ELECTROMAGNETIC VALVE ACTUATOR

Abstract

A solenoid valve actuator device (1) which drives a solenoid valve (Vx) by switching on and off a switching element (Trx) using a control signal (DRx) with a control cycle of a predetermined control duration (Tbase), wherein the switching element (Trx) is arranged in series with a coil (Lx) of the solenoid valve (Vx) in a current-sensing circuit and is configured to energize the coil (Lx), wherein the solenoid valve actuator device (1) comprises: a determining means (3, S110) configured to determine a current application duration (tone) during which current is to be applied to the coil (Lx) within the actuation duration (Tbase) of each actuation cycle of successive actuation cycles of the actuation signal (DRx), wherein a non-current application duration (Toff = Tbase - tone) is defined between an endpoint of the current application duration (tone) and an endpoint of the actuation duration (Tbase); a control signal output device (3; S140; 3, S240; 11 to 13) configured to output the control signal (DRx) to the switching element (Trx), in an active state to switch on the switching element (Trx) during a peak current duration (Tp), in a hold signal state during a holding current duration (Th) and in an inactive state to switch off the switching element (Trx) during the non-current duration (Toff), where the current supply duration (Ton) (i) the peak current supply duration (Tp), which starts with a starting point of the actuating cycle, and (ii) the holding current supply duration (Th), which follows the peak current supply duration (Tp), The peak current duration (Tp) is a duration during which the control signal (DRx) in the active state applies a peak current to the coil (Lx) to allow a valve body of the solenoid valve (Vx) to move from a standard position towards a position where operation is terminated. the holding current application time (Th) is a duration during which the control signal (DRx) in the holding signal state becomes a holding pulse follow signal which is in the active state with a predetermined duty cycle, wherein the holding pulse follow signal applies a holding current to the coil (Lx) which is smaller than the peak current but can maintain at least one position to which the valve body is moved from the standard position; a decision means (3, S120) configured to make a decision as to whether the non-supply duration (Toff) is equal to or less than a predetermined minimum value, each time the determining means (3, S110) determines the current supply duration (Ton) with respect to a current actuating cycle; and a signal shape change device (3, S130, S210, S230) configured to change the control signal (DRx) when the decision device (3, S120) makes a positive decision regarding the current control cycle, such that (i) with respect to the current control cycle, by eliminating the off-time (Toff), the specified current duration (Ton) is changed to be equal to the predetermined control duration (Tbase) in order to cause the control signal (DRx) to be the holding pulse sequence signal from the endpoint of the peak current duration (Tp) to a starting point of a next control cycle following the current control cycle, and (ii) with respect to the next control cycle, the control signal (DRx) is instead in the active state in a state in which peaks are suppressed in order to become a pulse-following signal with suppressed peaks during the peak current duration of the next control cycle, wherein the pulse-following signal with suppressed peaks in the active state has a duty cycle equal to or greater than the duty cycle of the holding pulse-following signal, wherein the minimum value used by the decision device (3, S120) is predetermined to be less than a delay period (Tcs) ranging from the time when the control signal (DRx) transitions from the hold signal state to the inactive state until the time when the valve body begins to return to the standard position.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to an electromagnetic valve driving device or an electromagnetic valve actuating device that drives or acts on an electromagnetic valve (solenoid valve). BACKGROUND OF THE INVENTION

[0002] A solenoid valve drive device drives a solenoid valve by turning on and off a switching element such as a MOSFET (field effect transistor) provided in series in an electrical circuit and applying an electric current to a coil of the solenoid valve, based on a control signal.

[0003] In the electromagnetic valve drive device, during a current application period for applying an electric current to the coil of the electromagnetic valve, the actuating signal is maintained in an active state by turning on the switching element for a predetermined peak current application period starting from the start point of the current application period. This applies a large peak current to the coil, which can promptly move the valve body of the electromagnetic valve. Following the above predetermined period, during a remaining period ending at an end point of the current application period, the actuating signal is formed as a pulse train signal in an active state with a predetermined duty ratio and a predetermined duty cycle. This limits the amount of current applied to the coil, thus saving energy (see, for example, JP H05-272391 A).

[0004] There is a case where the driven solenoid valve is a linear solenoid valve. Here, the method of changing the control signal to a pulse train signal during the current application period as described above and the method of performing PWM (Pulse Width Modulation) control of the current application period itself can be combined.

[0005] For example, as in Fig. 9, an electromagnetic valve driving device 100 having a linear solenoid valve uses a high-side driving form to dispose a switching element Tr (e.g., N-channel MOSET) upstream of a coil L of the electromagnetic valve V. Therefore, one end of the coil L is connected to the ground line, the power supply voltage VB is applied to the other end of the coil L, and the electric current flows into the coil L when the switching element Tr turns on.

[0006] In such an electromagnetic valve drive device 100, a control signal DR with a control cycle which is Fig. 9(e) is generated in the following process. In this example, when the control signal DR is in a high state, the switching element TR is turned on. That is, the active state of the control signal DR is a high state or high level.

[0007] According to Fig. 9(a), one control cycle of the control signal DR has a control duration Tbase, and a single pulse OS (one-shot pulse) is generated to have the same cycle as the control signal DR while remaining in the high state only for a predetermined peak duration Tp from the starting point of the control duration Tbase. As shown in Fig. 9(b), a pulse train signal (also referred to as a hold signal) HD is generated, which goes high at a predetermined duty cycle for a period shorter than the above set period Tbase. As shown in Fig. As shown in Figure 9(c), a base signal BA is then generated as a logical sum of the one-shot pulse OS and the hold signal HD.

[0008] In addition, in the electromagnetic valve driving device 100, as shown in Fig. 9(d), a control key signal DD is generated to be a PWM signal having the same cycle as the control cycle Tbase of the control signal DR and to transition to a high state during an earlier period Ton within a control cycle Tbase of the control signal DR, while transitioning to a low state during a later period Toff within the control cycle Tbase. With respect to the control key signal DD, an electric current is applied to the coil L during the earlier current application period Ton, whereas no electric current is applied to the coil L during the later non-current application period Toff. In other words, the earlier period Ton at which the control key signal is in the high state corresponds to a current application period during which an electric current is applied to the coil L.

[0009] In addition, in the electromagnetic valve driving device 100, as shown in Fig. As shown in Figure 9(e), a control signal DR is generated as a logical sum of the control key signal DD and the base signal BA. Therefore, the current application period Ton, during which the control key signal DD is in the high state, includes a period Tp during which the control key signal DD is in the high state, and a remaining period during which the control key signal is in the hold signal HD state. Furthermore, the control signal DR remains in the low state during the non-application period Toff.

