Active vibration isolating support apparatus and method for controlling the same

When a revolution speed of the engine (crankshaft) changes faster or slower, the vibration from the engine is propagated to an occupant in the vehicle, and the occupant may feel a sense of discomfort. For this reason, the present invention provides an active vibration isolating support apparatus and method for controlling the same to suppress the propagation of the vibration from the engine to the vehicle body so that the occupant may feel less sense of discomfort even if the revolution speed of the engine changes.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims benefit of the filing dates of Japanese Patent Applications Nos. 2009-071883 filed on Mar. 24, 2009, and 2009-071921 filed on Mar. 24, 2009 which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an active vibration isolating support apparatus to elastically support an engine in a vehicle body so as to suppress propagation of vibration from the engine to the vehicle body, and a method for controlling the same.

2. Description of the Related Art

Because the vibration in the engine is generated per revolution of a crankshaft, the vibration is generated at a relatively high frequency, single vibration terminates in short time, and a cycle of the vibration is short. For this reason, it has been proposed that a control to suppress the propagation of the vibration is performed using a time during which three vibrations are generated (for example, see JP 2005-003050 A). If times during which three vibrations are generated are denoted as a first real cycle, a second real cycle, and a third real cycle in sequence, the vibration is measured in the first real cycle, a target current of a driving current supplied to the active vibration isolating support apparatus is calculated in the second real cycle, and the driving current is supplied to the active vibration isolating support apparatus in the third real cycle.

However, when a revolution speed of the engine (crankshaft) changes faster or slower, the vibration from the engine is propagated to an occupant in the vehicle, and the occupant may feel a sense of discomfort.

For this reason, an object of the present invention is to provide an active vibration isolating support apparatus and method for controlling the same to suppress the propagation of the vibration from the engine to the vehicle body so that the occupant may feel less sense of discomfort even if the revolution speed of the engine changes.

SUMMARY OF THE INVENTION

The present invention provides an active vibration isolating support apparatus, including: a control unit to measure a crank pulse based on revolution of an engine, to calculate a target current value supplied to an actuator for isolating vibration in a next second vibration cycle using data of the crank pulse which belongs to a first vibration cycle of a cycle of vibration of the engine, and to control the actuator using the calculated target current value in a next third vibration cycle,

in which the control unitcalculates a length of the first vibration cycle,defines a crank pulse interval of the crank pulse which belong to the first vibration cycle at a predetermined position of the first vibration cycle as a first pulse interval,defines a crank pulse interval of the crank pulse which belong to the second vibration cycle at a predetermined position of the second vibration cycle which is set corresponding to the predetermined position of the first vibration cycle as a second pulse interval,calculates a length of the second vibration cycle using the first pulse interval, the second pulse interval, and the length of the first vibration cycle,calculates a length of the third vibration cycle using the length of the first vibration cycle, and the length of the second vibration cycle, andcalculates the target current value supplied to the actuator using the calculated length of the third vibration cycle in the second vibration cycle.

When the revolution speed of the engine changes (for example, changes faster), the cycle of the vibration generated in the engine becomes shorter in the order of the first vibration cycle (the first real cycle), the next second vibration cycle (the second real cycle), and the next third vibration cycle (the third real cycle). In the case where the vibration is measured by reading a first generating interval (the first pulse interval) of the crank pulse over the first real cycle in the first real cycle, where the target current of the driving current supplied to the active vibration isolating support apparatus is calculated in the second real cycle so as to correspond to the first real cycle, and where the driving current is supplied to the active vibration isolating support apparatus in the third real cycle so as to realize the target current corresponding to the first real cycle, it is thought that suppression of the propagation of the vibration is not enough because the driving current for the first real cycle whose length differs from that of the third real cycle is supplied in the third real cycle.

In the present invention, a pulse based on the revolution of the engine is measured, first to third vibration cycles are set, and the driving current of the actuator in the third vibration cycle is calculated from the lengths of the first and second vibration cycles and pulse data. For this reason, it possible to supply the driving current which is more appropriate to the third vibration cycle, and to suppress the propagation of the vibration of the engine enough.

