Power Storage Type Recoil Starter

Europaisches Patentamt 19 European Patent Office

Office europeen des brevets © Publication number : 0 623 743 A1

EUROPEAN PATENT APPLICATION

(22) Date of filing : 06.05.94

@ Date of publication of application : @ Representative : Irons, Mark David et al 09.11.94 Bulletin 94/45 Page White & Farrer, 54 Doughty Street _ London WC1N 2LS (GB) (84) Designated Contracting States : DE FR GB IT

© A power storage type recoil starter used for, for example, an engine of a lawn mower includ- ing spiral springs that are wound when a starter 56 55 rope of a recoil pulley is pulled to rotate the starter wheel of the engine. The spiral spring is coiled up by a repeated pulling action of the starter rope and then suddenly recoiled by releasing a locking mechanism, thus rotating the main shaft of the engine powerfully to start the engine.

CO co CM CO

LU Jouve, 18, rue Saint-Denis, 75001 PARIS 1 EP 0 623 743 A1 2

BACKGROUND OF THE INVENTION holders by the rotation of the second drum in a direction opposite to the starting direction so that the re- 1. Field of the Invention winding force of the spring is stored in the second drum as a rotational force in the starting direction, a The present invention relates to a power storage 5 locking mechanism which restrains the rotation of the type recoil starter for facilitating the start of internal second drum in the starting direction, and a release combustion engines. mechanism which releases the locking mechanism and disengages the clutch mechanism simultaneous- 2. Prior Art ly- 10 The object of the present invention is accomplish- Small internal combustion engines are equipped ed by another unique structure for a recoil starter with a recoil starter, and the starting of the engine is structure wherein a starter wheel which is attached to accomplished by pulling a starter rope that is recoiled. the main shaft of an engine and a recoil pulley which In such recoil starters, a certain amount of exper- rotates the starter wheel in the starting direction are ience is necessary to start the engine. The trick is to 15 installed separately, and between these two ele- pull the starter rope strongly at the time the air in the ments are provided: a first drum which is rotated by cylinder of the engine is compressed immediately pri- the recoil pulley in the opposite direction from the or to the firing of the plug. However, this operation is starting direction, a rotatable second drum, a speed not skillfully performed by inexperienced persons reduction mechanism which is installed between the and people who have limited strength. These people 20 recoil pulley and the first drum, a one-way clutch tend to pull the starter rope with an uneven strength mechanism which allows the rotation of the first drum and at a relatively slow speed. The result is that the in the starting direction and restrains the rotation of spark of the plug is small, and ignition does not easily the first drum in the direction opposite to the starting occur. Especially in recent engines equipped with direction, a flat spiral spring which is installed be- electronic ignition devices, the spark is small, and 25 tween the first and second drums so as to be wound starting is not easy. by the rotation of the first drum in the starting direc- The problem can be solved by an engine equip- tion so that the rewinding force of the spring is stored ped with a starter motor. However, this motor is ex- in the second drum as a rotational force in the starting pensive and increases the weight of the engine. Es- direction, a locking mechanism which restrains the ro- pecially for garden equipment which is carried and op- 30 tation of the second drum in the starting direction, and erated with the engine mounted thereon, such a a release mechanism which releases the locking weight increase is not welcome. In addition, there are mechanism. also problems in terms of power consumption. The object of the present invention is accomplished by still another structure