IGNITION DEVICE FOR AN INTERNAL COMBUSTION ENGINE

Description

State of the art

[0001] The invention relates to an ignition device for an internal combustion engine according to the preamble of the main claim.

[0002] An ignition device for an internal combustion engine is already known from DE102013202016 A1, comprising a primary circuit and a secondary circuit, wherein the primary circuit has a primary coil, and wherein the secondary circuit comprises a secondary coil inductively coupled to the primary coil, a diode for spark suppression, and a high-voltage terminal for connection to a spark plug. Further ignition devices are described in publications US 6 116 226 A or US 7 418 956 B2.

[0003] After each ignition, residual energy in the form of a residual voltage may remain in the secondary circuit of the ignition device, which in the worst case leads to an undesired ignition and as a result can cause damage to the intake tract of the internal combustion engine, for example to the throttle valve and / or the intake manifold. Advantages of the invention

[0004] The ignition device according to the invention with the characterizing features of the main claim has the advantage that unwanted ignition is excluded or at least avoided by forming a parallel path electrically parallel to the diode of the secondary circuit. According to a first variant, an ohmic load resistor or, according to a second variant, an electrical switch can be arranged in the parallel path. Residual energy, in particular residual voltage, remaining in the secondary circuit after a discharge of the ignition device can be extinguished by means of the parallel path, in particular by conducting the residual energy in the secondary circuit past the diode, bypassing the diode.

[0005] The measures listed in the subclaims enable advantageous further developments and improvements of the ignition device specified in the main claim.

[0006] According to the invention, the ohmic load resistance of the parallel path according to the first embodiment has an electrical resistance which is greater than 1 MOhm and / or which is in particular in the range between 10 MOhm and 100 MOhm.

[0007] In this way, on the one hand, an electrically conductive connection for the residual energy is provided in the parallel path at all times and, on the other hand, the switch-on spark suppressing effect of the diode is only slightly weakened, thus ensuring that no switch-on sparks are generated when the primary current is switched on in the primary circuit.

[0008] It is also advantageous if the ohmic load resistor of the parallel path according to the first embodiment is a wired resistor, an SMD resistor, or a ladder resistor. If the diode is implemented on a printed circuit board, for example, as an SMD component, a load resistor designed as an SMD resistor would be advantageous. If the diode is a wired component, a wired load resistor or a ladder resistor would be advantageous.

[0009] It is very advantageous if the conductor resistor comprises an electrically conductive material in the form of a layer, coating, conductor track, or sheath. For example, the entire parallel path is designed as a continuous conductor resistor. This allows the load resistor to be implemented particularly cost-effectively.

[0010] It is also advantageous if the conductor resistor is arranged and / or formed on the surface of the diode. In this way, the diode forms a support element for the load resistor and for the formation of the parallel path. It is also advantageous if the electrical switch of the parallel path is designed to be switched at a suitable time between a spark break and a renewed recharging of the primary circuit. In this way, the switch can be switched to the closed state at the suitable time, whereby the parallel path for the residual energy is switched through, so that the residual energy can be conducted past the diode, bypassing the diode, which leads to the residual energy being extinguished. The switch of the parallel path can, for example, be a semiconductor switch, in particular a transistor.

[0011] It is also advantageous if the parallel path is connected with its terminal ends to the terminals of the diode.

[0012] Furthermore, it is advantageous that the residual energy for cancellation can be conducted via the parallel path to an electrical ground, in particular via the primary circuit or via a ground connection of the secondary circuit.

[0013] It is further advantageous that the secondary coil has a first coil end facing the high-voltage terminal and a second coil end facing away from the high-voltage terminal, wherein the secondary circuit has a high-voltage path connected to the first coil end of the secondary coil and a ground path connected to the second coil end of the secondary coil. According to the invention, the diode can be arranged in the ground path or in the high-voltage path.

[0014] It is advantageous if the ignition device according to the invention is formed on an ignition coil and thus arranged in a self-contained unit. Integrating the ignition device into the ignition coil offers advantages in terms of electrical insulation and installation space. drawing

[0015] Three embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description. Fig.1 shows an ignition device according to the invention according to a first embodiment with a parallel path according to a first variant, Fig.2 shows an ignition device according to the invention according to the first embodiment according to Fig.1 with a parallel path according to a second variant, Fig.3 an ignition device according to the invention according to a second embodiment with a parallel path according to the first variant and Fig.4 an ignition device according to the invention according to a third embodiment with a parallel path according to the first variant. Description of the embodiments

[0016] Fig.1 shows in the form of an equivalent circuit diagram an ignition device according to the invention according to a first embodiment with a parallel path according to a first variant.

[0017] The ignition device 1 according to the invention serves to generate a high electrical voltage for generating an ignition spark for operating an internal combustion engine, for example, a hydrogen-powered internal combustion engine. The internal combustion engine serves, for example, to drive a vehicle.

[0018] The ignition device 1 according to the invention comprises a transformer 2 with a primary circuit 2.1 and a secondary circuit 2.2. The primary circuit 2.1 has a primary coil 3. The secondary circuit 2.2 comprises a secondary coil 4 inductively coupled to the primary coil 3, a diode 5 for spark suppression, and a high-voltage terminal 6 for connection to a spark plug 7. The ignition device 1 according to the invention can be implemented partially or entirely on an ignition coil.

[0019] According to the invention, a parallel path 10 is formed electrically parallel to the diode 5 of the secondary circuit 2.2, in which, according to the first variant, an ohmic load resistor 11 is arranged and by means of which residual energy, in particular a residual voltage that remains in the secondary circuit 2.2 after a discharge of the ignition device 1, can be extinguished. The extinguishing of the residual energy occurs in that the residual energy in the secondary circuit 2.2 can be conducted via the parallel path 10, bypassing the diode 5, and can be conducted to an electrical ground. According to the first exemplary embodiment, the residual energy can reach the electrical ground via the primary circuit 2.1, for example, via a low-voltage connection 12 of the primary circuit 2.1. The low-voltage connection 12 of the primary circuit 2.1 is provided, for example, for connection to a positive terminal of a vehicle battery.

[0020] The parallel path 10 therefore provides an electrically conductive connection for the residual energy at all times, without losing or canceling out the switch-on spark-suppressing effect of the diode 5. To achieve this, the ohmic load resistor 11 of the parallel path 10 has, for example, an electrical resistance that is greater than 1 MOhm and, for example, lies in the range between 10 MOhm and 100 MOhm. The ohmic load resistor 11 of the parallel path 10 can, for example, be a wired resistor, an SMD resistor, or a ladder resistor. If the load resistor 11 is designed as a ladder resistor, an electrically conductive material is provided for the ladder resistor, which can be designed, for example, as a layer, coating, conductor track, or sheath. The sheath can, for example, be an electrically conductive shrink tube.The layer, coating, or conductor track can be printed, vapor-deposited, or sputtered, for example. The load resistor 11, designed as a conductor resistor, can be arranged and / or formed, for example, on the surface of the diode 5 or on a diode body of the diode 5.

[0021] The parallel path 10 can be connected with its terminal ends 10.1 to the terminals 5.1 of the diode 5. The conductor resistance can, for example, extend along the surface of the diode 5 to the terminals 5.1 of the diode 5.

[0022] The secondary coil 4 has a first coil end 4.1 facing the high-voltage connection 6 and a second coil end 4.2 facing away from the high-voltage connection 6, wherein the secondary circuit 2.2 has a high-voltage path 13 connected to the first coil end 4.1 of the secondary coil 4 and a ground path 14 connected to the second coil end 4.2 of the secondary coil 4.

[0023] Diode 5 can be arranged at any location in secondary circuit 2.2, i.e., in ground path 14 or in high-voltage path 13, and in each case has the parallel path 10 according to the invention. According to the first embodiment, diode 5 is arranged in ground path 14, with ground path 14 being connected to primary circuit 2.1 according to the so-called economy circuit, in that a terminal 5.1 of diode 5 is electrically connected to low-voltage terminal 12 of primary circuit 2.1.

[0024] The primary coil 3 of the primary circuit 2.1 has a first coil end 3.1 and a second coil end 3.2, wherein the first coil end 3.1 is electrically connected to the low-voltage terminal 12 and wherein the second coil end 3.2 is electrically connected or electrically connectable to an ignition output stage 15 provided for switching the primary current in the primary circuit 2.1. According to the exemplary embodiments, the ignition output stage 15 is part of the ignition device 1 according to the invention, but this can expressly also be implemented outside the ignition device 1, for example in an engine control unit. In addition to the connection to the second coil end 3.2 of the primary coil 3, the ignition output stage 15 has a terminal 15.1 for connection to an electrical ground, for example a body or vehicle ground.

[0025] Fig.2 shows an ignition device according to the invention according to the first embodiment according to Fig.1 with a parallel path according to a second variant.

[0026] The ignition device according to Fig.2 differs from the ignition device according to Fig.1 merely in the design of the parallel path 10. According to the second variant, no ohmic load resistor 11 is provided in the parallel path 10, but rather an electrical or electronic switch 20. The switch 20 of the parallel path 10 is configured to be switched to the closed state at a suitable time between a spark interruption of a previous ignition and a renewed recharging of the primary circuit 2.1. As a result, the parallel path 10 is electrically switched through at the appropriate time, so that residual energy can be extinguished at the appropriate time. The switch 20 can, for example, be a semiconductor switch, in particular a transistor.

[0027] Fig.3 shows in the form of an equivalent circuit diagram an ignition device according to the invention according to a second embodiment with a parallel path according to the first variant with the ohmic load resistance.

[0028] According to the second embodiment, diode 5 is arranged in ground path 14, as in the first embodiment. According to the invention, parallel path 10 is provided electrically parallel to diode 5 of secondary circuit 2.2.

[0029] The second embodiment differs from the first embodiment in Fig.1 merely in that the ground path 14 is not connected to the primary circuit 2.1, but via a ground connection 17 to an electrical ground, for example a vehicle ground.

[0030] The parallel path 10 according to the invention can of course also be designed in the second embodiment according to the second variant with the switch 20.

[0031] Fig.4 shows in the form of an equivalent circuit diagram an ignition device according to the invention according to a third embodiment with a parallel path according to the first variant.

[0032] The third embodiment differs from the second embodiment in Fig.3 merely in that diode 5 is not arranged in ground path 14, but in high-voltage path 13. According to the invention, parallel path 10 is provided electrically parallel to diode 5 of secondary circuit 2.2. In the third embodiment, as in the second embodiment, ground path 14 is connected to an electrical ground, for example, a vehicle ground, via ground terminal 17.

[0033] The parallel path 10 according to the invention can of course also be designed in the third embodiment according to the second variant with the switch 20.

Claims

1. Ignition device (1) for an internal combustion engine, in particular for a hydrogen-operated internal combustion engine, having a primary circuit (2.1) and a secondary circuit (2.2), wherein - the primary circuit (2.1) has a primary coil (3), wherein - the secondary circuit (2.2) has a secondary coil (4) inductively coupled to the primary coil (3), a diode (5), and a high-voltage terminal (6) for connection to a spark plug (7), characterized in that - the diode (5) in the secondary circuit (2.2) is arranged in an orientation in which the current flow to the spark plug (7) is prevented in order to suppress the switch-on spark, - a parallel path (10) is formed electrically in parallel with the diode (5) of the secondary circuit (2.2), in which parallel path an ohmic load resistor (11) is arranged and by means of which parallel path residual energy, in particular residual voltage, which remains in the secondary circuit (2.2) following discharge of the ignition device (1), can be extinguished, by virtue of the residual energy in the secondary circuit (2.2) being able to be guided past the diode (5), bypassing the diode (5), and in that - the ohmic load resistor (11) of the parallel path (10) has an electric resistance that is greater than 1 MOhm, which is in particular in the range between 10 MOhm and 100 MOhm.

2. Ignition device (1) for an internal combustion engine, in particular for a hydrogen-operated internal combustion engine, having a primary circuit (2.1) and a secondary circuit (2.2), wherein - the primary circuit (2.1) has a primary coil (3), wherein - the secondary circuit (2.2) has a secondary coil (4) inductively coupled to the primary coil (3), a diode (5), and a high-voltage terminal (6) for connection to a spark plug (7), characterized in that - the diode (5) in the secondary circuit (2.2) is arranged in an orientation in which the current flow to the spark plug (7) is prevented in order to suppress the switch-on spark, - a parallel path (10) is formed electrically in parallel with the diode (5) of the secondary circuit (2.2), in which parallel path an electrical switch (20) is arranged and by means of which parallel path residual energy, in particular residual voltage, which remains in the secondary circuit (2.2) following discharge of the ignition device (1), can be extinguished, by virtue of the residual energy in the secondary circuit (2.2) being able to be guided past the diode (5), bypassing the diode (5), when the switch (20) is closed.

3. Ignition device according to Claim 1, characterized in that the ohmic load resistor (11) of the parallel path (10) is a wired resistor, an SMD resistor or a conductor resistor.

4. Ignition device according to Claim 3, characterized in that the conductor resistor comprises an electrically conductive material formed as a layer, coating, conductor track or sheath.

5. Ignition device according to either one of Claims 3 and 4, characterized in that the conductor resistor is arranged and / or formed on the surface of the diode (5).

6. Ignition device according to Claim 2, characterized in that the electrical switch (20) of the parallel path (10) is configured to be switched between a spark break and a recharging of the primary circuit (2.1) at a suitable time, wherein the switch (20) of the parallel path (10) is in particular a semiconductor switch, in particular a transistor.

7. Ignition device according to any one of the preceding claims, characterized in that the parallel path (10) is connected by way of its terminal ends (10.1) to terminals (5.1) of the diode (5).

8. Ignition device according to any one of the preceding claims, characterized in that the residual energy can be conducted to an electrical earth via the parallel path (10).

9. Ignition device according to any one of the preceding claims, characterized in that the secondary coil (4) has a first coil end (4.1) facing the high-voltage terminal (6) and a second coil end (4.2) facing away from the high-voltage terminal (6), wherein the secondary circuit (2.2) has a high-voltage path (13) connected to the first coil end (4.1) of the secondary coil (4) and an earth path (14) connected to the second coil end (4.2) of the secondary coil (4), wherein the diode (5) is arranged in the earth path (14) or in the high-voltage path (13).

10. Ignition coil, comprising an ignition device according to any one of the preceding claims.