Also, in the present invention, the length of the third vibration cycle can be surely calculated in the second vibration cycle. Although the first generating interval (the first pulse interval) at a predetermined position which is a beginning, etc., of the first vibration cycle (the first real cycle), the second generating interval (the second pulse interval) at a predetermined position which is a beginning, etc., of the second vibration cycle (the second real cycle), and the length of the first vibration cycle (the first real cycle) are used for calculation of the length of the third vibration cycle, the first generating interval and the first calculation cycle at the predetermined position (beginning, etc.) of the first real cycle are obtained based on the data read at the first real cycle, and the second generating interval at the predetermined position (beginning, etc.) of the second real cycle is obtained at the predetermined position (beginning, etc.) of the second real cycle. For this reason, because third calculation cycle can be calculated based on the data obtained by the predetermined position (beginning, etc.) of the second real cycle at the latest, the length of the third vibration cycle (the third calculation cycle) can be surely calculated in the second real cycle. Conversely, back-calculating a time necessary for calculating the length of the third vibration cycle (the third calculation cycle), etc., the predetermined position may be set not only at the beginning but also at a middle and an end of the second real cycle as long as the length of the third vibration cycle (the third calculation cycle), etc. can be calculated in the second real cycle, and a predetermined position set for the first real cycle is set at the beginning, middle, or end corresponding to the above.

Also, the present invention provides an active vibration isolating support apparatus, including: a control unit to measure a crank pulse based on revolution of an engine, to calculate a target current value supplied to an actuator for isolating vibration in a next second vibration cycle using data of the crank pulse which belongs to a first vibration cycle of a cycle of vibration of the engine, and to control the actuator using the calculated target current value in a next third vibration cycle,

in which the control unitcalculates a length of the first vibration cycle,defines a crank pulse interval of the crank pulse which belong to the first vibration cycle at a predetermined position of the first vibration cycle as a first pulse interval,defines a crank pulse interval of the crank pulse which belong to the second vibration cycle at a predetermined position of the second vibration cycle which is set corresponding to the predetermined position of the first vibration cycle as a second pulse interval,calculates a length of the second vibration cycle using the first pulse interval, the second pulse interval, and the length of the first vibration cycle, andcalculates the target current value supplied to the actuator using the calculated length of the second vibration cycle in the second vibration cycle.

When the revolution speed of the engine changes (for example, changes faster), the cycle of the vibration generated in the engine becomes shorter in the order of the first vibration cycle (the first real cycle), the next second vibration cycle (the second real cycle), and the next third vibration cycle (the third real cycle). In the case where the vibration is measured by reading a first generating interval (the first pulse interval) of the crank pulse over the first real cycle in the first real cycle, where the target current of the driving current supplied to the active vibration isolating support apparatus is calculated in the second real cycle so as to correspond to the first real cycle, and where the driving current is supplied to the active vibration isolating support apparatus in the third real cycle so as to realize the target current corresponding to the first real cycle, it is thought that suppression of the propagation of the vibration is not enough because the driving current for the first real cycle whose length differs from that of the third real cycle is supplied in the third real cycle.

In the present invention, the length of the second vibration cycle is calculated, and the target current is normalized by the length of the second vibration cycle. Because a driving current for the second real cycle (the second calculation cycle) whose value is not separate from that for the first real cycle is supplied for the third real cycle, deviation in cycle becomes small, and the propagation of the vibration of the engine can be suppressed enough.