for a recoil starterwhere- SUMMARY OF THE INVENTION 35 in a starter wheel which is attached to the main shaft of an engine and a recoil pulley which rotates the star- Accordingly, it is a primary object of the present ter wheel in the starting direction are installed sepa- invention to solve the problems described above. rately, and between these two elements are provided More specifically, in the present invention, power is with: a first drum which is rotated by the recoil pulley stored in a recoil starter via flat spiral springs, and at 40 in the opposite direction from the starting direction, a the time of starting, the stored power is released all rotatable second drum, a speed reduction mecha- at once so that the starter is rotated at a high speed nism which is installed between the recoil pulley and to start the engine. the first drum, a one-way clutch mechanism which al- In order to accomplish the object, the recoil star- lows the rotation of the first drum in the starting direc- ter of the present invention uses a unique structure ts tion and restrains the rotation of the first drum in the wherein a starter wheel which is attached to the main direction opposite to the starting direction, and a flat shaft of an engine and a recoil pulley which rotates spiral spring which is installed between the first and the starter wheel in a starting direction are installed second drums so as to be wound by the rotation of the separately, and between these two elements is pro- first drum in the starting direction so that the rewind- vided: a first drum which is rotated by the recoil pulley so ing force of the spring is stored in the second drum as in the direction opposite from the starting direction, a a rotational force in the starting direction. second drum which is coupled to the first drum so as With any one of the above structures of the pres- to be rotated, a speed reduction mechanism which is ent invention, even if the recoil pulley is driven at a installed between the recoil pulley and the first drum, slow speed and in a small amount via a starter rope, a clutch mechanism which makes and releases a cou- 55 repetition of this driving for several times can cause pling between the first and second drums, flat spiral a starting force to be stored by the flat spiral spring. springs which are installed between the second drum Accordingly, an increased high-speed rotational force and spring holders so as to be wound out of the spring can be applied to the starter wheel by the spiral 2 3 EP 0 623 743 A1 4 spring, so that the engine can be started without any driving wheel 24 and rotates the driving wheel 24. failure, and energy saving is also accomplished. A first drum 26 and a second drum 36 are installed between the recoil pulley 16 and the starter wheel BRIEF DESCRIPTION OF THE DRAWINGS 14. 5 The first drum 26 is rotated by the recoil pulley 16 Figure 1 is a longitudinal cross sectional view of in the opposite direction (called the "anti-starting di- the power storage type recoil starter of the pres- rection") which is opposite from the starting direction ent application; of the starter wheel 14 (called the "starting direction"). Figure 2 is a perspective view thereof; The second drum 36 is rotated by the first drum 26 via Figure 3 is a right-side view of the starter wheel 10 a clutch mechanism 28 which is installed between the of the recoil starter of Figure 1 ; first drum 26 and the second drum 36. Figure 4 is a right-side cross sectional view of the When the second drum 36 is rotated, it winds out second drum and two spring holders along with flat spiral springs 32 installed between the second flat spiral springs used in the starter of Figure 1 ; drum 36 and spring holders 30 as seen in Figure 4 so Figure 5 is a right-side cross sectional view of the 15 that the rewinding force of the springs 32 is stored as ratchet used in the starter of Figure 1 ; a rotational force in the starting direction when the ro- Figure 6 is a longitudinal cross sectional view of tation