SAFETY SYSTEM FOR ENGINE OVERTURNING

Abstract: A safety system against engine overturning comprises an inclination sensor (15) for detecting an engine inclination and transmitting a signal representing the engine inclination and a self-hold means (5) operatively connected to the inclination sensor (15). The self-hold means (5) determines an inclined condition of the engine in response to the signal from the inclination sensor (15) and transmits and holds an engine stopping signal in a case where the detected engine inclination exceeds a preliminarily set allowable inclination. The operation of the engine is stopped in response to the engine stopping signal from the self-hold means (5). The driving condition of the engine and a fuel pump (18) are determined and controlled by driving condition determining means (11) serving to drive the fuel pump (18) when an engine speed exceeds a preliminarily set reference value while to stop the fuel pump (18) when the engine stopping signal is transmitted from the self-hold means (5).

Description: The present invention relates to a safety system responsive to overturning of an engine with a fuel pump, comprising: inclination detecting means for detecting an engine inclination and for transmitting an inclination signal; self-hold means responsive to the inclination signal for determining an inclined condition of the engine and for transmitting and holding an engine stopping signal, when the inclination exceeds a preliminarily set allowable inclination; engine stopping means responsive to the engine stopping signal for stopping an operation of the engine; and driving condition determining means responsive to the engine stopping signal for stopping an operation of the fuel pump. Such a system has been known from the abstract of JP-A-59 231 162. A construction equipment or machine such as a small sized roller or a small sized snowplow equipped with an industrial utility engine is generally provided with an inclination sensor for detecting an inclination of the engine greater than a predetermined angle and for alarming or temporarily stopping the operation of the engine. Such an alarm or temporarily stopping the engine preliminarily indicates that the engine may be overturned. However, since the weight balance of the construction equipment is usually instable, the equipment or machine may be liably overturned on an inclined ground. There will be less time between the alarming and the actual overturning and, hence, it may be difficult for workers to take necessary procedure to prevent the machine from overturning before it is overturned. Japanese Utility Model Laid-open Publication No. 59-40573 discloses a safety control device wherein the operation of a fuel pump is stopped at a time when a certain abnormal impact applied to a vehicle or a machine body is detected to cut off the fuel supply to the engine thereby preventing a secondary disaster such as a fire caused by the overturn of the engine. However, the safety control device described above does not operate to cut off the fuel supply till an abnormal impact is detected, so that it may be difficult to quickly respond to the overturning and to effectively avoid the overflow of the fuel on the way of the overturning. US-A-3 47O 854 discloses a system with a starter motor switch actuated to start the operation of an engine and with input processing means for converting an output signal from the starter motor switch into a forced driving signal. An object of the present invention is to provide a safety system capable of effectively avoiding a secondary disaster after the overturning of an engine. This and other objects are achieved according to the present invention by providing in a safety system known from the abstract of JP-A-59 231 162 a starter motor switch actuated to start the operation of the engine; input processing means for converting an output signal from the starter motor switch into a forced driving signal; an ignition unit generating an alternating voltage to make an ignition plug spark; waveform processing means for shaping a waveform of the alternating voltage into a rectangular waveform; pulse count processing means responsive to the rectangular wave for calculating an engine speed; reference value generation means for generating a reference speed representing an occurance of an initial explosion in the engine; and comparing means for comparing the engine speed with the reference speed and for producing a motor driving signal when the engine speed exceeds the reference speed; said driving condition determining means being responsive to the forced driving signal and to the motor driving signal for driving the fuel pump unless the engine stopping signal is received. According to this safety system, the inclined condition of the engine is first determined in response to the output signal from the inclination detecting means. When the engine inclination exceeds the preliminarily set allowable inclination, the engine stopping signal is generated and the output condition of the engine stopping signal is self-held. When the engine operation stopping signal is generated, the operation of the engine is stopped. When the engine speed exceeds the preliminarily set reference speed, the fuel pump is driven by the driving condition determining means, which, however, stops the operation of the fuel pump when the engine stopping signal is generated from the self-hold means. Accordingly, when the engine is inclined by an angle greater than an allowable angle, the operation of the engine as well as the fuel pump is immediately stopped and the stopped condition can be held thereby effectively preventing a secondary disaster in case of overturning the engine. Preferred embodiments of the present invention will become understood from the following detailed description referring to the accompanying drawings. Fig. 1 is a view showing an arrangement of a safety system for an engine unit according to the