Also, in the present invention, the length of the second vibration cycle can be surely calculated in the second vibration cycle. Although the first generating interval (the first pulse interval) at a predetermined position which is a beginning, etc., of the first vibration cycle (the first real cycle), the second generating interval (the second pulse interval) at a predetermined position which is a beginning, etc., of the second vibration cycle (the second real cycle) which is set corresponding to the predetermined position of the first vibration cycle, and the length of the first vibration cycle (the first real cycle) are used for calculation of the length of the second vibration cycle, the first generating interval and the first calculation cycle at the predetermined position (beginning, etc.) of the first real cycle are obtained based on the data read at the first real cycle, and the second generating interval at the predetermined position (beginning, etc.) of the second real cycle is obtained at the predetermined position (beginning, etc.) of the second real cycle. For this reason, because second calculation cycle can be calculated based on the data obtained by the predetermined position (beginning, etc.) of the second real cycle at the latest, the length of the second vibration cycle (the second calculation cycle) can be surely calculated in the second real cycle. Conversely, back-calculating a time necessary for calculating the length of the second vibration cycle (the second calculation cycle), etc., the predetermined position may be set not only at the beginning but also at a middle and an end of the second real cycle as long as the length of the second vibration cycle (the second calculation cycle), etc. can be calculated in the second real cycle, and a predetermined position set for the first real cycle is set at the beginning, middle, or end corresponding to the above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Next, referring toFIGS. 1-8, first and second embodiments of the present invention will be explained in detail. In addition, same reference numbers are used to denote the same components inFIGS. 1-8, and their repeated explanations are omitted.

First Embodiment

As shown inFIG. 1, a V-type six-cylinder engine2is mounted at a front portion of a vehicle V. To the engine2, a transmission3is connected. A direction in which the transmission3is connected to the engine2is an axial direction of a crankshaft (not shown). Therefore, the engine2is so-called side-ways mounted in the vehicle V so that the axial direction of the crankshaft (not shown) coincides with a direction transverse to a body of the vehicle V.

Two active vibration isolating support apparatuses1are disposed at front and rear portions under the engine2along the front-rear direction. Because the vibration of the engine2is generated associated with the revolution of the crankshaft, a direction of an amplitude of the vibration coincides with a direction of a plane surface whose normal is a revolution axis of the crankshaft (i.e., a front-rear and up-down direction inFIG. 1). A pair of the active vibration isolating support apparatuses1are disposed at a front end and a rear end of the engine2along the front-rear direction so that such a force caused by the vibration acts on the direction of the plane surface. One active vibration isolating support apparatus1ais disposed at the front end under the engine2, and the other active vibration isolating support apparatus1bis disposed at the rear end under the engine2.

FIG. 2is a block diagram of a vehicle V provided with the active vibration isolating support apparatuses1(1a,1b) in accordance with a first embodiment of the present invention. Also, the active vibration isolating support apparatuses1(1a,1b) are provided with a control unit4. Two active vibration isolating support apparatuses1(1a,1b) elastically support the engine2to a vehicle body frame8. Each of the two active vibration isolating support apparatuses1(1a,1b) has an actuator9, and a driving current output from the control unit4drives the actuator9to extend and contract, thereby driving the active vibration isolating support apparatuses1(1a,1b) to extend and contract. When the engine vibrates, a space between the engine2and the vehicle body frame8changes. The active vibration isolating support apparatuses1(1a,1b) are driven to extend and contract to this amount of change, and the active vibration isolating support apparatuses1(1a,1b) can suppress propagation of the vibration from the engine2to the vehicle body frame8.

A engine control unit5controls the engine2to start and stop the revolution, and to increase and decrease the revolution speed.

The engine2generates a crank pulse associated with the revolution of the engine2(i.e., the revolution of the crankshaft). A crank pulse sensor7detects the crank pulse, and send it to the control unit4. The crank pulse is output per a predetermined crank angle. For example, the crank pulse sensor7detects the crank pulse 60 times per revolution of the crankshaft, that is, once every 6 degrees of crank angle.

The engine2revolves the crankshaft by vertical motion of pistons in a plurality of cylinders (e.g., six-cylinder). Also, the engine2is provided with TDC pulse sensors6for every cylinder so as to detect a Top Dead Center (TDC) when the piston moves up. The TDC pulse sensor6detects the TDC pulse which is generated when the piston arrives at the TDC in every cylinder. If the engine2is six-cylinder, the TDC pulse sensor6detects the TDC pulse 6 times per 2 revolutions of the crankshaft, that is, once every 120 degrees of crank angle. The TDC pulse sensor6detects the TDC pulse, and sends it to the control unit4.

If the crank pulse is output once every 6 degrees of crank angle and the TDC pulse is output once every 120 degrees of crank angle, the crank pulses are output and detected 20 times per TDC pulse, that is, between the TDC pulses constantly.