[0010] Furthermore, as in Fig. 10(A), during a peak current application period Tp during which the actuating signal DR remains in the high state, a peak current Ip is applied to the coil L, so that the ON state of the switching element Tr continues to allow the valve body of the electromagnetic valve V to move from a standard position (i.e., a fully closed position) to a position at which the operation is completed (i.e., a fully opened position). Then, during a holding current application period after the peak current application period Tp, the actuating signal DR is in the state of the holding signal HD, and the switching element Tr is alternately switched to the ON state and the OFF state according to the holding signal HD. Thereby, a holding current Ih is applied to the coil L, which is smaller than the peak current Ip but allows the valve body to remain at least in the position at which the operation is completed.

[0011] When the control signal DR switches from the hold signal HD to the low state, the current flow to the coil L is stopped. Then the valve body of the solenoid valve V begins to return to the standard position. Fig. 10, "CURRENT" indicates a value of an electric current flowing into the coil of the solenoid valve. Furthermore, in the "VALVE" series, "CLOSED" or "OPEN" does not indicate a fully closed state or a fully opened state, respectively. The increase from "CLOSED" to "OPEN" indicates a time point "when the valve body begins to move to the position where the operation is completed." The decrease from "OPEN" to "CLOSED" indicates a time point "when the valve body begins to return to the standard position." This also applies to other drawings explained later.

[0012] The current application duration Ton is defined as the duration during which the control signal DR is in the high state or in the hold signal HD state. The ratio of the current application duration Ton to the control cycle Tbase (= Ton / Tbase) is called a duty cycle or a relative duty cycle of the control signal DR. This relative duty cycle of the control signal DR is called a control duty cycle to distinguish it from a duty cycle of a general pulse train signal (that is, a cycle is the sum of the high-state durations and the low-state durations of consecutive pairs). Furthermore, in this specification, a unit of a duty cycle is percent (%) unless otherwise specified.

[0013] In the above conventional electromagnetic valve driving device 100 as shown in Fig. As shown in Fig. 10(B), when the duty cycle is less than 100% but greater than a predetermined value, the valve body starts to move toward the position at which the operation is terminated upon entering the next duty cycle without completely returning to the standard position.

[0014] According to Fig. 10(A), a delay period or time Tcs is defined as a period from the time when the actuating signal DR transitions from the state of the holding signal HD to the low state until the target body starts to return toward the standard position. Assume the case where the actuating duty cycle becomes larger to cause the non-energization period Toff (= Tbase - Ton) to become shorter than Tcs. In such a case, although the actuating signal DR once transitions to the low state, the actuating signal DR again transitions to the high state due to the start of the next actuating cycle before the valve body starts to return to the standard position. The valve body thus continues to move toward the position at which the operation is completed without returning to the standard position.

[0015] Furthermore, when the valve body of the solenoid valve V is moved to the position where the operation is terminated, the duty cycle is generally gradually increased. When the duty cycle is set to the above predetermined value, the solenoid valve V is in the fully open state or the almost fully open state. In such a state, the valve body does not return toward the standard position even if the peak current Ip is not applied to the coil L. The open state of the solenoid valve V is maintained.

[0016] In a conventional solenoid valve drive device 100, the actuating signal DR is maintained high to apply the peak current Ip to the coil L for a predetermined peak current application period Tp, which begins at the start point of each actuating cycle. The electrical energy corresponding to the peak current Ip may be wasted.

[0017] Further prior art is also known from JP S63 - 203 982 A, JP H11 - 297 529 A and US 2009 / 0 015 979 A1. SUMMARY OF THE INVENTION

[0018] It is an object to provide a solenoid valve drive device that can avoid useless energy consumption. This object is achieved by the solenoid valve drive device having the features according to claim 1. Advantageous embodiments are the subject of the dependent claims.

[0019] According to one aspect of the present invention, an electromagnetic valve drive device is provided. The device drives an electromagnetic valve by switching a switching element on and off using an actuating signal with an actuating cycle of a predetermined actuating period, wherein the switching element is provided in series in a current application circuit for applying current to a coil of the electromagnetic valve. The electromagnetic valve drive device comprises: a determining means, an actuating signal output means, a decision means, and a signal shape changing means. The determining means serves to determine a current application period during which current is to be applied to the coil within the actuating period of each actuating cycle of successive actuating cycles of the actuating signal.wherein a non-energization period is defined between an end point of the current application period and an end point of the actuating period. This serves as an actuating signal output means for outputting the actuating signal to the switching element, in an active state for switching the switching element on during a peak current application period, in a holding signal state during a holding current application period, and in an inactive state for switching the switching element off during the non-energization period. The current application period includes the peak current application period, which starts at a starting point of the actuating cycle, and the holding current application period, which follows the peak current application period. The peak current application period is a period during which the actuating signal, in the active state, applies a peak current to the coil to enable a valve body of the solenoid valve toto move from a standard position toward a position at which the operation is terminated. The holding current application period is a period during which the actuating signal in the holding signal state becomes a holding pulse train signal having a predetermined duty cycle in the active state, wherein the holding pulse train signal applies a holding current to the coil that is smaller than the peak current but can maintain at least a position to which the valve body is moved from the standard position. The decision means serves to make a decision as to whether or not the non-application period is equal to or smaller than a predetermined minimum value each time the determining means determines the current application period with respect to a current actuating cycle. The signal shape changing means serves to change the actuating signal,when the decision means makes an affirmative decision with respect to the current actuating cycle, so that (i) with respect to the current actuating cycle, by eliminating the non-application period, the determined current application period is changed to be equal to the predetermined actuating period, thereby causing the actuating signal to be the sustaining pulse train signal from the end point of the peak current application period to a start point of a next actuating cycle following the current actuating cycle, and (ii) with respect to the next actuating cycle, the actuating signal is in a peak-suppressed state instead of in the active state to become a peak-suppressed pulse train signal during the peak current period of the next actuating cycle, the peak-suppressed pulse train signal being in the active state with a duty cycle equal to or greater than the duty cycle of the sustaining pulse train signal. Here, the minimum value,used by the decision means is predetermined to less than a delay period ranging from the time when the control signal changes from the hold signal state to the inactive state until the time when the valve body begins to return to the standard position.

[0020] Therefore, even if the actuating signal of the next actuating cycle does not enter the active state during the peak current application period, the valve body is maintained at least at the same position. That is, the case is assumed where the current application period Ton determined by the determining means is equal to or greater than "Tbase (actuating period) - Toffmin (minimum value)", and the decision means thus makes an affirmative decision, and further, the actuating signal of the current cycle changes from the holding pulse train signal to the inactive state without the waveform changing means operating. Even in such a case, the valve body does not return to the standard position until the current application period of the actuating signal of the next actuating cycle ends, because the non-current application period (Toff) is shorter than the delay period (Tcs) required for the valve body to begin returning to the standard position.

[0021] In addition to focusing on this point, by causing the waveform changing means in the electromagnetic valve driving device to operate even though the actuating signal of the next actuating cycle does not enter the active state during the peak current application period, the valve body is maintained at least at the same position.