of the second drum 36 in the starting direction another type of the power storage type recoil (shown by arrow B in Figure 3) is restrained by a lock- starter of the present invention; ing mechanism 34. Figure 7 is a right-side view of the one-way clutch 20 More specifically, a drive shaft 38 of the driving used in the starter of Figure 6; wheel 24 is inserted as an input shaft into a planetary Figure 8 is a right-side cross sectional view of the type speed reduction mechanism 40. The outer cir- ratchet used in the starter of Figure 6; cumference of this speed reduction mechanism 40 is Figure 9 is a right-side cross sectional view of the formed as a rotation outputting member. The direc- second drum and first drum along with a flat spi- 25 tion of rotation of this outputting member is opposite ral spring used in the starter of Figure 6; to the rotational direction of an rotation inputting Figure 1 0 is a left-side cross sectional view of the member of the reduction mechanism 40 which is con- rotating block of the second drum used in the nected to the drive shaft 38. starter of Figure 6; and The first drum 26 is fitted over the thus designed Figure 11 is a longitudinal cross sectional view of 30 outputting member of the speed reduction mecha- the still another type of power storage type recoi I nism 40 so as to be free to slide in an axial direction. starter of the present invention. As a result, the rotational force of the recoil pulley 16 is transmitted to the first drum 26 with the speed re- DETAILED DESCRIPTION OF THE INVENTION duced by approximately 1/5 by the speed reduction 35 mechanism 40 and with the direction of rotation of the As seen from Figure 1, in the power storage type drive shaft 38 reversed. The second drum 36 is fitted recoil starter of the present invention, a starter wheel loosely over the outer circumference of the first drum 14 which is attached to the main shaft 12 of an engine 26, and a clutch mechanism 28, in which claws 28a 10 and a recoil pulley 16 which rotationally drives the and 28b (see Figure 2) are engaged with each other, starter wheel 14 are separately installed from each 40 is installed between the facing end surfaces of the other; and the recoil starter is provided between two drums. The claws 28b is provided on the end sur- these two elements. face of the first drum 26, and the claws 28a is provid- Figure 3 shows the right-side of the recoil pulley ed on the end surface of the second drum 36. 16. The recoil pulley 16 is a rotatable member having The clutch mechanism 28 functions upon the slid- therein a known recoil mechanism, and a starter rope 45 ing motion of the first drum 26. In particular, when the 18 is wound around the outside circumference of the first drum 26 slides in the direction which causes it to pulley 16. A rotating block 20 is provided so as to pro- move out of the second drum 36 (in other words to the ject from the inside surface of the pulley 16 as seen right in Figure 1 ), the engaging claws 28a and 28b are in Figure 1. separated; and when the first drum 26 slides in the di- A driving wheel 24 is installed next to the recoil 50 rection which causes it to move into the second drum pulley 16. The driving wheel 24 is the same in struc- 36 (in other words to the left in Figure 1), the claws ture as the starter wheel 14 and is rotated via a dog 28a and 28b are engaged. 22 when the recoil pulley 16 is rotated in one direc- The above described sliding motion of the first tion. More specifically, the recoil pulley 16 is rotated drum 26 is accomplished by moving or pushing a wire alone in the counterclockwise or recoil direction that 55 spring 42 that is provided in an erected posture at the is shown by arrow A in Figure 3 but when the pulley neck of the first drum 26 (Figure 2). The wire spring 16 is rotated via the starter rope 18 clockwise as 42 is pushed by a release mechanism 55 which as will shown by arrow B, the pulley 16 engages with the be described below releases a locking mechanism 3 5 EP 0 623 743 A1 6

34. In other words, when the release mechanism 55 and clutch mechanism 28. is actuated so as to release the locking mechanism In operation, the starter rope 18 is pulled so that 34, the wire spring 42 is moved or pushed to the right the recoil pulley 16 is rotated clockwise or in the start- in Figure 1 , separating the engaged claws 28a and ing direction. The starter rope 18 is coiled back on the 28b. The first drum 26 is designed so as to be kept 5 recoil pulley 16 by the recoil mechanism of the recoil urged in the direction (to the left in Figure 1) which pulley. As a result, the driving wheel 24 is rotated makes it engage with the clutch mechanism 28 by a clockwise, and this rotational force is transmitted to spring 44 which is installed between the first drum 26 the first drum 26 with the speed reduced and the ro- and the speed reduction mechanism 40. tational direction reversed to counterclockwise by the The spring holders 30, which are respectively in 10 planetary type speed reduction mechanism 40. The a drum shape and mounted to the frame of the starter, clutch mechanism 28, as a result, causes the second are provided on both sides of the second drum 36 so drum 36 to rotate by the same amount and in the that the axes of the holders 30 and the second drum same direction, causing the flat spiral springs 32 to be 36 are parallel. To the outer circumference of the sec- wound out of the spring holders 30 and wound around ond drum 36, one end of each one of the flat spiral 15 the second drum 36. springs 32 held in the spring holders is secured. An- When a prescribed amount of each of the flat spi- other end of each spring 32 is secured to each one of ral springs 32 is wound around the second drum 36 the drum shaped spring holders 30. Figure 4 shows and power is stored, the second drum 36 is urged to the installation of the flat spiral springs 32. rotate in the clockwise direction by the rewinding The spiral springs 32 are a shape-memory type 20 force of the springs 32. However, this rotation is re- spring; and when the springs 32 are wound out of the strained by the locking mechanism 34. spring holders 30 and wound on the second drum 36, When the second drum 36 is rotated by a prescri- a rewinding force that corresponds to the amount of bed amount and the rewinding force of the flat spiral deformation of the springs 32 is generated, so that springs 32 has become sufficiently strong, the re- this force is stored in the second drum 36 as a rota- 25 lease mechanism 55 is actuated so that the locking tional force in the starting direction. mechanism 34 is released and the clutch mechanism In the structure shown in Figure 4, two spring 28 is disengaged. As a result, the rewinding force of holders 30 are used so that they are provided on both the flat spiral springs 32 causes the second drum 36 sides of the second drum 36. However, only one alone to rotate clockwise. The rotating block 46 instal- spring holder 30 can be used along with only one 30 led on the second drum 36 acts on a dog 22 provided spring 32 as long as an appropriate rewinding force on the starter wheel 14, thus causing the main shaft can be generated by one spring. 12 to rotate via the starter wheel 14 in the starting di- A locking mechanism 34 which restrains the ro- rection so that the engine 10 is started. tation of the second drum 36 in the starting direction Figure 6 shows another type of power storage is installed on the second drum 36. Figure 5 shows 35 type recoil starter of the present invention. In this the locking mechanism 34. As seen from Figure 5 and structure, the first and second drums 26 and 36 are also from Figure 1 , a ratchet wheel 48 is provided on provided so as to overlap one inside the other, and a the second drum 36, and rotating block 46 which acts flat spiral spring 32 is installed between these two in the same way as the rotating block 20 of the recoil drums 26 and 36 so that the second drum 36 is rotat- pulley 16 does is mounted on this ratchet wheel 48. A 40 ed by the rewinding force of the spring 32. locking arm 52 is installed so as to pivot about a pin More specifically, the output shaft 58 of the 50. The locking arm 52 engages with the ratchet speed reduction mechanism 40 is long enough so that wheel 48 so that rotation of the ratchet wheel 48 in the the first drum 26 and the second drum 36 are fitted starting direction is restrained. on this output shaft 58. The first drum 26 has a small Near the locking arm 52, a release mechanism 55 45 diameter portion so as to be fitted on the output shaft is provided. The release mechanism 50 for releasing 58 and is located inside the second drum 36. The flat the locking mechanism 34 includes a lever 56 which spiral spring 32 is installed between the thus ar- pivots about a pin 54. When this lever 56 is pushed ranged first drum 26 and second drum 36 which has down, it acts on the locking arm 52, and the locking a larger diameter than the first drum 26. arm 52 is disengaged from the ratchet wheel 48. As 50 In this structure, in order to store the rotational seen from Figure 1 , the lever 56 is shaped so as to power of the flat spiral spring 32 via the recoil pulley be in touch not only with the locking 52 but also with 16 so that a clockwise rotational force is imparted to the wire spring 42. Thus, when the lever 56 is pushed the second drum 36, it is necessary to rotate the first down, the wire spring 42 is pushed to the right in Fig- drum 26 clockwise and to prevent the first drum 26 ure 1 , causing the first drum 26 to be slide to the right 55 from being rotated counterclockwise when the recoil to disengage the clutch mechanism 28. pulley 16 is coiled back. In order to satisfy this, a one- As seen from the above, the operation of release way clutch mechanism 60 is used so that it prevents mechanism 55 affects both locking mechanism 34 the counterclockwise rotation of the first drum 26. 4 7 EP 0 623 743 A1 8