FIG. 3is a flowchart of a method for controlling the active vibration isolating support apparatus1in accordance with the first embodiment of the present invention using the control unit4.

First, in step S1, the control unit4receives the TDC pulse which is output per vibration cycle of the engine2, and the crank (CRK) pulse which is output per predetermined crank angle (6 degrees). As shown inFIGS. 4A and 4B, although the TDC pulse is received 4 times, the number of the CRK pulses which are received between the TDC pulses are 20 times, that is constant. Because receiving intervals of the TDC pulse and the CRK pulse become narrower as time t elapses, it is found that the revolution speed of the engine2is increasing.

Because the vibration of the engine2is caused by vertical motion of piston in every cylinder mainly, the vibration of the engine2is synchronized with the TDC pulse which is synchronized with the vertical motion of the piston. For this reason, the vibration cycle of the engine2is a generating or receiving interval of the TDC pulse. A first real cycle T01of the vibration of the engine2is started at the time of receiving the first TDC pulse, and is ended by receiving a second TDC pulse. Likewise, a second real cycle T02of the vibration of the engine2is started at the same time, the first real cycle T01is ended, and the second real cycle T02is ended by receiving a third TDC pulse. Likewise, a third real cycle T03of the vibration of the engine2is started at the same time, the second real cycle T02is ended, and the third real cycle T03is ended by receiving a fourth TDC pulse.

In step S2, the control unit4sequentially reads and stores first generating intervals Δt11, Δt12, . . . , Δt1nwhich are CRK pulse intervals between all of the CRK pulses over the first real cycle T01of the vibration of the engine.

In step S3, the control unit4receives the TDC pulse which is the start of the second real cycle T02of the vibration of the engine, and the crank pulse which is output at the beginning (corresponding to the predetermined position) of the second real cycle T02.

In step S4, the control unit4reads and stores the second generating interval Δt21which is a CRK pulse interval between CRK pulses at the beginning (corresponding to the predetermined position) of the second real cycle T02of the vibration of the engine. In addition, the second generating interval is not limited to the second generating interval Δt21, for example, may be a second generating interval Δt22next to the second generating interval Δt21, and may be a sum of a plurality of second generating intervals (Δt21+Δt22). In this case, in step S6, the first generating interval Δt11at the beginning (corresponding to the predetermined position) in the first calculation cycle T11is changed corresponding to the second generating interval which is the CRK pulse interval between CRK pulses at the beginning (corresponding to the predetermined position) in the second real cycle T02. For example, the first generating interval Δt12at the beginning in the first calculation cycle T11is corresponded to the second generating interval Δt22which is the CRK pulse interval between CRK pulses at the beginning in the second real cycle T02, and a ratio K is calculated by K=T11/Δt12. A sum (Δt11Δt12) of the first generating interval at the beginning in the first calculation cycle T11is corresponded to a sum (Δt21+Δt22) of the second generating interval which is the CRK pulse interval between CRK pulses at the beginning in the second real cycle T02, and the ratio K is obtained by K=T11/(Δt11+Δt12).

In step S5, the control unit4calculates the first calculation cycle T11as a sum of accumulated all of the first generating intervals Δt11, Δt12, . . . , Δt1nover the first real cycle T01. The first calculation cycle T11corresponds to a calculated value of the first real cycle T01. Also, by calculating the first calculation cycle T11, it is possible to grasp the first calculation cycle T11as a time-axis O1whose origin is the start of the first real cycle T01, and calculation is performed for the time on the time-axis O1in steps S6and S7. In addition, steps S5and S4may be performed at the same time.

In step S6, the control unit4calculates the ratio K (=T11/Δt11) between the first calculation cycle T11and the first generating interval Δt11at the beginning (corresponding to the predetermined position) in the first calculation cycle T11. In addition, steps S6and step S4may be performed at the same time. For example, assume that the number of the CRK pulse received between TDC pulses is 20. If the engine2revolves at a constant speed, the ratio K is equal to 20 (K=20), if the engine2accelerates, the ratio K is less than 20 (K<20), and if the engine2decelerates, the ratio K is greater than 20 (K>20).