present invention; Fig. 2 is a detailed block diagram of a first embodiment of the safety system of Fig. 1; and Fig. 3 is a detailed block diagram of a second embodiment of the safety system. of Fig. 1. Referring to Fig. 1, a fuel supplying unit 2OO is disposed for an engine unit 1OO and is provided with a fuel pump 3OO. Fuel in a fuel tank 4OO is supplied to an injector 6OO, then to the engine unit 1OO by the fuel pump 3OO through a fuel supply pipe 5OO. The driving conditions such as engine speed of the engine unit 1OO and the operation of the fuel pump 3OO are controlled by a control unit 7OO in response to output signals from respective sensors 8OO including a sensor for detecting an inclination of the engine unit 1OO. An ignition unit 9OO is also connected to the control unit 7OO. Referring to Fig. 2, a control unit 1 (equivalent to 7OO in Fig. 1) of the safety system is composed of waveform processing means 2, sensor signal processing means 3, input processing means 4, self-hold means 5, engine stopping means 6, pulse count processing means 7, reference value generation means 8, comparing means 9, forced driving condition determining means l0, driving condition determining means ll and a driving circuit l2. A primary side of an ignition coil in an ignition unit l3 (900 in Fig. l) is connected to the waveform processing means 2 and a secondary side of the ignition coil in the ignition unit l3 is connected to an ignition plug l4. The sensor signal processing means 3 is connected to an inclination sensor l5 (800 in Fig. l), for detecting the inclination of the engine, connected to an engine, not shown, or a machine body to which the engine is mounted. The inclination sensor l5 is, for example, composed of a magnetic resisting element, a potentiometer, a lead switch or a mercury switch for transmitting a signal corresponding to the inclination angle or a signal generated at a time when the inclination of the engine is beyond a predetermined inclination angle. A power source Vcc such as battery is connected to the input processing means 4 through a starter motor switch l6 and a power switch l7. The starter motor switch l6 is made "ON" after the power switch l7 has been made "ON". An electrically driven fuel pump l8 (300 in Fig. l) is connected to the driving circuit l2. The operations of the respective means constituting the safety system against overturning according to the present invention shown in Fig. 2 will be described hereunder. The waveform processing means 2 performs the waveform shaping of an alternating voltage wave generated on the primary side of the ignition coil into a rectangular wave. The sensor signal processing means 3 has a timer function or a delay function to prevent generation of a false signal due to the road condition because inclination sensor l5 is sensitively reactive to an instantaneous operation. The input signal processing means 4 converts a signal inputted at a time when the power switch l7 and the starter motor switch l6 are made "ON" into an inner processing signal, i.e. a forced driving signal. In a case where the inclination sensor l5 is of the type having a magnetic resisting element or potentiometer which generates an output corresponding to the inclination angle of the engine, the self-hold means 5 compares a signal representing the inclination angle generated from the sensor signal processing means 3 with a preliminarily set allowable inclination angle. And in a case where the inclination angle exceeds the allowable inclination angle, the self-hold means 5 transmits an engine stopping signal and self-holds the output condition of the engine stopping signal. On the other hand, in a case where the inclination sensor l5 is of the type having the lead switch or the mercury switch which generates an output signal when the inclination angle exceeds the predetermined allowable inclination angle, the self-hold means 5 outputs an engine stopping signal in response to the signal from the sensor signal processing means 3 and to self-hold the output condition of the engine stopping signal. The engine stopping means 6 is connected between the primary side of the ignition coil in the ignition unit l3 and the waveform processing means 2 to make short circuit the primary side of the ignition coil and to extinguish the ignition plug l4 when the engine stopping signal is transmitted from the self-hold means 5. The engine stopping means 6 may be composed of a breakless circuit utilizing thyristor or transistor means, or relay switch means. The pulse count processing means 7 count the signals generated from the waveform processing means 2 and calculate or index the engine speed. In a case where the engine stopping signal is outputted from the self-hold means 5, the signal counting is stopped or the output signal from the waveform processing means 2 is made "0". The pulse count processing means 7 may be composed of an F/V converting circuit or a pulse rate circuit. The reference value generating means 8 generates a signal representing the reference value corresponding to a preliminarily set engine speed for determining an initial explosion of the engine. The comparing means 9 compares the engine speed indexed by the pulse count processing means 7 with the reference value generated from the reference value generating means 8. The comparing means 9 transmits a pump driving signal when the engine speed is above the reference value while transmits a pump stopping signal when the engine speed is below the reference value. The forced driving condition determining means l0 transmits a pump stopping signal irrespective of the transmission of the forced driving signal from the input processing means 4 in a case where the engine stopping signal is transmitted from the self-hold means 5. The forced driving condition determining means l0 also transmit a pump driving signal in a case where the engine stopping signal is not transmitted from the self-hold means 5 and where