Figure 7 shows a part of the right-side of the one- projection 68, thus preventing the breakage. When way clutch mechanism 60. The clutch mechanism 60 the first drum 26 is rotated clockwise in Figure 9, the is a ratchet type and includes a ratchet wheel 62 pro- anchoring projection 68 enters the anchoring hole 70, vided on the first drum 26 and a locking lever 64 which so that the spiral spring 32 is wound over the first is pivotally attached to the frame of the starter. 5 drum 26. Figure 8 shows the right-side of the locking mech- Breakage may occur to the rotating block 46 anism 34 that prevents the rotation of the second which drives the starter wheel 14 of the engine 10. In drum 36 in the clockwise direction. In this structure, particular, when the rotating block 46 is driven by the the release mechanism 57 which releases the locking rewinding force of the flat spiral spring 32, the starter arm 52 for preventing the rotation of the second drum 10 wheel 14 may be broken by the resulting shock if the 36 in the clockwise direction is provided with a knob rotating block 46 and the dog 22 of the starter wheel 66. 14 are too far apart. In severe cases, the crankshaft Thus, when the recoil pulley 16 is rotated several of the engine 10 may bend. times clockwise which is the same as the starting di- Figure 1 0 shows the left-side of the rotating block rection so that a rewinding force is stored in the flat 15 46 provided with a breakage preventive means. The spiral spring 32, the release mechanism 57 is operat- rotating block 46 is provided so that it is capable of ed. This operation causes the second drum 36 to ro- making a certain degree of relative rotation with re- tate clockwise by the force of the spring 32. As a respect to the second drum 36, and a shock-absorbing sult, the starter wheel 14 is rotated by the rotating material 72 such as rubber, etc. is attached to the con- block 46 installed on the second drum 36, rotating the 20 tact areas (or load contact areas) of the rotating block main shaft 12 of the engine 10. 46 and the second drum 36, thus alleviating shocks. The feature of this structure is that the first drum The shock-absorbing material 72 may be installed on 26 and second drum 36 are rotated in the same direc- both the load side and the opposite side as shown in tion when power is stored in the flat spiral spring 32. Figure 10. Thus, the one-way clutch mechanism 60, which does 25 Figure 11 shows still another type of power stor- not require a disengaging operation as the clutch age type recoil starter of the present invention. This mechanism 28 in the structure of Figure 1 does, is starter is the same as the starter shown in Figure 6 sufficient. In addition, since the flat spiral spring 32 is except that the locking mechanism 34 and release wound concentrically between the first drum 26 and mechanism 57 are not used. In this structure, the the second drum 36, the overall size of the starter can 30 clockwise rotational force of the second drum 36 be smaller. caused by the power of the flat spiral spring 32 is not In the above structure, however, the flat spiral restricted but is constantly applied to the starter springs 32 might cause problems. In particular, the ro- wheel 14 as a load. tational force that occurs when the locking mecha- Before the engine enters the compression stroke, nism 34 is released might cause a large shock to the 35 a considerable resistance is generated and applied area where the spring 32 and first drum 26 are instal- onto the starter wheel 14 via the main shaft 12. Ac- led. As a result, breakage may occur at this area. cordingly, if the stored force of the flat spiral spring 32 Figure 9 shows the right-side of a means that can overcomes this resistance, the starter wheel 14 can prevent this breakage. The preventative means in- be rotated in the starting direction. cludes an anchoring projection 68 formed on the outer 40 In this structure as well, the starter wheel 14 be- circumference of the first drum 26 and an anchoring gins to rotate only after the recoil pulley 16 has been hole 70 formed at the inside end of the flat spiral driven several times. Accordingly, the force for rotat- spring 32, so that the flat spiral spring 32 is secured ing the starter wheel 14 is greatly largerthan the force to the first drum 26 by bringing the anchoring projec- obtained by directly rotating the recoil pulley 16 via tion into the anchoring hole 70. The anchoring projec- 45 the starter rope 18. Thus, reliable starting can be se- tion 68 is a peak-shape. It engages with the anchoring cured. hole 70 when the first drum 26 rotates in the direction The structure in Figure 11 is simple. In addition, that tightens the flat spiral spring 32 and disengages since the starting is performed with the rotating block from the anchoring hole 70 when the first drum 26 ro- 46 of the second drum 36 being in contact with the tates in the direction that relaxes the spiral spring 32. 