Safety interlock for machine and engine with magneto ignition

• US 4,294,327 A
• Filed: 12/15/1978
• Issued: 10/13/1981
• Est. Priority Date: 12/15/1978
• Status: Expired due to Term

• Current Assignee: Delta Systems Inc.
• Original Assignee: Delta Systems Inc.
• Inventors: Howard, William A.
• Primary Examiner(s): Peters, Jr., Joseph F.
• Assistant Examiner(s): Underwood, O. W.
• Application Number:
  US05/969,871
• Time in Patent Office: 1,033 Days
• Field of Search: 180/271, 180/272, 180/273, 180/287, 180/290, 123/198 DC, 307/105 B, 56/10.5
• US Class Current: 180/273
• CPC Class Codes: B60K 28/00 Safety devices for propulsion-unit control, specially adapted for, or arranged in, vehicles, e.g. preventing fuel supply or ignition in the event of potentially dangerous conditions for electrically-propelled vehicles B60L3/00; road vehicle drive control systems for purposes not related to the control of a particular sub-unit B60W30/00; drive control systems specially adapted for autonomous road vehicles B60W60/00
• CPC Class Codes: B60K 28/04 responsive to presence or absence of the driver, e.g. to weight or lack thereof

Abstract

A safety interlock for a vehicle driven through a transmission by an internal combustion engine that has a magneto ignition system and a seat occupied by a driver. The interlock is electrically connected to the ignition and to safety switches, one that is opened when the transmission to a traction drive is engaged and another that is closed when the seat is occupied. The interlock circuit disables the ignition if the engine is not running and the transmission is engaged so the engine cannot be started under unsafe conditions. The engine is also disabled if, after it is running, the seat becomes unoccupied while the transmission is engaged. However, the interlock allows the engine to be started with the seat occupied or not, as long as the transmission is disengaged. One or more safety switches associated with mechanisms driven by the engine can be connected in series with the transmission-operated safety switch to control operation in the same manner.

Claims

1. In a vehicle driven through a transmission to a traction drive by an internal combustion engine that has a magneto ignition system and that has a seat occupied by a driver, a seat-operated switch that is closed when the seat is occupied and a transmission-operated switch that is open when the transmission is engaged, an electrical circuit connected between said swtiches and across a primary winding of the magneto ignition, said circuit including means for selectively shorting the primary winding when the engine is not running and the transmission-operated switch is open, and means for shorting the primary winding when the engine is running and both the seat-operated switch and the transmission-operated switch are open.

2. In a machine driven by an internal combustion engine that has a magneto ignition system and having at least two switches, each separately operable, a first switch indicative when open of power transmission from the engine to a movable part of the machine and a second indicative when closed of operator-presence at controls of the machine, a safety interlock comprising:

a first control selectively operable to disable the ignition to prevent start of the engine, dependent upon the condition of the first swtich and independent of the condition of the second switch;

a second control selectively operable to disable the ignition to prevent engine running after start, dependent upon the condition of both the first and second switches; and

means, activated in response to running of the engine, for preventing the condition of the first switch from affecting engine ignition apart from the second switch during running of the engine.

3. In a machine driven by an internal combustion engine that has a magneto ignition system and having at least two safety switches, each separately operable, a first safety switch indicative of power transmission from the engine to a movable part of the machine and a second indicative of operator presence at controls of the machine;

a safety interlock comprising electrical circuitry including;

a first solid state switch selectively operable to short the ignition to prevent start of the engine, dependent upon the condition of the first safety switch and independent of the condition of the second safety switch;

a second solid state switch selectively operable to short the ignition to prevent engine running after start, dependent upon the condition of both the first and second safety switches; and

means, activated in response to running of the engine, for preventing the condition of the first safety switch from affecting engine ignition apart from the second safety switch during running of the engine.

4. In a machine driven by an internal combustion engine that has a magneto ignition system and having at least two switches, each separately operable, a first switch indicative of operator presence at controls of the machine and a second indicative of power transmission from the engine to a moving part of the machine, a safety interlock comprising:

a first solid state switch selectively operable to short the ignition to prevent start of the engine, dependent upon the second switch indicating transmission of power to the machine and independent of the condition of the first switch;

a second solid state switch selectively operable to short the ignition to prevent engine running after start, dependent upon the second switch indicating transmission of power to the machine and the first switch failing to indicate presence of an operator at the controls; and

memory means, activated in response and sensitive to running of the engine, for preventing the condition of the second switch from affecting engine ignition apart from the first switch during running of the engine.

5. In a machine operated selectively through a transmission by an internal combustion engine that has a magneto ignition system having a primary winding that can be shorted to prevent ignition, the machine having a station to be occupied by an operator and a safety interlock for controlling the starting and running of the engine, said interlock comprising:

a first switch means connected across a primary winding of the ignition system, normally nonconductive and capable of being rendered conductive by an electrical signal;

a second switching means connected across the primary winding, normally nonconductive and capable of being rendered conductive by an electrical signal;

a first control circuit for said first switching means, including first safety switch means for actuation in response to the condition of the transmission driven by said engine, said first safety switch means having a first non-conductive condition that allows the first switching means to become conductive upon engine starting and a second conductive condition that prevents it from becoming conductive, and circuit means responsive to running of the engine to prevent the first switching means from becoming conductive while the engine is running;

a second control circuit including said first safety switch means and a second safety switch means for actuation in response to the condition of the station to be occupied by an operator, said first safety switch means in its second condition preventing the second switching means from becoming conductive, and said second safety switch means having a first conductive condition that prevents the second switching means from becoming conductive and a second non-conductive condition that allows the second switching means to become conductive if the first safety switch means is in its first condition;

whereby the ignition system is disabled when (a) the engine is not running and the first safety switch means is in the first condition, and (b) the engine is running and the first safety switch means is in the first condition and the second safety switch means is in the second condition.

6. In a machine driven by an internal combustion engine that has a magneto ignition system and having at least two switches each separately operable, a first switch that is open when a power transmission from the engine to a movable part of the machine is engaged and a second switch that is closed when an operator is present at the operating controls of the machine;

a safety interlock comprising;

a first electronic control operable to disable the ignition to prevent start of the engine dependent upon the condition of the first switch and independent of the condition of the second switch;

a second electronic control operable for stopping the running of the engine after start in response to a condition of both the first and second switches;

said first electronic control operating independently of said second electronic control in preventing start of the engine and said second electronic control operating independently of said first electronic control in stopping the running of the engine after start; and

means preventing operation of said first control during running of the engine.

7. In a machine driven by an internal combustion engine that has a magneto ignition system and having at least two switches, each separately operable, a first switch indicative when open of power transmission from the engine to a moving part of the machine and a second indicative when closed of operator presence at controls of the machine, a safety interlock comprising:

a first solid state switch selectively operable to short the ignition to prevent start of the engine, dependent upon the first switch indicating transmission of power to the machine and independent of the condition of the second switch;

a second solid state switch selectively operable to short the ignition to prevent engine running after start, dependent upon the first switch indicating transmission of power to the machine and the second switch failing to indicate presence of an operator at the controls; and

memory means, including a capacitor, activated in response and sensitive to running of the engine, for preventing the condition of the first switch from affecting engine ignition apart from the second switch during running of the engine.