the forced driving signal is transmitted from the input processing means 4, i.e. where the starter motor switch l6 is switched "ON" to drive the cell motor. The driving condition determining means ll serves in response to the control signal from the forced driving condition determining means l0 irrespective of the output signal from the comparing means 9 in a case where the control signal is transmitted from the forced driving condition determining means l0, whereas the driving condition determining means ll is operated in response to the control signal from the comparing means 9 in a case where the control signal is not transmitted from the forced driving condition determining means l0. Namely, in a case where the pump driving signal is transmitted from the forced driving condition determining means l0 or where the control signal is not transmitted from the forced driving condition determining means l0 and the pump driving signal is transmitted from the comparing means 9, the driving condition determining means ll generates a pump driving signal. To the contrary in a case where the pump stopping signal is transmitted from the forced driving condition determining means l0 or where the forced driving signal is not transmitted from the forced driving condition determining means l0 and the pump stopping signal is transmitted from the comparing means 9, a pump stopping signal is generated from the driving condition determining means ll. The driving circuit l2 outputs a driving signal or stopping signal to the fuel pump l8 in response to the output signal from the driving condition determining means ll. In Fig. 2, reference numeral l9 designates a manual stop switch. The first embodiment of the present invention of the construction or character described above will operate as follows. At the initial engine starting time, when the power switch l7 is made "ON" and the starter motor switch l6 is then made "ON", the forced driving signal is outputted from the input processing means 4 to the forced driving condition determining means l0. In the meantime, when the engine is started at the location on a flat ground, the engine stopping signal is not generated from the self-hold means 5 and, hence, the pump driving signal is transmitted from the forced driving condition determining means l0 to the driving circuit l2 through the driving condition determining means ll. The fuel pump l8 is then forcibly driven by the operation of the driving circuit l2. After the starting of the engine, when the starter motor switch l6 is switched to "OFF", the output of the forced driving signal from the input processing means 4 is stopped and the output of the control signal from the forced driving condition determining means l0 is stopped. Then, after the initial explosion of the engine has been completed, when the engine speed calculated by the pulse count processing means 7 exceeds the reference value (reference engine speed for determining the initial explosion) from the reference value generation means 8, the pump driving signal is transmitted from the comparing means 9 to the driving condition determining means ll, thereby driving the fuel pump l8. Accordingly, the fuel pump l8 can be driven continuously even in the "OFF" condition of the starter motor switch l6. When the inclination of a machine body equipped with the engine is beyond the allowable inclination angle the engine operation stopping signals are transmitted to the engine stopping means 6, the pulse count processing means 7 and the forced driving condition determining means l0 from the self-hold means 5 into which the output signal from the inclination sensor l5 is inputted through the sensor signal processing means 3. The self-hold means 5 holds the output condition of the engine stopping signal. At this moment, the primary side of the ignition coil in ignition unit l3 is short-circuited by the engine stopping means 6 and the ignition plug l4 is extinguished. A false signal having an appearance value of "0" of the engine speed is then transmitted from the pulse count processing means 7 to the comparing means 9, from which the pump stopping signal is transmitted to the driving condition determining means ll. The pump stopping signal is also transmitted from the forced driving condition determining means l0 to the driving condition determining means ll. The pump stopping signal is then transmitted from the driving condition determining means ll to the fuel pump l8 through the driving circuit l2, thus immediately stopping the operation of the fuel pump l8. As described hereinabove with reference to the first embodiment of the present invention, when the inclination of the machine body exceeds the allowable inclination angle, the primary side of the ignition coil is earthed and the operation of the fuel pump l8 is immediately stopped. Therefore, the fuel pump l8 is not operated while the engine is rotated by the inertia and, hence, an adverse phenomenon such as over-flow of the fuel can be effectively prevented. Moreover, as described above, in the engine overturning, since there is less time between the time when the inclination of the machine body exceeds the allowable inclination and the time when the machine body is actually overturned once, twice --- on an inclined ground, the output value from the inclination sensor l5 repeatedly indicates the overturned condition and the normal condition. However, since the self-hold means 5 can hold the output condition of the engine stopping signal, the engine is not erroneously driven and the fuel pump is not also erroneously operated. Furthermore, in the overturned condition of the machine body, even if the starter motor switch l6 is erroneously switched "ON", the fuel pump l8 is not erroneously driven because the engine stopping signal is inputted into the forced driving condition determining means l0 from the self-hold means 5. In a case where wire breaking of a harness of the manually operative