50 dog 20 of the starter wheel 14, almost no shock will In particular, the slope of the front surface (right- occur. side surface in Figure 9) of the projection 68 is abrupt, In the embodiments described above, the recoil while the slope of the back surface (left-side surface pulley 16 and driving wheel 24 are installed in a casing in Figure 9) is gradual. As a result, the second drum 74 and mounted to the engine 10 via bolts 76 at a 36 can rotate abruptly clockwise in Figure 9, and 55 fixed distance from the starter wheel 14 using when this rotational force reaches the inside end of spacers 78. The rotatable members in the embodi- the spiral spring 32, the resulting inertia causes the ments such as the first drum 26, the second drum 36, anchoring hole 70 to disengage from the anchoring etc. are also provided in a rotatable manner by sup- 5 g EP 0 623 743 A1 10 porting plates 80 and other supporting members rection; which are installed at prescribed positions by the a second drum which is coupled to said bolts 76 and spacers 78. first drum so as to be rotated; As seen from the above, according to the present a speed reduction mechanism which is in- invention, power is stored as a strong force via the flat 5 stalled between said recoil pulley and said first spiral springs even if the starting operation is slow drum; and done weakly. Furthermore, the starter wheel and a one-way clutch mechanism which allows the recoil pulley which are installed with a space in be- a rotation of said first drum in said starting direc- tween can be used without any modification in struc- tion and restrains a rotation of said first drum in ture. It is only necessary to install the recoil starter in 10 a direction opposite to said starting direction; such a space. Accordingly, assembly is easy, and ex- a flat spiral spring which is installed be- isting recoil starters can easily be modified. tween said first drum and said second drum, said flat spiral spring being wound by a rotation of said first drum in a direction of said starting direction Claims 15 so that a rewinding force of said spring is stored in said second drum as a rotational force in said 1. A power storage type recoil starter comprising a starting direction; starter wheel attached to a main shaft of an en- a locking mechanism which restrains a ro- gine and a recoil pulley spacedly provided from tation of said second drum in said starting direc- said starter wheel so as to rotate said starter 20 tion; and wheel in a starting direction, and further compris- a release mechanism which releases said ing, between said starter wheel and said recoil locking mechanism and disengages said clutch pulley: mechanism simultaneously. a first drum which is rotated by said recoil pulley in a direction opposite from said starting di- 25 3. A power storage type recoil starter comprising a rection,; starter wheel which is attached to a main shaft of a second drum which is coupled to said an engine and a recoil pulley which is spacedly first drum so as to be rotated; provided from said starter wheel so as to rotate a speed reduction mechanism which is in- said starter wheel in a starting direction, and fur- stalled between said recoil pulley and said first 30 ther comprising, between said starter wheel and drum; said recoil pulley: a clutch mechanism which makes and re- a first drum which is rotated by said recoil leases a coupling between said first drum and pulley in a direction opposite from said starting di- said second drum; rection; a spiral spring which is installed between 35 a second drum which is coupled to said said second drum and an outside element, said first drum so as to be rotated; flat spiral spring being wound out of said outside a speed reduction mechanism which is in- element by a rotation of said second drum in a di- stalled between said recoil pulley and said first rection opposite to said starting direction so that drum; a rewinding force of said spring is stored in said 40 a one-way clutch mechanism which allows second drum as a rotational force in said starting a rotation of said first drum in said starting direc- direction; tion and restrains a rotation of said first drum in a locking mechanism which restrains a ro- a direction opposite to said starting direction; and tation of said second drum in said starting direc- a flat spiral spring which is installed be- tion; and 45 tween said first drum and said second drum, said a release mechanism which releases said flat spiral spring being wound by a rotation of said locking mechanism and disengages said clutch first drum in a direction of said starting direction mechanism simultaneously. so that a rewinding force of said spring is stored in said second drum as a rotational force in said 2. A power storage type recoil starter comprising a so starting direction. starter wheel which is attached to a main shaft of an engine and a recoil pulley which is spacedly 4. A power storage type recoil starter according to provided from said starter wheel so as to rotate Claim 1 , 2 or 3, further comprising: a rotating said starter wheel in a starting direction, and fur- block which is provided on said second drum so ther comprising, between said starter wheel and 55 as to rotates said starter wheel, said rotating said recoil pulley: block being provided in a manner of making a rel- a first drum which is rotated by said recoil ative rotation for a prescribed angle with respect pulley in a direction opposite from said starting di- to said second drum; and shock-absorbing mem- 6 11 EP 0 623 743 A1 12 bers which are interposed in contact areas between said second drum and said rotating block.

A power storage type recoil starter according to Claim 2 or 3, wherein said first drum is provided 5 with an anchoring projection on an outside circumference of said first drum, and said flat spiral spring is provided with an anchoring hole at one end of said spiral spring so that said spiral spring is connected to said first drum via said anchoring 10 projection engaged with said anchoring hole, said anchoring projection being formed in a peak- shape so that said peak-shape anchoring projection engages with said anchoring hole when said first drum is rotated in a direction that tightens 15 said flat spiral spring and so that said peak- shaped anchoring projection is disengaged from said anchoring hole when said first drum is rotated in a direction that relaxes said flat spiral spring. 20

A power storage type recoil starter according to Claim 4, wherein said first drum is provided with an anchoring projection on an outside circumference of said first drum, and said flat spiral spring 25 is provided with an anchoring hole at one end of said spiral spring so that said spiral spring is connected to said first drum via said anchoring projection engaged with said anchoring hole, said anchoring projection being formed in a peak- 30 shape so that said peak-shape anchoring projection engages with said anchoring hole when said first drum is rotated in a direction that tightens said flat spiral spring and so that said peak- shaped anchoring projection is disengaged from 35 said anchoring hole when said first drum is rotated in a direction that relaxes said flat spiral spring.

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FIG. 6

57 66

10 J ^36 f f 60

res :

12 KM

76 78

12 EP 0 623 743 A1

FIG. 7

FIG. 8

13 EP 0 623 743 A1

FIG. 9

FIG. 10

14 EP 0 623 743 A1

FIG. 11

76 78

15 EP 0 623 743 A1

buropcan Patent Application Number 9 EUROPEAN SEARCH REPORT Office EP 94 30 3283

DOCUMENTS CONSIDERED TO BE RELEVANT Category Citation oi document with indication, where appropriate, Relevant CLASSIFICATION OF THE of relevant passages to claim APPLICATION (Int.CI.5) US-A-3 140 703 (BARR) 1-3 F02N5/02 * column 3, line 32 - line 60; figures 1-7 F02N3/02

US-A-3 306 277 (GUDMUNDSEN) 1-3 * column 3, line 30 - line 52; figures 1-4

A US-A-3 861 374 (D00LEY)

A US-A-3 216 528 (L0HR)

TECHNICAL FIELDS SEARCHED (lnt.CI.5) F02N

The present search report has been drawn up for all claims riace oi searcn Dale of completion of the search Exaniaer THE HAGUE 12 August 1994 Bijn, E LA1M.URY Vt CUED DOCUMENTS T : theory or principle underlying the invention E : earlier patent document, but published on, or X : particularly relevant if taken alone after the filing date Y : particularly relevant if combined with another D : document cited in the application document of the same category L : document cited for other reasons A : technological background O : non-written disclosure & : member of the same patent family, corresponding P : intermediate document document