In step S7, the control unit4calculates an estimated vibration of the engine2corresponding to the first calculation cycle T11, and a target current from the estimated vibration. Concretely, first, the control unit4divides the predetermined crank angle (6 degrees) by the first generating intervals Δt11, Δt12, . . . , Δt1nfor every first generating intervals Δt11, Δt12, . . . , Δt1nso as to calculate crank angular velocities ω. Next, the control unit4differentiates the crank angular velocities ω with respect to time for every first generating intervals Δt11, A t12, . . . , Δt1nso as to calculate crank angular accelerations dω/dt. Next, the control unit4calculates torques Tq for every first generating intervals Δt11, A t12, . . . , Δt1nby Tq=I*dω/dt where I is a moment of inertia around the crankshaft of the engine2. If the crankshaft revolves at a constant angular velocity ω, the torque Tq becomes 0 (zero). However, the angular velocity ω is increased by acceleration of the piston in an expansion process, the angular velocity ω is decreased by deceleration of the piston in the compression process, and the crank angular acceleration dω/dt is generated by increasing/decreasing the revolution speed of the engine2. Therefore, the torque Tq which is proportional to a crank angular acceleration dω/dt composed of the above is generated.

Next, the control unit4calculates amplitudes of the vibration of the engine2for every first generating intervals Δt11, Δt12, . . . , Δt1nbased on the torque Tq. Next, the control unit4calculates lengths for which the active vibration isolating support apparatus1extends and contracts for every first generating intervals Δt11, Δt12, . . . , Δt1nbased on the amplitudes of the vibration of the engine2. Next, the control unit4calculates and determines (a duty waveform of) a target current supplied to the actuator9of the active vibration isolating support apparatus1so as to realize the above lengths for every first generating intervals Δt11, Δt12, . . . , Δt1nas shown by a solid line inFIG. 5A. The target current shown by the solid line inFIG. 5Ais thought to be calculated for the time-axis O1of the first calculation cycle T11, where the cycle is defined by the first calculation cycle T11.

In step S8, the control unit4calculates the second calculation cycle T12(=Δt21*K) from the second generating interval Δt21at the beginning (corresponding to the predetermined position) in the second real cycle T02and the ratio K. The second calculation cycle T12corresponds to a calculated value in the second real cycle T02. Also, by calculating the second calculation cycle T12, it is possible to grasp the second calculation cycle T12as a time-axis O2whose origin is the start of the second real cycle T02. In addition, although the second calculation cycle T12is calculated using the ratio K, it can be substantially calculated by T12=Δt21/Δt11*T11. Because it is thought that the ratio between the first generating interval Δt11at the beginning (corresponding to the predetermined position) in the first real cycle T01and the second generating interval Δt21at the beginning (corresponding to the predetermined position) in the second real cycle T02is approximately equal to the ratio between the first calculation cycle T11and the second calculation cycle T12. Also, the second calculation cycle T12may be calculated using T12=Δt21/Δt11*T11in step S8without calculating the ratio K in step S6.

In step S9, the control unit4calculates a target current corresponding to the second calculation cycle T12shown by a dotted line inFIG. 5Afrom the target current (shown by the solid line inFIG. 5A) corresponding to the first calculation cycle T11, and the second calculation cycle T12. The target current shown by the dotted line inFIG. 5A, that is, a target current shown inFIG. 5Bis thought to be calculated for the time-axis O2of the second calculation cycle T12, where the cycle is defined by the second calculation cycle T12. Also, it can be thought that the target current which is normalized so as to correspond to the first calculation cycle T11is re-normalized so as to correspond to the second calculation cycle T12.

In step S10, the control unit4receives a TDC pulse which is a start of the third real cycle T03of the vibration of the engine.

