional method. The requested

rewrite count is therefore met even though the external

memory is removed. The failure detection circuit is

also unnecessary since the ASIC (Application Specific

Integrated Circuit) including a diagnostic detection

function is adopted. As a result, the size could be

reduced to 11% without any decrease in functionality.

Sleeve

Housing Housing

38.2mm18g

Fig. 3 Newly developed injector (KN7S)

45mm51mm

CPU(with a built-in data flash memory)

ASIC(including a diagnostic detection function)

Fig. 4 Newly developed engine control unit

4. Injector

The KN7S, developed injector is designed so

as the size and the weight are further less than the

KN7, miniature injector. For example, the sleeve of

the KN7 has a groove for an O-ring and a rib to

support a bobbin, but that of the KN7S is designed

simplified shape. As another example, although the

housing of the KN7 is a complex part with the deep

drawing shape, that of the KN7S is a symmetrical

shape axially and is split in axial. Finally, the

developed injector is reduced to 13% in size and

I feel great joy at reaching completion of the

successful new technology, thus reducing costs for

cooperating motorcycle manufacturers. Eventually we

will be able to supply motorcycles to new users on a

widespread basis. I greatly acknowledge the support of

this development by all persons concerned. (MORITA)

Author

Shinichiro MORITA