stop switch l9 and the disconnection of the connector are caused, the fuel pump l8 is not operated in response to the engine stopping signal from the self-hold means 5, so that the fuel is never supplied and the engine can be surely stopped. Since the calculation of the engine speed by the pulse count processing means 7 is performed in response to the output signal from the ignition unit l3, the engine speed calculated by the pulse count processing means 7 is made "0" even in a case where the ignition coil in the ignition unit l3 is broken or damaged at an engine overturning time, for example, and the self-hold means 5 is broken. Thus, the driving of the fuel pump l8 stops. The engine stopping signal transmitted from the self-hold means 5 can be held till the power switch l7 is once switched "OFF". Consequently, as described above, any secondary disaster or damage caused by the overturning of the engine can be effectively avoided. As can be seen from the block diagram of Fig. 3, the second embodiment is one composed by simplifying the first embodiment, in which the driving condition of the fuel pump l8 is determined only by the driving condition determining means ll. Referring to Fig. 3, in a case where the engine stopping signal is inputted into the driving condition determining means ll from the self-hold means 5, the driving condition determining means ll transmits the pump stopping signal into the driving circuit l2 irrespective of the signal inputted from the input processing means 4 and the comparing means 9. In a case where the engine stopping signal is not transmitted from the self-hold means 5, the operation of the fuel pump l8 is controlled in response to the output signals from the input processing means 4 and the comparing means 9. While the presently preferred embodiments of the present invention have been shown and described, it is to be understood that these disclosures are for the purpose of illustration and that various changes and modifications may be made, for example, a unit for detecting wire breaking and imperfect contact of the inclination sensor l5 may be incorporated in the control unit l of the safety system of the present invention.

Claims: A safety system responsive to overturning of an engine with a fuel pump (18), comprising: inclination detecting means (15) for detecting an engine inclination and for transmitting an inclination signal; self-hold means (5) responsive to the inclination signal for determining an inclined condition of the engine and for transmitting and holding an engine stopping signal, when the inclination exceeds a preliminarily set allowable inclination; engine stopping means (6) responsive to the engine stopping signal for stopping an operation of the engine; and driving condition determining means (11) responsive to the engine stopping signal for stopping an operation of the fuel pump (18), characterized in that the system comprises: a starter motor switch (16) actuated to start the operation of the engine; input processing means (4) for converting an output signal from the starter motor switch (16) into a forced driving signal; an ignition unit (13) generating an alternating voltage to make an ignition plug (14) spark; waveform processing means (2) for shaping a waveform. of the alternating voltage into a rectangular waveform; pulse count processing means (7) responsive to the rectangular wave for calculating an engine speed; reference value generation means (8) for generating a reference speed representing an occurrence of an initial explosion in the engine; and comparing means (9) for comparing the engine speed with the reference speed and for producing a motor driving signal when the engine speed exceeds the reference speed; said driving condition determining means (11) being responsive to the forced driving signal and to the motor driving signal for driving the fuel pump (18) unless the engine stopping signal is received. The safety system according to claim 1, wherein said inclination detecting means is an inclination sensor (15) generating the inclination signal corresponding to an inclination angle of the engine and the self-hold means (5) serves to compare the inclination angle with a preliminarily set allowable inclination angle and to transmit and self-hold the engine stopping signal when the inclination angle exceeds the allowable inclination angle. The safety system according to claim 1, wherein the inclination detecting means is an inclination sensor (15) generating an output when the inclination exceeds the preliminarily set allowable inclination, and the self-hold means serves to output and self-hold the engine stopping signal in response to the signal from the inclination sensor (15) through the sensor signal processing means (3). The safety system according to claim 1, wherein said engine stopping means (6) comprises a breakerless circuit including a thyristor or transistor. The safety system according to claim 1, wherein said pulse count processing means (7) includes an F/V converter or a pulse rate circuit. The safety system according to claim 1, wherein said comparing means (9) serves to output a pump stopping signal, when the detected engine speed is less than the reference speed to stop the fuel pump (18). The safety system according to claim 1, wherein said driving condition determining means (11) includes a forced driving condition determining means (10) which transmits a pump stopping signal irrespective of an output signal from said input processing means (4), when the engine stopping signal is generated from said self-hold means (5), and which transmits a pump driving signal, when the engine stopping signal is not transmitted from the self-hold means (5) and a forced driving signal is generated from the input processing means (4).

Inventors: SASAKI, ASAO
Applicants: FUJI JUKOGYO KABUSHIKI KAISHA
Application year: 1990
Main classification: F02D41
IPC codes: F02D41, F02D17, A01K63, F02D45, B60K28, G09F19