In step S11, as shown inFIGS. 4C and 5C, the control unit4outputs a driving current so as to coincide with a (normalized) target current corresponding to the second calculation cycle T12in the third real cycle T03and subsequent cycle of the vibration of the engine next to the second real cycle T02. That is, the driving current is normalized corresponding to the second calculation cycle T12. Because a driving current for the second real cycle T02(the second calculation cycle T12) whose value is not separate from that for the first real cycle T01(the first calculation cycle T11) is supplied for the third real cycle T03, deviation in cycle becomes small, the propagation of the vibration of the engine can be suppressed enough, and the occupant may feel less sense of discomfort.

Second Embodiment

In a second embodiment, the active vibration isolating support apparatus1of the first embodiment shown inFIGS. 1 and 2can be used.FIG. 6is a flowchart of a method for controlling the active vibration isolating support apparatus1in accordance with the second embodiment of the present invention using the control unit4(seeFIG. 2) of the active vibration isolating support apparatus1of the first embodiment.

First, steps S1-S8can be performed like the first embodiment.

In step S12, the control unit4calculates a cycle change rate R (=T12/T11) which is a ratio between the second calculation cycle T12and the first calculation cycle T11. In addition, the cycle change rate R may be calculated using R=Δt21/Δt11. In this case, step S12is performed before step S8, and the second calculation cycle T12can be calculated using T12=R*T11in step S8.

In step S13, the control unit4calculates a third calculation cycle T13(=R*T13) from the cycle change rate R and the second calculation cycle T12. The third calculation cycle T13corresponds to a calculated value (measured value) of the third real cycle T03. Also, as shown inFIG. 7, by calculating the third calculation cycle T13, is possible to grasp the third calculation cycle T13as a time-axis O3whose origin is the start of the third real cycle T03. In addition, although the third calculation cycle T13is calculated using the second calculation cycle T12, it can be substantially calculated by T13=(Δt21/Δt11)2*T11=R2*T11. Because it is thought that the ratio between the first generating interval Δt11at the beginning (corresponding to the predetermined position) in the first real cycle T01and the second generating interval Δt21at the beginning (corresponding to the predetermined position) in the second real cycle T02is approximately equal to the ratio between the first calculation cycle T11and the second calculation cycle T12. Also, because it is thought that the ratio between the first calculation cycle T11and the second calculation cycle T12is approximately equal to the ratio between the second calculation cycle T12and the third calculation cycle T13. Also, the third calculation cycle T13may be calculated using T13=(Δt21/Δt11)2*T11in step S10without calculating the second calculation cycle T12in steps S6and S8. Equation T13=(Δt21/Δt11)2*T11is obtained by substituting the above equations. Because the second calculation cycle T12, etc. are removed from this equation, it seems that the second calculation cycle T12is not calculated. However, the second calculation cycle T12may be calculated indirectly in a calculating process using this equation, and it is self-evident that a product does not change if the sequence of multiplication is changed. Therefore, if the second calculation cycle T12is not calculated in the calculating process, the result is substantially equivalent to that where the second calculation cycle T12is calculated in the calculating process.

In step S14, the control unit4calculates a target current corresponding to the third calculation cycle T13shown by a dotted line inFIG. 8Afrom the target current (shown by the solid line inFIG. 8A) corresponding to the first calculation cycle T11, and the third calculation cycle T13. The target current shown by the dotted line inFIG. 8A, that is, a target current shown inFIG. 8Bis thought to be calculated for the time-axis O3of the third calculation cycle T13, where the cycle is defined by the third calculation cycle T13. Also, it can be thought that the target current which is normalized so as to correspond to the first calculation cycle T11is re-normalized so as to correspond to the third calculation cycle T13.

In step S15, the control unit4receives a TDC pulse which is a start of the third real cycle T03of the vibration of the engine.

In step S16, as shown inFIGS. 7C and 8C, the control unit4outputs a driving current so as to coincide with a (normalized) target current corresponding to the third calculation cycle T13in the third real cycle T03and subsequent cycle of the vibration of the engine next to the third real cycle T02. That is, the driving current is normalized corresponding to the third calculation cycle T13. Because a driving current which is normalized by the third calculation cycle T13which approximately coincides with the third real cycle T03, deviation in cycle becomes small, the propagation of the vibration of the engine can be suppressed enough, and the occupant may feel less sense of discomfort.