US3733794A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Safe starting system for lawn and garden equipment
Assignee: Deere and Co
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Filing: 1972-03-22
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Granted: 1973-05-22
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Expires: 1992-03-22
Abstract
Abstract A riding mower has an internal combustion engine with a magneto type ignition system. A mower is suspended from the tractor and driven from the engine through a belt drive, which includes a clutch, while the traction wheels are driven through a different drive system, which also includes a clutch. A pair of series connected switchs are respectively connected to the clutches, so that they are open when the clutches are engaged, and closed only when the clutches are disengaged. The ignition system generates a sine wave voltage in the primary winding, the positive voltage excursion being utilized to generate the high voltage spike in the secondary winding which fires the spark plug. However, the positive voltage excursion in the primary coil can be shorted to ground through a diode and a relay, when the relay is deenergized. The relay is energized when both the safety switches are closed during the negative voltage excursion, so that the primary winding short is interrupted and the engine can be started only when both the clutches are disengaged. After the relay is energized, it completes a circuit in parallel with the safety switches, so that the clutches may be engaged once the engine is started without shorting out the primary winding.
Inventors
- 👤 D Allen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 02:45
CPC Classifications
A; A01; A01D; A01D34/00; A01D34/01; A01D34/412; A01D34/63; A01D34/82; A01D34/828; A01D34/67; A01D34/68; A01D34/6806; A01D34/6818; Y; Y10; Y10S; Y10S56/00; Y10S56/15
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
302 words
In a combination tractor and mower having a mobile main frame, an internal combustion engine mounted on the frame and having a magnetO ignition system generating a sine wave voltage pattern with positive and negative voltage excursions in a primary winding producing a high voltage spike in a secondary winding during one voltage excursion, a traction drive for propelling the main frame and including a selectively engageable and disengageable clutch means, a mower carried by the main frame, and means drivingly connecting the engine to the mower and including a selectively engageable and disengageable clutch means, the improvement comprising: an electrical relay means shiftable from a normal position to a closed position when its coil is energized; a first diode operatively connected in series with the relay means and the primary winding to short the primary winding to ground during said one voltage excursion when the relay means is in its normal position; a first switch means operatively connected to and responsive to the condition of one of said clutch means so that it is open when the clutch means is engaged and closed when the clutch means is disengaged; a second diode operatively connected in series with the relay coil, the first switch means, and the primary coil for permitting a current flow through the switch means and the relay coil during the other voltage excursion when the switch means is closed to shift the relay to its closed position and thereby interrupt the short of the primary winding and permit starting of the engine only when said clutch means is disengaged; and means connecting the relay means in parallel with the switch means when the relay means is in its closed position to bypass the switch means and maintain the energization of the relay coil once the engine has started.
Claim 2
Dependent Claim
302 words
In a combination tractor and mower having a mobile main frame, an internal combustion engine mounted on the frame and having a magnetO ignition system generating a sine wave voltage pattern with positive and negative voltage excursions in a primary winding producing a high voltage spike in a secondary winding during one voltage excursion, a traction drive for propelling the main frame and including a selectively engageable and disengageable clutch means, a mower carried by the main frame, and means drivingly connecting the engine to the mower and including a selectively engageable and disengageable clutch means, the improvement comprising: an electrical relay means shiftable from a normal position to a closed position when its coil is energized; a first diode operatively connected in series with the relay means and the primary winding to short the primary winding to ground during said one voltage excursion when the relay means is in its normal position; a first switch means operatively connected to and responsive to the condition of one of said clutch means so that it is open when the clutch means is engaged and closed when the clutch means is disengaged; a second diode operatively connected in series with the relay coil, the first switch means, and the primary coil for permitting a current flow through the switch means and the relay coil during the other voltage excursion when the switch means is closed to shift the relay to its closed position and thereby interrupt the short of the primary winding and permit starting of the engine only when said clutch means is disengaged; and means connecting the relay means in parallel with the switch means when the relay means is in its closed position to bypass the switch means and maintain the energization of the relay coil once the engine has started.
