US 3358667 A
Description (OCR text may contain errors)
Dec. 19,1967 G BB ETAL 3,358,667
I STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Aug. 30, 1966 3 Sheets-Sheet 1 Dec. 19, 1967 GUBB ET AL 3,358,667
STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Aug. 50, 1966 3 Sheets-Sheet 2 Dec. 19, 1967 GU55 ET AL 3,358,667
STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Aug. 30, 1966 3 Sheets-Sheet 5 United States Patent 3,358,667 STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES Kenneth Frederick Gubh, Greenford, and Alec Harry Seilly, North Wembley, England, assignors to C.A.V. Limited, London, England, a British company Filed Aug. 30, 1966, Ser. No. 576,012 12 Claims. (Cl. 123-479) This invention relates to electric starting mechanism for internal combustion engines and has for its object to provide such mechanism in a simple and convenient form.
In the accompanying drawings:
FIGURE 1 is a sectional side elevation of one example of a mechanism in accordance with the invention.
FIGURE 2 is a view similar to FIGURE 1 but with portions removed to avoid repetition and showing the remaining parts in their alternative position.
FIGURE 3 is a section on the line 3-3 of FIG- URE 1.
FIGURE 4 is a view similar to FIGURE 1 showing another example of the mechanism with only the parts shown which differ from the mechanism of FIGURE 1.
Referring to the drawings there is provided a housing 10 which is secured to the casing 10a of an electric motor. Through the housing extends a shaft 11 which is connected to the armature 9 of the motor and which adjacent its free end is formed with a quick pitch screw thread. At the adjacent end of the shaft is secured an abutment in the form of a nut 12, and mounted on the shaft and in complementary screw thread engagement therewith is a pinion 13. Moreover, intermediate the pinion and the abutment is a coiled compression spring 14 acting as a pinion return spring. The pinion is secured to a sleeve 15 slidable upon the shaft, the sleeve being mounted for rotation within a bearing in the housing 10.
Also mounted within the housing is an annular solenoid 16 and this has associated therewith an armature 17 in the form of an annular member formed from magnetizable material. Furthermore, an armature return spring 18 is positioned intermediate a step on the internal periphery of the armature and the housing. In the internal periphery of the armature is formed a groove in which is accommodated a plurality of arcuate segments 20, and the segments are urged inwardly by a garter spring 21 which surrounds the segments and which is located within grooves formed therein. As shown in the drawings a step 22 is formed on the sleeve 15 and against which the segments 20 bear as the armature is moved upon energisation of the solenoid. Furthermore, the sleeve is provided with a portion 19 which tapers outwardly towards the motor away from the step 22.
Mounted on the armature is a tiltable plate 23 upon which are mounted a pair of electrical contacts 24, 25 and these can co-operate with fixed contacts 26, 27 respectively mounted on a plate 8 which retains the solenoid coil within the housing. The plate 23 is held in position on the armature by a coiled spring 28. Moreover, pivotally mounted within the housing is a spring loaded catch 29 which initially acts to restrain the movement of one point on the circumference of the plate 23 as will be described. The contacts are so aranged that when the contacts 24 and 26 are closed the motor will be energised so as to deliver only a portion of its power output and when the contacts 25, 27 are closed the full power output of the motor is obtained.
At one point on the shaft is formed a rounded step 30 and extending from this step towards the armature is a plain cylindrical portion 31 which is of enlarged diameter. The sleeve 15 at this point is formed with two 3,358,667 Patented Dec. 19, 1967 series of angularly spaced holes in which are located two series of balls 32, 33 respectively. The series of balls 32 are disposed nearer to the motor than the series of balls 33 and will be referred to as locking balls. Slidable upon the sleeve 15 is a collar 34 and the collar is urged in a direction towards the pinion by a coiled compression spring 35. The internal periphery of the collar is shaped to define an outwardly tapering shoulder followed by a straight portion and in the rest position as shown in FIG- URE 1 the locking balls 32 bear against the outwardly tapering shoulder.
The operation of the mechanism will now be described. Upon energisation of the solenoid by the operator the armature 17 moves towards the pinion and in so doing the segments 20 engage with the step 22 so that the sleeve 15 is also moved axially together with the pinion. After a small movement of the armature the contacts 24 and 26 will be closed and the shaft 11 and pinion will be rotated. When the armature 17 nears the end of its permitted movement the pinion will engage with a toothed wheel 13a of the engine and the action of the quick pitch thread will complete the engagement of the pinion with the toothed wheel. During this final movement of the sleeve, the catch 29 is tripped by a trip plate 36 mounted on the sleeve and contacts 25 and 27 are closed to allow the motor to develop its full power. Furthermore as the sleeve moves relative to the armature the tapered portion 19 of the sleeve urges the segments 20 outwardly and they are retained in this position by the magnetic flux produced by the solenoid. Thus, when the pinion 13 is engaged with the toothed Wheel 13a the armature 17 is no longer connected to the sleeve. As the sleeve 15 moves relative to the shaft 11 the balls 32 engage with the rounded step 30 formed on the shaft and the collar 34 is moved in a direction towards the pinion by the spring 35. As shown in FIGURE 2 the balls 32 bear against the plain portion of the collar 34 and the balls 33 bear against the tapered portion of the collar.
If when the engine starts the operator de-energises the solenoid then the armature first moves the collar 34 against the action of the spring 35 to permit the sleeve to move relative to the shaft, which movement is accomplished partly by the return spring 14 and partly by the action of the quick pitch thread.
If however the operator does not de-energise the solenoid the engine will drive the shaft and in view of the large gear reduction the shaft could attain a high speed of rotation which could damage parts connected thereto particularly the armature of the motor. In this event however once the shaft has reached a predetermined speed of rotation, the centrifugal force acting on the series of balls 33 will be sufiicient to move the collar against the action of its spring to release the locking balls 32 from the step 30 and when this occurs the combined action of the spring 14 and the quick pitch thread will be suificient to move the pinion out of engagement with the toothed wheel. It will be noted that the armature does not move and therefore the electrical contacts remain closed so that the motor will continue to rotate at its free running speed.
Another example of a mechanism in accordance with the invention is shown in FIGURE 4 and in this example parts which are identical with those shown in FIGURES 1, 2 and 3 are given the same reference numerals.
In this example the armature of the solenoid 16 is again of annular form but is split axially into a number of portions 40. These are held together in the manner of a collet by a band spring 41. The ends of the portions remote from the armature are shaped for co-operation with an annular inclined ramp 42 formed integrally with the housing 10 and the arrangement is such that when the armature has moved its fullest extent under the action of thesolenoid theportions 40' will be removed from engagement with the step 22 of the sleeve 15. To support the portions 40 at their ends adjacent the motor an annular ring 42' is provided which is engaged within grooves formed in the internal periphery of the portions 40.
Moreover, in this example the locking balls 32 when the pinion is properly engaged with the toothed wheel of the engine fall into recesses 43 respectively formed in the periphery of the shaft 11. The collar member 34 acts in a similar manner to retain the locking balls within the recesses and the spring 35 is provided to retain the collar in the locking position. In order to move the collar against the action of the spring 35 the balls 33 are located within a chamber defined by one face of a radial flange on the collar member 34 and an inwardly inclined face formed on a hollow member 44 surrounding the collar and secured to the sleeve. The. arrangement is such that when the collar is in the locked position the balls 33 are held at their innermost positions between the aforesaid faces by the action of the spring 35. If the operation maintains the solenoid energised after the engine has started then centrifugal force acting on the balls 33 will cause the collar to be moved against the action of its spring and the locking balls 32 will be urged out of their recesses and the pinion will be moved out of engagement with the toothed wheel by the action of the quick pitch thread and the return spring.
Having thus described our invention what we claim as new and desire to secure by Letters Patent is:
1. A starting mechanism for an internal combustion engine and comprising in combination a shaft which is arranged to be driven when it is required to start the engine, an axially moveable pinion in driving engagement with said shaft, a first member axially moveable relative to the shaft and arranged when moved in one direction to move the pinion axially into engagement with a toothed wheel of the engine, locking means operable to lock said first member to the shaft when the pinion is engaged with the toothed wheel, an operator controlled second member arranged when operated, to engage with the first mem-- her to cause the latter to move the pinion axially, said second member being so arranged that at the limit of its travel under the control of the operator it will be disengaged from the first member, centrifugallyoperablemeans arranged to release said locking means when the shaft attains a predetermined speed of rotation, and means for moving the pinion axially out of engagement with the toothed wheel.
2. A starting mechanism as claimed in claim 1 in which said centrifugally operable means comprises a plurality of balls which are acted upon by centrifugal force and which when the speed of rotation attains a predetermined value releases said locking means.
3. A starting mechanism as claimed in claim 2 in noid which is arranged to be energised when it is requiredv which the first member is in the form of a sleeve which surrounds the shaft and the second member is of annular form and surrounds the sleeve, said sleeve being provided with a step with which the second member or a part secured thereto co-operates to transmit movement of the second member by the sleeve.
4. A mechanism as claimed in claim 3 in which the second member is provided with a groove in its internal periphery in which are located a plurality of arcuate segmental pieces which are loaded into Contact with the sleeve by a garter spring.
5. A mechanism as claimed in claim 4 in which the completion of the engagement of the pinion with the toothed wheel is elfected by a quick pitch screw thread connection between the pinion and the shaft.
6. A mechanism as claimed in claim 5 in which the segmental pieces are moved outwardly beyond the step on the sleeve by an outwardly tapering portion of the sleeve.
7. A mechanism as claimed in claim 6 in which the segmental pieces are held outwardly by the action of a solenoid which is'arrangedto be energised when the starting mechanism is brought into operation.
8. A mechanism as claimed in claim 7 in which the second member constitutes the armature of the solenoid.
9. A mechanism as claimed in claim 3 in which the second member is divided axially so as to form the equivalent of a collet, a garter spring being provided to retain the portions of the member against the step on the sleeve.
10. A mechanism as claimed in claim 9 in which the portions of the second member are moved out of engagement with the step on the sleeve bythe interaction of the ends of the portions of the second member with a ramp.
11. A mechanism as claimed in claim 10 in which the portions of the second member are formed from magnetizable material and constitute the armature of a soleto bring the starting mechanism into operation.
12. A mechanism as claimed in claim 11 in which the completion of the engagement of the pinion with the toothed wheel is effected by a quick pitch screw thread connection betweeen the pinion and the shaft.
References Cited UNITED STATES PATENTS 1,501,497 7/1924 Schwarz 123-185 2,455,328 11/1948 Buxton 290-38 2,727,158 12/ 1955 Seilly 290-38 2,727,998 12/195-5 Buxton 290-38 3,124,694 3/ 1964 Seilly 290-38- 3,177,368 4/1965 Seilly 290-38 3,210,554 10/1965, Seilly et al 290-38 WENDELL E. BURNS, Primary Examiner,