[0022] The absence of a need for the control signal to enter the active state during the peak current application period indicates that the switching element does not remain in the ON state during the peak current application period. Thus, the electric current applied to the coil can be kept low. Therefore, unnecessary electrical energy consumption can be prevented.

[0023] If the decision means repeatedly makes a positive decision (in other words, the current application duration Ton determined by the determination means repeatedly becomes equal to or greater than “Tbase - Toffmin”), the control signal remains in the pulse train signal (hold pulse train signal and peak suppressed pulse train signal) over the multiple control cycles.

[0024] In contrast, the determining means cannot directly determine a value of the current application duration Ton, nor can it determine a value of the actuating duty cycle (Ton / Tbase) or the non-current application duration Toff. This is because the current application duration Ton can be determined when either the actuating duty cycle or the non-current application duration Toff is determined.

[0025] In addition, instead of deciding whether “Toff ≤ Toffmin” is satisfied or not, the decision means can decide whether the duty cycle or the current application time Ton has a value that satisfies “Toff ≤ Toffmin”. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other objects, features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the drawings.

[0027] They show: Fig. 1 is a diagram for explaining a configuration and a basic operation of a solenoid valve driving device according to an embodiment of the present invention; Fig. 2 is a flowchart showing processing executed by a microcomputer; Fig. 3 is a first diagram for explaining an operation according to the embodiment; Fig. 4 is a second diagram for explaining an operation according to the embodiment; Fig. 5 is a first diagram for explaining a first modification example; Fig. 6 is a second diagram for explaining a first modification example; Fig. 7 is a first diagram for explaining a second modification example; Fig. 8 is a second diagram for explaining a second modification example; Fig. 9 is a diagram for explaining a configuration and a basic operation of a solenoid valve driving device according to the prior art; and Fig. 10 is a diagram for explaining a problem of the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] A solenoid valve drive device according to an embodiment of the present invention will be explained with reference to the drawings. The solenoid valve drive device of the present embodiment drives a plurality of linear solenoid valves (three in the present embodiment) provided, for example, in a hydraulic route for controlling an automatic transmission of a vehicle.

[0029] As in Fig. As shown in Figure 1(A), one end terminal of each of the coils L1 to L3 of three linear solenoid valves V1 to V3 (also referred to as an electromagnetic valve) is connected to a ground line. The other end terminal of each of the coils L1 to L3 is connected to each of the terminals J1 to J3 of the electromagnetic valve drive device 1.

[0030] The electromagnetic valve driving device 1 includes switching elements Tr1 to Tr3 (that is, an N-channel MOSFET in the present embodiment) for applying an electric current to the correspondingly associated coils L1 to L3 of the correspondingly associated electromagnetic valves V1 to V3.

[0031] One output terminal (i.e., drain) of each switching element Trx (i.e., one of Tr1, Tr2, Tr3) is connected to a battery voltage VB, which is a power source voltage; the other output terminal of each switching element (i.e., source) is connected to a terminal opposite to the ground line terminal of the coil Lx via the terminal Jx of the electromagnetic valve drive device 1. When the switching element Trx turns ON, the battery voltage VB is applied to the terminal opposite to the ground line terminal of the coil Lx. Thus, electric current is applied to this coil Lx, and the electromagnetic valve Vx is driven toward the open state or open side.

[0032] Furthermore, the above switching elements Tr1 to Tr3 are built into an output driver 2 included in the solenoid valve drive device 1. The output driver 2 is an IC that includes various elements and logic circuits such as the switching elements Tr1 to Tr3 in one package.

[0033] The solenoid valve drive device 1 further includes a microcomputer 3 that executes processing for controlling the solenoid valves V1 to V3. The output driver 2 generates control signals DR1 to DR3 to the switching elements Tr1 to Tr3 based on the signals output from the microcomputer 3, explained below. The output driver 2 outputs the generated control signals DR1 to DR3 to the control terminals (gates) of the switching elements Tr1 to Tr3. Each switching element Tr1 to Tr3 is switched to the ON state and the OFF state to drive the solenoid valves V1 to V3.

[0034] It should be noted that the control signals DR1 to DR3 in the electromagnetic valve drive device 1 are equal to the control signal DR in the electromagnetic valve drive device 100 in Fig. 9. With reference to DRx (DR1, DR2, DR3) in Fig. 1(B), a cycle and different durations are defined as follows. "Tbase" is a control cycle of each control signal DRx (DR1, DR2, DR3) with an identical fixed control duration with respect to each of the control signals DR1 to DR3. "Ton" is a current application duration that indicates a duration of current application to each coil Lx within the identical control cycle Tbase, wherein the current application duration Ton is varied depending on the control signal DRx. "Tp" is a predetermined peak current application duration during which the control signal DRx is in the high state or has the high level. The predetermined peak current application duration Tp starts from the cycle start point of the control cycle Tbase. “Ton - Tp” (also referred to as “Th”) is referred to as the holding current application period during which the control signal DRx is a holding signal (HD), which is a pulse train signal that is in the high state according to a predetermined duty cycle.The holding current application period Th has a cycle shorter than the actuating cycle Tbase of the actuating signal DRx. "Toff" (= "Tbase - Ton") is a non-application period during which the actuating signal DRx is in the low state. The non-application period Toff is a period ranging from the end point of the current application period Ton to the end point of the actuating cycle Tbase. Furthermore, in the case where "Ton - Tp" is positive (i.e., greater than zero), DRx is in . Fig. 1(B) by DR1 or DR2. In contrast, in the case where “Ton - Tp” is zero or negative (i.e., Ton ≤ Tp), the holding current duration vanishes, so that DRx in Fig. 1(B) is illustrated by DR3.

[0035] In one example of the present embodiment, the actuating cycle Tbase of the actuating signal DRx is 20 ms; the peak current application period Tp is 5 ms; the cycle of the holding signal HD is 0.25 ms; and the duty ratio of the holding signal HD is 50%.

[0036] Furthermore, as in Fig. As shown in Figure 1(B), the cycle start times of the control signals DR1, DR2, and DR3 are shifted from each other by at least the peak current application period Tp such that the peak current application periods Tp during which the control signals DR1 to DR3 are in the high states do not overlap. In the present embodiment, the cycle start points of the control signals are shifted from each other by the peak current application period Tp.

[0037] Such a mutual shift configuration is provided based on the following reasons. The peak current application period Tp starting from the cycle start point of the actuating cycle or actuating period Tbase is a period during which a peak current Ip is applied to the coil Lx so that the valve body of the solenoid valve Vx can be moved in a timely manner from the standard position (i.e., fully closed position) to the position at which the operation is completed (i.e., fully opened position). It assumes the case where the peak current application periods with respect to more than one actuating signal DRx are overlapped. In such a case, the peak current Ip is applied to the different coils at the same time, which temporarily reduces the battery voltage VB serving as a source voltage.To avoid such a reduction of the source voltage, the cycle start points of the control signals DR1 to DR3 are shifted from each other by the peak current application time Tp.

[0038] In addition, Fig. 1(B) Tonx (Ton1 to Ton3) indicates the current application period during which an electric current is to be applied to the coil Lx within one control cycle of the control signal DRx; Toffx (Toff1 to Toff3) indicates the non-current application period (= Tbase - Tonx) during which no electric current is to be applied to the coil Lx within one control cycle of the control signal DRx. Furthermore, in the present embodiment, the N-channel MOSFET (metal oxide semiconductor FET) is used as the switching element Trx, and an electric current is applied to the coil Lx in the high-side drive mode. The high state or high level of the control signal DRx applied to the switching element Trx corresponds to the voltage (e.g., 20 V) higher than the battery voltage VB (e.g., typically 10 to 14 V); For example, the low state or low level of the control signal DRx corresponds to zero (0) V.

[0039] The following explains a signal output from microcomputer 3 to driver 2 to generate control signals DR1 to DR3. The explanation will be given in detail with reference to the signal for generating control signal DR1. The same applies to the signals for generating other control signals DR2 and DR3.

[0040] Reference is made to the first row from the top in Fig. 1(B). The microcomputer 3 generates and outputs a base signal BA1 having a cycle identical to the actuating cycle Tbase of the actuating signal DR1. The base signal BA1 is in the high state during the peak current application period Tp, starting from the cycle start point of the actuating signal DR1, and then in the state corresponding to the holding signal HD during the holding current application period Th following the peak current application period Tp and ending with the end point of the actuating cycle Tbase.

[0041] Further reference is made to the fourth row in Fig. 1(B). The microcomputer 3 generates and outputs a control key signal DD1, which is a PWM signal having the same cycle as the control cycle Tbase of the control signal DR1 and transitions to the high state at the cycle start point of the control signal DR1.

[0042] In the output driver 2, the signal generation circuit 11, which is provided to correspond to the switching element Tr1, calculates a logical product of the base signal BA1 and the actuating signal DD1 output from the microcomputer 3. The high state of the signal of the logical product of the two signals BA1 and DD1 is converted into the actuating signal DR1 of 20 V (that is, the voltage that can completely switch the switching element Tr1 to the ON state). The actuating signal DR1 is then output to the gate of the switching element Tr1. Accordingly, the actuating signal DR1 is shown in the seventh row in Fig. 1(B).

[0043] In addition, as in the second series of Fig. As shown in Figure 1(B), the microcomputer 3 outputs a base signal BA2 which is identical in waveform to the base signal BA1 and delayed in phase by the peak current application time Tp from the base signal BA1. Further, reference is made to the third row in Fig. 1(B). Microcomputer 3 outputs a base signal BA3 whose waveform is identical to base signal BA1 and whose phase is delayed by twice the peak current duration Tp (i.e., by 2 × Tp) relative to base signal BA1.

[0044] In addition, the fifth row in Fig. 1(B). The microcomputer 3 generates and outputs a control signal DD2 of a PWM signal having a cycle identical to that of the control signal DD1 and delayed in phase by the peak current application time Tp from the control signal DD1. Further, reference is made to the sixth row in Fig. 1(B). The microcomputer 3 generates and outputs a control signal DD3 of a PWM signal having a cycle identical to that of the control signal DD1 and whose phase is delayed by twice the peak current duration Tp (i.e., by 2 × TP) compared to the control signal DD1.

[0045] In the output driver 2, similar signal generation circuits 12, 13 are provided to correspond to the switching elements Tr2, Tr3, as in the signal generation circuit 11. The signal generation circuit 12 generates a control signal DR2 from the base signal BA2 and the control key signal DD2 from the microcomputer 3 and outputs the generated control signal DR2 to the gate of the switching element Tr2. Similarly, the signal generation circuit 13 generates a control signal DR3 from the base signal BA3 and the control key signal DD3 from the microcomputer 3 and outputs the generated control signal DR3 to the gate of the switching element Tr3.

[0046] As described above, of the high duration and low duration of the control signal DDx, the high duration indicates a current application duration Ton (Tonx), during which an electric current is to be applied to the coil Lx; the low duration corresponds to a non-application duration Toff (Toffx), during which no electric current is applied to the coil Lx. The duration during which the control signal DDx is in the high state corresponds to a current application duration during which a current is applied to the coil Lx. Fig. 1(B), the current application duration Ton3, which is the high duration of the control signal DD3, is shorter than the peak current application duration Tp. The control signal DR3 remains in the high state from the cycle start point of one control cycle and then in the low state until the cycle end point of the one control cycle of the control signal DR3.

[0047] The generated control signal DRx is supplied to the gate of the switching element Trx. The electric current is thus applied to the coil Lx of the solenoid valve Vx, and the solenoid valve Vx is driven. Reference is made to Fig. 3(A). That is, the ON state of the switching element Trx continues during the peak current application period Tp from the cycle start point of the control cycle Tbase of the control signal DRx to apply the peak current Ip to the coil Lx. Then, the control signal DRx is switched to the ON state or OFF state according to the holding signal HD during the holding current application period Th during which the control signal DRx is the holding signal HD. Thereby, the holding current Ih is applied to the coil Lx so that it is smaller than the peak current Ip, but allows the valve body to remain at least at the position to which the valve body is moved from the standard position. Note that in the present embodiment, the holding current Ih is actually set to the current value so that it is smaller than the peak current Ip, but allows the valve body to move toward the position at which the operation is terminated.In other words, the holding current application duration Th and the duty cycle of the holding signal HD are set to such values ​​that the holding current Ih is set smaller than the peak value Ip, but allow the coil to be applied with the current sufficient to move the valve body toward the position at which the operation is terminated.

[0048] When the control signal DRx transitions from the hold signal HD to the low state, the current flow to the coil Lx stops. From this point, when the predetermined delay time Tcs elapses, the valve body of the solenoid valve Vx begins to return to the standard position. Therefore, before the valve body begins to return to the standard position or before the valve body has returned to the standard position, the cycle start point of the next cycle of the control signal DRx may transition to the high state. In this case, the valve body can move to the position where the operation is terminated without the solenoid valve Vx carefully returning to the closed state.

[0049] As explained above, the ratio of the current application duration Ton to the actuation cycle Tbase (= Ton / Tbase) is equal to the actuation duty cycle. The opening degree of the solenoid valve Vs can be adjusted by controlling the actuation duty cycle. Note that in the present embodiment, the duty cycle of the actuation duty signal DDx is identical to the actuation duty cycle.

[0050] Next, the processings executed by the microcomputer 3 to output the setting key signals DD1 to DD3 and the base signals BA1 to BA3 will be described with reference to Fig. 2 explained. Fig. 2(A) is a flowchart showing processing by which the microcomputer 3 outputs the setting key signals DD1 to DD3.

[0051] The processing in Fig. 2(A) is executed with respect to each of the setting key signals DD1 to DD3. Here, the processing for outputting the setting key signal DDx from any of the setting key signals DD1 to DD3 is explained. Furthermore, the processing in Fig. 2(A) is executed with respect to each control cycle of the control signal DRx generated based on the control key signal DDx. For example, the processing is repeatedly executed immediately before the cycle start point of a current single cycle.

[0052] It should also be noted that a flowchart or the processing of the flowchart in the present application includes sections (also referred to as steps), which are represented, for example, as S110. Further, each section may be divided into different subsections, while different sections are combined into a single section. Furthermore, each of the thus-configured sections may be referred to as a device, a means, a module, or a processing device, and may be obtained not only as a software section in combination with a hardware device, but also as a hardware section. Furthermore, the software section may be included in a software program, which may be included in a non-transitory computer-readable storage medium as a program product.

[0053] The microcomputer 3 starts processing Fig. 2(A). At S110, the duty cycle (=Ton / Tbase) of the actuating signal DRx to be output at the current cycle is determined. For example, the need for the automatic transmission position shift is decided based on a traveling speed (vehicle speed) of the vehicle or an accelerator pedal operation amount. From the decision results, the target opening of the solenoid valve Vx is decided according to the actuating signal DRx, and the duty cycle required to realize the target opening is determined. Note that since the actuating cycle Tbase is known or fixed, determining the duty cycle is equivalent to determining the current application period Ton or the non-application period Toff.

[0054] At S120, it is judged whether the actuating duty cycle determined at S110 is equal to or greater than a predetermined value Dth. If the actuating duty cycle is equal to the predetermined value Dth, the non-energization period Toff (= Tbase - Ton) determined by the determined actuating duty cycle becomes equal to or less than a predetermined minimum value (i.e., lower limit) Toffmin. The minimum value Toffmin is a value less than the aforementioned delay time Tcs. Therefore, at S120, it is judged whether the non-energization period Toff determined by the actuating duty cycle determined at S110 is equal to or less than the minimum value Toffmin. Further, in the present embodiment, the predetermined value Dth is set to, for example, 95%. In this case, "Tbase = 20 ms." The above minimum value Toffmin is set to 1 ms.

[0055] If it is determined at S120 that the actuating duty cycle is not equal to or greater than the predetermined value Dth (when the negative decision is made), processing proceeds to S140. Conversely, if it is determined at S120 that the actuating duty cycle is equal to or greater than the predetermined value Dth (when the positive decision is made), processing proceeds to S130, where the actuating duty cycle is changed to be set to 100%. This indicates that the current application duration Ton is set to the value identical to the actuating cycle or the actuating duration Tbase. In other words, the non-application duration Toff is set to zero. Processing then proceeds to S140.

[0056] At S140, the determined duty cycle (i.e., the value determined at S110, or 100% as set at S130) is assigned to the PWM circuit in microcomputer 3 as a duty cycle of the PWM signal to output the duty cycle signal DDx. Then, the PWM circuit outputs the PWM signal having the duty cycle Tbase and the duty cycle, which is set at S140 as the duty cycle signal DDx. The output start point of the duty cycle signal DDx is an arrival start point of the duty cycle of the duty cycle signal DRx.

[0057] Thus, the above processing in Fig. 2(B) for each cycle of the control signal DRx; the microcomputer 3 outputs the control duty signal DDx, which is the PWM signal with the same duty cycle as the control duty cycle. If the positive decision is made at S120, the control duty cycle is set to 100% at S130; the control duty signal DDx is constantly in the high state throughout this control cycle Tbase, as shown in Fig. 4(B).

[0058] Note that the PWM circuit is provided to correspond to each of the control signals DD1 to DD3. The timings when the PWM circuits start outputting the control signals DD1 to DD3 are shifted from each other by the peak current duration Tp, as shown in Fig. 1(B).

[0059] Next is Fig. 2(B) is a flowchart illustrating processing in which the microcomputer 3 outputs the base signals BA1 to BA3. The processing in Fig. 2(B) is executed with respect to each of the base signals BA1 to BA3. Here, the processing to output the base signal DDx of each of the base signals BA1 to BA3 is explained. In addition, the processing in Fig. 2(B) at the cycle start point of a control cycle of the control signal DRx, which is generated based on the base signal BAx. Thus, the processing of Fig. 2 with respect to the base signals BA1 to BA3 by shifting them relative to each other by the peak current application time Tp.

[0060] The microcomputer 3 starts processing Fig. 2(B). At S210, a decision is made as to whether the positive decision regarding the control signal DRx of the previous cycle was made at S120. If it is determined that the positive decision regarding the control signal DRx of the previous cycle was not made, processing proceeds to S220.

[0061] At S220, the base signal BAx is caused to remain high during the peak current application period Tp. When the peak current application period Tp expires, processing continues with S240, where the base signal BAx is output in the hold signal HD state until the cycle end point of the single control cycle of the control signal DRx.

[0062] If it is decided at S210 that the negative decision was made at S120 with regard to the control signal DRx of the previous cycle, the base signal BAx is thereby in the Fig. 1(B). In contrast, if it is decided at S210 that the positive decision was made at S120 with respect to the control signal DRx of the previous cycle, processing proceeds to S230. The base signal BAx is output in the hold signal HD state instead of the high state. If the peak current application time Tp elapses, processing proceeds to S240. Then, the base signal BAx is output in the hold signal HD state until one control cycle of the control signal DRx is completed.

[0063] If it is decided that the positive decision was made at S120 with regard to the control signal DRX of the previous cycle, the base signal BAx remains in the state of the hold signal HD during the peak current application period, which begins with the cycle start point of the control cycle of the control signal DRx. As in Fig. As shown in Figure 4(B), the control signal DRx finally remains in the state of the hold signal HD over one control cycle Tbase.

[0064] Next, the action of the above electromagnetic valve driving device 1 will be explained. First, when the negative decision is “NO” at S120 in Fig. 2(A), the actuating duty signal DDx serving as a starting point of the actuating signal DRx of the current cycle is not subjected to S130 where the duty ratio of the actuating duty signal DDx is switched to 100%, while the base signal BAx serving as a starting point of the actuating signal DRx of the next cycle is not subjected to S230 where the base signal BAx is switched to the holding signal HD since the cycle start point of the actuating cycle.

[0065] Therefore, as in Fig. 1 (B), the setting duty signal DDx output from the microcomputer 3 is the PWM signal with the same duty cycle as the setting duty cycle, while the base signal BAx output from the microcomputer 3 also remains in the state of the base signal as shown in Fig. 1(B). Therefore, the control signal DRx applied to the switching element Trx remains in the state of the ordinary waveform shown in Fig. 1(B) and Fig. 3(A).

[0066] Thus, the valve body of the solenoid valve Vx promptly moves toward the operation-termination position during the peak current application period Tp, during which the control signal DRx is in the high state. Then, the valve body even slowly moves toward the operation-termination position or remains at the fixed position during the holding current application period Th, during which the control signal DRx is in the hold signal HD state. Furthermore, the valve body begins to return to the standard position when the control signal DRx switches from the hold signal HD state to the low state.

[0067] In contrast, in S120 in Fig. 2(A) the affirmative decision is made as "YES", the actuating key signal DDx serving as a starting point of the actuating signal DRx of the current cycle is subjected to S130, while the base signal BAx serving as a starting point of the actuating signal DRx of the next actuating cycle is subjected to S230.

[0068] In this case, the setting key signal DDx of the current cycle output from the microcomputer 3 remains in the high state for one setting cycle, as shown in Fig. 4(B). The control signal DRx of the current cycle applied to the switching element Trx remains in the state of the hold signal HD over a range from the end point of the peak current application period Tp to the cycle start point of the next control cycle, as shown within the dot-dash ellipse in Fig. 3(B). In addition, the base signal BAx of the next control cycle from the microcomputer 3 still remains in the state of the hold signal HD during the peak current application period Tp starting from the cycle start point of the next control cycle, as shown in Fig. 4(B). Thus, as within a two-dotted line ellipse in Fig. 3(B), the control signal DRx of the next control cycle is in the state of the hold signal HD instead of in the high state.

[0069] Therefore, the control signal DRx continues to be in the hold signal HD state from the end point of the peak current application period of the current cycle until the end point of the current application period Ton of the next cycle. Therefore, the valve body is maintained at least at the same position even though the control signal DRx of the next cycle does not transition to the high state during the peak current application period.

[0070] Assuming that the actuating duty ratio determined at S110 is equal to or greater than the predetermined value Dth, when S130 and S230 are not executed, the actuating signal DRx and the electric current applied to the coil Lx give the states shown in Fig. 4(A) equal Fig. 10(B) as mentioned above. The non-energization period Toff, during which the control signal DRx of the current cycle remains in the low state, is shorter than the delay period Tcs explained above. The valve body of the solenoid valve Vx does not return toward the standard position until the energization period Ton of the control signal DRx of the next cycle ends.

[0071] To this end, in the electromagnetic valve drive device 1 of the present embodiment, when the actuating duty ratio determined at S110 is equal to or greater than the predetermined value Dth, S130 and S230 are executed. This eliminates the need for the actuating signal DRx of the next cycle to transition to the high state during the peak current application period Tp. This corresponds to the fact that during the peak current application period Tp, the switching element Trx does not remain in the ON state. Thus, the electric current applied to the coil Lx can become low. According to the electromagnetic valve drive device 1 of the present embodiment, useless power consumption can be prevented.

[0072] Will be used at S120 in Fig. 2(A) continuously makes the positive decision (that is, when the actuating duty cycle determined at S110 is equal to or greater than the predetermined value Dth continuously in successive actuating cycles), the actuating signal DRx continues to be in the state of the holding signal HD over the different actuating cycles as shown in Fig. 4(B).

[0073] In addition, at S120, for example, another decision can be made regarding whether the current application duration Ton is equal to or greater than a value satisfying "Toff ≤ Toffmin." Alternatively, another decision regarding whether the non-application duration Toff, which is determined by the actuating duty cycle, is equal to or less than the minimum value Toffmin, can be made directly.

[0074] In contrast, in the present embodiment, the holding current Ih applied to the coil Lx with the holding signal HD is set to a value such that the valve body of the solenoid valve Vx can be moved toward the operation-termination position. Even if the duty cycle is drastically changed from zero or a value close to zero to the predetermined value Dth and the holding current Ih is continued, the valve body of the solenoid valve Vx can be moved toward the operation-termination position, although it takes a longer time.

[0075] Alternatively, the holding current Ih may be set to a minimum value to maintain the position of the valve body of the solenoid valve Vx at the same position. In this case, full opening of the solenoid valve Vx is performed as follows. For example, the solenoid valve Vx is fully opened by gradually increasing the duty cycle within the range of the duty cycle less than the predetermined value Dth; then, the duty cycle is set to the value equal to or greater than the predetermined value Dth, thereby maintaining the solenoid valve Vx in the fully open state.

[0076] Furthermore, in the present embodiment, at S230 of Fig. 2(B) The state of the base signal BAx from the cycle start point of the control cycle (i.e., the state of the control signal DRx from the cycle start point) is the state of the hold signal HD. Compared with the case of switching to a signal having a different cycle and duty cycle from the hold signal HD, the processing for outputting the control signal DRx can be simplified.

[0077] Furthermore, in the present embodiment, the microcomputer 3, the S110 in Fig. 2(A), function as an example of a determining section, a determining device or a determining means; the microcomputer 3, which performs S140 in Fig. 2(A), the microcomputer 3 which includes the PWM circuit, the microcomputer 3 which executes S240 in Fig. 2(B), or the signal generating circuits 11 to 13 in the output driver 2 may function as an example of a control signal output section, a control signal output device, or a control signal output means. The microcomputer 3, which executes S120 in Fig. 2(A) can function as an example of a decision section, a decision device, or a decision means. The microcomputer 3, which executes S130 in Fig. 2(A) and S210, S230 in Fig. 2(B) may function as a signal changing section, a signal changing device, or a signal changing means. Furthermore, in the present embodiment, the hold signal HD may correspond to a hold pulse train signal or a peak-suppressed pulse train signal. Furthermore, the peak current application period Tp may be a predetermined period. <Erste Modifikation>

[0078] Various modifications are explained below. Control for operating the solenoid valve Vx from the fully closed state to the fully open state can be achieved by gradually increasing the duty cycle. Such control can provide an advantage for preventing the valve body from backlashing, that is, the valve body from striking the position where the operation is completed and then returning from it.

[0079] As mentioned in the above section of Fig. 5, in the electromagnetic valve driving device 1 according to the above embodiment, the actual duty cycle becomes 100% when the determined duty cycle is in the control range larger than the predetermined value Dth, in such a control range, the control signal DRx is only in the state of the hold signal HD instead of the high state (see FIG. Fig. 4(B)). Thus, as shown by the solid line in the lower section of Fig. 5, the rate of increase of the valve opening (speed of movement of the valve body) in the solenoid valve Vx is reduced.

[0080] Now the comparison example is shown as a dotted line in the lower section of Fig. 5. Such a comparative example in an electromagnetic valve drive device can be provided as follows. Even if the determined actuating duty ratio is equal to or greater than the predetermined value Dth, the determined actuating duty ratio is directly reflected in the actuating signal DRx, while the state is maintained in the high state during the peak current application period without changing to the state of the holding signal HD. In detail, S120, S130, S210, and S230 are described in Fig. 2 is not applied. Time ta is when the valve opening reaches 100% in the comparative example. Time tb is when the valve opening reaches 100% in the above embodiment. The difference between time ta and time tb indicates an operation response delay of the valve body.

[0081] For this purpose, in order to suppress such an operation response delay, the above embodiment may be modified as follows. First, assume the case where the microcomputer 3 is in Fig. 2(B) makes a "NO" decision in the previous control cycle and then makes a "YES" decision in the current control cycle. In this case, at S230, the base signal BAx is output as a different pulse train signal during the peak current application period Tp instead of the above-mentioned hold signal HD. The different pulse train signal is in the high state with the same duty cycle as that of the hold signal HD, but with a different standard duty cycle α (e.g., 90%) that is greater than that of the hold signal HD.

[0082] Secondly, the case is assumed that the microcomputer 3 at S210 in Fig. 2(B) makes a "YES" decision in the previous control cycle and a "YES" decision in the current control cycle. In this case, at S230, the base signal BAx is output as yet another pulse train signal during the peak current application period Tp. The yet another pulse train signal is in the high state with the same duty cycle as that of the hold signal HD, but with yet another duty cycle that is smaller than the standard duty cycle α of the other pulse train signal output at S230 of the previous cycle. Note that the duty cycle of the yet another pulse train signal is set to be larger than the duty cycle of the hold signal HD.

[0083] This means that the first case is assumed if the determination result at S120 is in Fig. 2(A) changes from the negative decision result (NO) in the previous control cycle to the positive decision result (YES) in the current control cycle. If such a case occurs, the signal is changed during the peak current application period of the control signal DRx of the next control cycle to a first different pulse train signal with a duty cycle of a standard value α greater than the duty cycle of the hold signal HD, as shown in the two-dot chain ellipse in Fig. 6. Then a second case is assumed if the decision result at S120 is in Fig. 2(A) is the positive decision result consecutively in the previous control cycle and the current control cycle after the first case occurs. If such a case occurs, the signal is changed during the peak current application period of the control signal DRx of the next control cycle to the second other pulse train signal, which has a duty cycle greater than that of the hold signal HD but smaller than that of the first other pulse train signal in the current control cycle.

[0084] Therefore, when the decision result at S120 is repeatedly confirmed, the duty cycle of the pulse train signal during the peak current application period of the control signal DRx is gradually decreased from the standard value α, which is larger than the duty cycle of the hold signal HD, at each control cycle of the control signal DRx, to thereby approach the duty cycle of the hold signal HD.

[0085] According to such a configuration of the first modification, the duty ratio is increased to gradually approach 100%; thereby, when the control for causing the solenoid valve Vx to be in the open state is executed, the valve body of the solenoid valve Vx can be moved to the position at which the operation is terminated (fully open position) in a timely manner.

[0086] After the determined actuating duty cycle becomes equal to or greater than the predetermined value Dth, the duty cycle of the pulse train signal in the peak current application period Tp of the actuating signal DRx becomes greater than the duty cycle of the holding signal HD. Ip' indicates Fig. 6, an electric current is applied to the coil Lx of the solenoid valve Vx when the duty cycle of the pulse train signal is the standard value α during the peak current application period Tp of the control signal DRx. The electric current Ip' is smaller than the ordinary peak current Ip, but larger than the holding current Ih.

[0087] Thus, this first modification can provide a solution for improving both the operating response of the valve body and energy saving in a balanced manner. In the first modification, the pulse train signal during the peak current application period of the control signal DRx can be referred to as a pulse train signal with suppressed peaks. Furthermore, the cycle of the pulse train signal during the peak current application period can be different from that of the hold signal HD. If the cycle of the pulse train signal during the peak current application period is identical to that of the hold signal HD, the processing for outputting the control signal DRx can be simplified. <Zweite Modifikation>

[0088] Fig. 7 illustrates the solenoid valve drive device 1 of the above-described embodiment, in which the following is assumed: The duty cycle of the drive signal DR1 of the solenoid valve V1 is determined to be equal to or greater than the predetermined value Dth; the duty cycle of the drive signal DR2 of the solenoid valve V2 is determined to be zero%; and the duty cycle of the drive signal DR3 of the solenoid valve V3 is determined to be less than the predetermined value Dth (e.g., 50%).

[0089] In such a case, the base signal BA1 goes into the state of the hold signal HD instead of the base state which is in Fig. 1(B). The control signal DD1 remains in the high state; thus, the control signal DR1 continues to be in the hold signal HD state. Furthermore, the base signal BA2 is in the base state shown in Fig. 1(B). Since the duty cycle is 0%, the duty cycle signal DD2 remains low. Thus, the control signal DR2 remains low.

[0090] This means that in Fig. 7 regarding the control signal DR1 at S120 of Fig. 2(A) the positive decision is made again. Regarding the control signal DR2, the control duty cycle at S110 is Fig. 2(A) is determined as 0%, that is, the current application time Ton is set to zero.

[0091] According to the above, it is assumed that a drive start request that starts driving the solenoid valve V2 according to the control signal DR2 occurs. Note that the drive start request or control start request is executed by a different control process or control processing by the microcomputer 3.

[0092] The following refers to Fig. 8(A). The control signal DR2 can be output to the solenoid valve V2 in the high state at the cycle start point of the control cycle that comes first after the occurrence of the control start request. Assume the case where the cycle start point of the control signal DR1, which is in the hold signal HD, comes earlier than that of the control signal DR2. In such a case, as shown in Fig. As shown in Figure 8(B), the cycle start point of the control signal DR2 can be advanced to the cycle start point (t5) of the control signal DR1, so that the control signal DR2 can be output in the high state at the cycle start point (t5). Furthermore, the cycle start point of the control signal DR1 can be delayed by the peak current application period Tp.

[0093] That is, in order to advance the cycle start point of the control signal DR2, the cycle start point of the control signal DR2 can be replaced by the cycle start point of the control signal DR1, which remains in the state of the hold signal HD.

[0094] Thus, replacing the starting point can prevent the temporary drop in battery voltage VB, while improving the control start response of the solenoid valve V2 according to the control signal DR2. In detail, compared with the case in Fig.8(A), the drive or positioning of the solenoid valve V2 can be advanced by the peak current application time Tp. Note that the control signal DR1 remains in the pulse train signal state (here, the hold signal HD state). Even if the control signal DR2 is output in the high state at the output cycle start point (t5), the peak current Ip is not applied to both coils L1, L2 of the solenoid valves V1, V2 at the same time, and no disturbance occurs in the control of the solenoid valve V1.

[0095] For example, the solenoid valve for the drive may be different from a solenoid valve for changing an automatic transmission. Furthermore, the number of solenoid valves may be one or a number other than three. Furthermore, the drive form or actuation form of the solenoid valve may be a low-side drive form in which a switching element is arranged downstream of a coil.

[0096] Furthermore, from the functions of the signal generation circuits 11 to 13 that generate the actuating signals DR1 to DR3, functions other than the function of converting the high state to 20 V by the microcomputer 3 can be obtained. Therefore, when the driving form of the electromagnetic valve is the low-side driving form and the switching elements Tr1 to Tr3 can be switched to the ON state using the actuating signal that causes the power source voltage of the microcomputer 3 to be in the high state (for example, 5 V), the actuating signals DR1 to DR3 can be directly output from the microcomputer 3 to the switching elements Tr1 to Tr3.

[0097] It will be obvious to those skilled in the art that various modifications may be made to the above-described embodiments of the present invention. However, the scope of the present invention is determined by the claims.

[0098] The invention can be summarized as follows. An electric current is applied to a coil of a solenoid valve using an actuating signal. Within a current application period of the actuating cycle, a peak current is applied during a peak current application period, and a pulse train signal is applied during a holding current application period. Furthermore, no current is applied from an end point of the current application period to an end point of the actuating period. If a difference obtained by subtracting the current application period from the actuating cycle is not greater than a value, the holding pulse train signal is applied from an end point of the peak current application period to a start point of the next actuating cycle, and further during the peak current application period of the next cycle.

Claims

[1] An electromagnetic valve drive device (1) that drives an electromagnetic valve (Vx) by switching a switching element (Trx) on and off using an actuating signal (DRx) with an actuating cycle of a predetermined actuating duration (Tbase), wherein the switching element (Trx) is arranged in series with a coil (Lx) of the electromagnetic valve (Vx) in a current supply circuit and is configured to supply current to the coil (Lx), the electromagnetic valve drive device (1) comprising: a determination means (3, S110) configured to determine a current application period (Ton) during which a current application to the coil (Lx) is to be carried out within the actuating period (Tbase) of each actuating cycle of successive actuating cycles of the actuating signal (DRx), wherein a non-actuating period (Toff = Tbase - Ton) is defined between an end point of the current application period (Ton) and an end point of the actuating period (Tbase); a control signal output means (3; S140; 3, S240; 11 to 13) configured to output the control signal (DRx) to the switching element (Trx), in an active state for switching on the switching element (Trx) during a peak current application period (Tp), in a hold signal state during a hold current application period (Th), and in a non-active state for switching off the switching element (Trx) during the non-application period (Toff), where the current application duration (Ton) includes (i) the peak current application duration (Tp), which starts with a starting point of the actuating cycle, and (ii) the holding current application duration (Th), which follows the peak current application duration (Tp), the peak current application period (Tp) is a period during which the control signal (DRx) in the active state applies a peak current to the coil (Lx) to enable a valve body of the solenoid valve (Vx) to move from a standard position towards a position at which the operation is terminated, the holding current application duration (Th) is a duration during which the control signal (DRx) in the holding signal state becomes a holding pulse train signal having a predetermined duty cycle in the active state, wherein the holding pulse train signal applies to the coil (Lx) a holding current that is smaller than the peak current but can maintain at least one position to which the valve body is moved from the standard position; a decision means (3, S120) configured to make a decision as to whether or not the non-energization period (Toff) is equal to or less than a predetermined minimum value each time the determination means (3, S110) determines the current application period (Ton) with respect to a current actuation cycle; and a signal shape changing means (3, S130, S210, S230) configured to change the control signal (DRx) when the decision means (3, S120) makes a positive decision regarding the current control cycle such that (i) with respect to the current actuation cycle, by eliminating the non-actuation period (Toff), the determined current actuation period (Ton) is changed to be equal to the predetermined actuation period (Tbase), thereby causing the actuation signal (DRx) to be the sustain pulse train signal from the end point of the peak current actuation period (Tp) to a start point of a next actuation cycle following the current actuation cycle, and (ii) with respect to the next control cycle, the control signal (DRx) is in a peak-suppressed state instead of in the active state to become a peak-suppressed pulse train signal during the peak current duration of the next control cycle, the peak-suppressed pulse train signal in the active state having a duty cycle equal to or greater than the duty cycle of the sustain pulse train signal, wherein the minimum value used by the decision means (3, S120) is predetermined to be less than a delay period (Tcs) ranging from the time when the control signal (DRx) transitions from the hold signal state to the inactive state to the time when the valve body begins to return to the standard position. [2] The electromagnetic valve driving device (1) according to claim 1, wherein the holding pulse train signal applies to the coil (Lx) the holding current which is smaller than the peak current but allows the valve body to move toward the position at which the operation is terminated. [3] The electromagnetic valve driving device (1) according to claim 1 or 2, wherein the peak suppressed pulse train signal has a cycle and a duty ratio identical to the cycle and the duty ratio of the sustain pulse train signal. [4] The solenoid valve driving device (1) according to claim 1 or claim 2, wherein: the waveform changing means (3, S130, S210, S230), in cases where the decision as to whether or not the non-current duration is equal to or less than the minimum value is changed by the decision means (3, S120) from a negative decision in the previous cycle to a positive decision in the current cycle, changes the duty cycle of the peak-suppressed pulse train signal of the next cycle to have a standard value that is greater than the duty cycle of the sustain pulse train signal; and the waveform changing means (3, S130, S210, S230), in cases where the positive decisions that the non-current duration is equal to or less than the minimum value by the decision means (3, S120) are continued in the previous cycle and the current cycle, changes the duty cycle of the peak-suppressed pulse train signal of the next cycle to have a value equal to or greater than the duty cycle of the sustain pulse train signal and less than the duty cycle of the peak-suppressed pulse train signal of the current cycle. [5] Solenoid valve drive device (1) according to one of claims 1 to 4, wherein: the solenoid valve drive device (1) drives a plurality of solenoid valves (Vx), the electromagnetic valve drive device (1) includes, with respect to each of the plurality of electromagnetic valves (Vx), the switching element (Trx), the determination means (3, S110), the control signal output means (3; S140; 3, S240; 11 to 13), the decision means (3, S120), and the signal shape changing means (3, S130, S210, S230); and Starting points of the actuating cycles of the actuating signals (DRx) corresponding to the assigned solenoid valves (Vx) are shifted from one another by a duration which is equal to or greater than the peak current application duration (Tp), so that durations during which the actuating signals (DRx) corresponding to the assigned solenoid valves (Vx) are in the active state do not overlap. [6] Electromagnetic valve drive device (1) according to claim 5, wherein a first condition is defined as a case in which (i) with respect to a first control signal (DR1) from the plurality of control signals (DRx), the decision means (3, S120) repeatedly makes an affirmative decision in successive cycles and at the same time (ii) with respect to a second control signal (DR2) from the plurality of control signals (DRx) which is different from the first control signal (DR1), the determination means (3, S110) determines that the current application duration (Ton) is zero; a second condition is defined as a case where a request that starts driving the solenoid valve (Vx) according to the second control signal (DR2) occurs under the first condition; and if a first starting point (t5) of the control cycle of the first control signal (DR1) comes earlier than a second starting point (t6) of the control cycle of the second control signal (DR2), the second starting point (t6) of the actuating cycle of the second actuating signal (DR2) is brought forward to an advanced starting point (t5) which is identical to the first starting point (t5) of the actuating cycle of the first actuating signal (DR1), so that the second actuating signal (DR2) is started in order to be output in the active state at the advanced starting point (t5) of the actuating cycle.

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