Claim 3
Dependent Claim
85 words
The invention defined in claim 1 and including a second switch means connected in series with the first switch means, the second diode, and the relay coil, and shiftable between open and closed positions, respectively, in response to engagement or disengagement of the other clutch means to prevent initial energization of the relay coil and the starting of the engine when either clutch is engaged, the relay being connected in parallel with the serially connected switch means when the relay is in its closed position.
Claim 4
Dependent Claim
28 words
The invention defined in claim 1 wherein the first switch means is operatively connected to and responsive to the condition of the clutch means in the mower drive.
Claim 5
Dependent Claim
25 words
The invention defined in claim 1 and including a capacitor connected in parallel with the relay coil to provide relay coil current between voltage excursions.
Claim 6
Dependent Claim
39 words
The invention defined in claim 1 wherein the first diode is operative to permit current flow from the primary winding to ground only during the positive voltage excursion and the second diode conducts only during the negative voltage excursion.
Claim 7
Dependent Claim
290 words
In a lawn and garden machine having a mobile main frame, an internal combustion engine mounted on the frame and having a magneto ignition system generating a sine wave voltage pattern with positive and negative voltage excursion in a primary winding producing a high voltage spike in a secondary winding during one voltage excursion, at least one driven element, and means drivingly connecting the engine to said driven element and including a clutch means selectively engageable and disengageable to respectively establish or disestablish said driving connection, the improvement comprising: an electrical relay means shiftable from a normal position to a closed position when its coil is energized; a first diode operatively connected in series with the relay means and the primary winding to short the primary winding to ground during said one voltage excursion when the relay means is in its normal position; a first switch means operatively connected to and responsive to the condition of the clutch means so that it is open when the clutch means is engaged and closed when the clutch means is disengaged; a second diode operatively connected in series with the relay coil, the first switch means and the primary coil for permitting a current flow through the switch means and the relay coil during the other voltage excursion when the switch means is closed to shift the relay to its closed position and thereby interrupt the short of the primary winding, and permit starting of the engine only when the clutch means is disengaged; and means connecting the relay means in parallel with the switch means when the relay means is in its closed position to bypass the switch means and maintain the energization of the relay coil once the engine is started.
Claim 8
Dependent Claim
290 words
In a lawn and garden machine having a mobile main frame, an internal combustion engine mounted on the frame and having a magneto ignition system generating a sine wave voltage pattern with positive and negative voltage excursion in a primary winding producing a high voltage spike in a secondary winding during one voltage excursion, at least one driven element, and means drivingly connecting the engine to said driven element and including a clutch means selectively engageable and disengageable to respectively establish or disestablish said driving connection, the improvement comprising: an electrical relay means shiftable from a normal position to a closed position when its coil is energized; a first diode operatively connected in series with the relay means and the primary winding to short the primary winding to ground during said one voltage excursion when the relay means is in its normal position; a first switch means operatively connected to and responsive to the condition of the clutch means so that it is open when the clutch means is engaged and closed when the clutch means is disengaged; a second diode operatively connected in series with the relay coil, the first switch means and the primary coil for permitting a current flow through the switch means and the relay coil during the other voltage excursion when the switch means is closed to shift the relay to its closed position and thereby interrupt the short of the primary winding, and permit starting of the engine only when the clutch means is disengaged; and means connecting the relay means in parallel with the switch means when the relay means is in its closed position to bypass the switch means and maintain the energization of the relay coil once the engine is started.
Claim 9
Dependent Claim
17 words
The invention defined in claim 6 and including a capacitor connected in parallel with the relay coil.
Claim 10
Dependent Claim
106 words
The invention defined in claim 7 wherein the machine includes a second driven element connected to and driven by the engine through a second clutch means and including a second switch means connected in series with the first switch means, and the second diode, and the relay coil and shiftable between open and closed positions, respectively, in response to engagement or disengagement of the second clutch means to prevent initial energization of the relay coil and the starting of the engine when either clutch is engaged, the relay being connected in parallel with the serially connected switch means when the relay is in its closed position.
Claim 11
Dependent Claim
39 words
The invention defined in claim 6 wherein the first diode is operative to permit current flow from the primary winding to ground only, during the positive voltage excursion, and the second diode conducts only during the negative voltage excursion.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |