JP4059220B2 - Liquid supply device - Google Patents

Description

  The present invention relates to an apparatus for supplying a liquid, and more particularly, to a liquid supply apparatus for preventing deterioration of filter performance.

  Conventionally, mechanical oil is supplied to an engine or an automatic transmission by a mechanical oil pump that discharges hydraulic oil using a driving force of an engine mounted on a vehicle. Therefore, the engine does not stop during traveling, so that a predetermined hydraulic pressure can be maintained.

  However, for example, in an economy running vehicle (hereinafter referred to as an “eco-run vehicle”) or a hybrid vehicle in which the engine may stop while traveling, a mechanical oil pump cannot maintain a predetermined oil pressure while the engine is stopped. For this reason, when the engine is restarted, the hydraulic pressure in the engine and the automatic transmission is not sufficiently ensured. Therefore, an electric oil pump that is electrically driven to supply hydraulic pressure to the engine and the automatic transmission is separately provided. When the engine is stopped, an electric oil pump is operated instead of a mechanical oil pump to generate hydraulic pressure, ensuring the hydraulic pressure in the engine and the automatic transmission, and a good restart can be performed.

  Japanese Patent Application Laid-Open No. 11-287316 (Patent Document 1) discloses a hydraulic pressure supply device that activates an electric oil pump with a small sensorless control electric motor with good response. This hydraulic pressure supply device is a hydraulic pressure supply device including a main oil pump and an electric oil pump driven by an electric motor. The hydraulic pressure supply device operates the electric oil pump as necessary to supply hydraulic pressure to the discharge oil passage of the main oil pump while preventing a backflow by a check valve. The hydraulic pressure supply device reduces a load applied to the electric oil pump until the rotation of the electric motor that drives the electric oil pump reaches a predetermined number of rotations when the electric oil pump is started.

According to the hydraulic pressure supply device disclosed in Patent Document 1, when the electric oil pump is started, the load applied to the electric oil pump is reduced, so that the load until the rotation of the electric motor that drives the electric oil pump reaches a predetermined number of rotations. Can be reduced. Therefore, even an electric motor having a small capacity can be started up to a rotational speed at which the magnetic pole position can be detected quickly. And reliable sensorless start-up becomes possible. In addition, the start response of the electric motor can be accelerated.
JP-A-11-287316

  However, in a vehicle having a mechanical oil pump and an electric oil pump, an oil filter for filtering foreign matter such as iron powder flowing in the oil passage is provided, and the oil filter is clogged by the adsorbed foreign matter. There is a problem of causing. In particular, the oil flowing in the oil passage provided in the engine includes foreign matters such as combustion products such as carbon as the engine burns in addition to the iron powder. If a relatively large foreign substance among such foreign substances adheres to the oil filter, the oil filter may be clogged. When the oil filter is clogged, the performance and life of the filter are degraded. In the electric oil pump in Patent Document 1, since it is not assumed that the performance of the filter is deteriorated due to foreign matter, the above-described problem may occur.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a liquid supply apparatus that can prevent a decrease in the performance of an oil filter.

  A liquid supply apparatus according to a first aspect of the present invention is a first supply means for supplying liquid to the liquid passage by rotation of the engine, and a second for supplying liquid to the liquid passage by receiving power supply. Supply means, a first filter provided on the second supply means side of the liquid passage between the first supply means and the second supply means, the first supply means and the second supply Control for controlling the second supply means so as to switch the liquid supply direction by the second filter provided on the first supply means side of the liquid passage between the first supply means and the second supply means Means.

  According to the first invention, the liquid supply device includes a first supply means (for example, an oil pump in which an impeller, a vane, and a gear are rotated by the engine: A mechanical oil pump) and second supply means for receiving liquid and supplying liquid to the liquid passage (for example, an oil pump in which an impeller, vane, or gear is rotated by a motor: Hereinafter, the first filter provided on the electric oil pump side and the second filter provided on the mechanical oil pump side of the liquid passage between the electric oil pump and the electric oil pump. And a control means for controlling the electric oil pump so as to switch the liquid supply direction. For example, a mechanical oil pump supplies liquid to the first filter without passing through the second filter. The second filter is provided at a position downstream of the first filter when the supply direction by the electric oil pump is switched. Thereby, when the supply direction by the electric oil pump is switched in accordance with the stop of the engine, a liquid flow from the first filter to the second filter can be formed. At this time, the foreign matter adhering to the first filter can be moved to the second filter by the flow of the liquid. Therefore, the foreign matter adhering to the first filter can be held by the second filter, so that it is possible to prevent the performance and the performance of the first filter from being deteriorated due to clogging of the foreign matter or the like. it can. Therefore, it is possible to provide a liquid supply apparatus that can prevent a decrease in performance such as the capacity and life of the filter.

  In the liquid supply apparatus according to the second invention, in addition to the configuration of the first invention, the second filter is provided in the liquid passage when the liquid supply direction is switched by the second supply means. There is further provided switching means for switching the passage so as to be positioned downstream of the filter.

  According to the second invention, when the liquid supply direction is switched by the second supply means (for example, an electric oil pump) in the liquid passage, the second filter is located downstream of the first filter. Switching means for switching the path is provided. Thereby, when the supply direction is switched by the electric oil pump, the foreign matter adhering to the first filter can be moved to the second filter. Therefore, since the foreign matter adhering to the first filter can be held by the second filter, it is possible to prevent the performance of the first filter and the performance such as the lifetime from being deteriorated due to clogging of the foreign matter or the like. it can.

  In the liquid supply apparatus according to the third invention, in addition to the structure of the second invention, the switching means is a relief valve or a check valve provided between the first supply means and the second supply means. is there.

  According to the third invention, the switching means is a relief valve provided between the first supply means (for example, a mechanical oil pump) and the second supply means (for example, an electric oil pump) or the reverse. It is a stop valve. When the liquid supply direction is switched by the electric oil pump, a relief valve or a check valve is provided in combination so that the second filter is positioned downstream of the first filter. The adhered foreign matter can be moved to the second filter.

  In the liquid supply apparatus according to the fourth aspect of the invention, in addition to the configuration of any one of the first to third aspects, the control means waits until a predetermined time elapses according to the engine stop instruction. And means for controlling the second supply means to switch the supply direction.

  According to the fourth invention, the control means controls the second supply means (for example, an electric oil pump) so as to switch the supply direction until a predetermined time elapses in response to an instruction to stop the engine. To do. By switching the liquid supply direction until a predetermined time that does not affect the engine start has elapsed, the delay in the rise of hydraulic pressure at the start of the engine due to the liquid leakage in the liquid passage is prevented. Can do.

  The liquid supply apparatus according to a fifth aspect of the invention further includes a detecting means for detecting the flow rate of the liquid flowing in the liquid passage in addition to the configuration of any one of the first to fourth aspects of the invention. The control means includes means for controlling the second supply means so as to switch the supply direction in response to an instruction to stop the engine when the flow rate detected by the detection means is equal to or less than a predetermined amount.

  According to the fifth invention, the control means is configured to switch the supply direction according to the engine stop instruction when the flow rate of the liquid flowing through the liquid passage detected by the detection means is equal to or less than a predetermined amount. Supply means (for example, an electric oil pump) is controlled. When the flow rate detected by the detection means is equal to or less than a predetermined amount, it is determined that the performance of the first filter is degraded due to clogging. Then, by controlling the electric oil pump so as to switch the supply direction in accordance with the engine stop instruction, the foreign matter adhering to the first filter is removed in accordance with the deterioration of the first filter. Can be moved to the filter. Therefore, the foreign matter adhering to the first filter can be held by the second filter, so that it is possible to prevent the performance and the performance of the first filter from being deteriorated due to clogging of the foreign matter or the like. it can.

  In addition to the configuration of any one of the first to fifth inventions, the liquid supply device according to the sixth aspect of the invention is configured such that when the supply direction is switched by the second supply means, the second supply means changes the first supply means. It further includes a liquid passage that forms a liquid flow upstream.

  According to the sixth aspect of the present invention, when the supply direction is switched by the second supply means (for example, an electric oil pump), the second supply means (for example, a mechanical oil pump) upstream from the second filter. A liquid flow to the side (eg oil pan) can be formed. Thereby, the liquid filtered with the 2nd filter can be returned to an oil pan.

  In addition to the configuration of any one of the first to fifth inventions, the liquid supply device according to the seventh invention is changed from the second filter to the second supply means when the supply direction is switched by the second supply means. And a liquid passage for forming a liquid flow.

  According to the seventh invention, when the supply direction is switched by the second supply means (for example, an electric oil pump), a liquid flow can be formed from the second filter to the electric oil pump. . Thereby, the liquid can be circulated from the first filter to the electric oil pump through the second filter.

  In the liquid supply apparatus according to the eighth invention, in addition to the configuration of any one of the first to seventh inventions, the second filter is a coarser filter than the first filter.

  According to the eighth invention, by making the second filter coarser than the first filter, it is possible to move relatively large foreign matter attached to the first filter to the second filter. By specializing the second filter for adsorption of relatively large foreign matters, it is possible to prevent the performance of the second filter, such as the capacity and life of the filter, from deteriorating earlier than the first filter.

  A liquid supply apparatus according to a ninth invention is an apparatus for supplying a liquid to an engine in addition to the configuration of any one of the first to eighth inventions.

  According to the ninth aspect of the present invention, liquid is supplied to the engine by the liquid supply device, so that liquid foreign matters (for example, iron powder and combustion products) flowing in the liquid passage provided in the engine are removed by the first filter. Can be removed. The control means can move the foreign matter adhering to the first filter to the second filter in response to the engine stop instruction. Therefore, the foreign matter adhering to the first filter can be held by the second filter, so that it is possible to prevent the performance and the performance of the first filter from being deteriorated due to clogging of the foreign matter or the like. it can.

  A liquid supply apparatus according to a tenth aspect of the invention is an apparatus that supplies liquid to an automatic transmission in addition to the configuration of any one of the first to eighth aspects of the invention.

  According to the tenth aspect of the invention, the liquid is supplied to the automatic transmission by the liquid supply device, so that the liquid foreign matter (for example, iron powder) flowing through the liquid passage provided in the automatic transmission is removed by the first filter. can do. The control means can move the foreign matter adhering to the first filter to the second filter in response to the engine stop instruction. Therefore, the foreign matter adhering to the first filter can be held by the second filter, so that it is possible to prevent the performance and the performance of the first filter from being deteriorated due to clogging of the foreign matter or the like. it can.

  Hereinafter, a liquid supply apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated. In addition, although the liquid supply apparatus which concerns on this Embodiment supplies a liquid to the liquid channel | path provided in an engine, it is not limited to this. The liquid supply device may supply liquid to a liquid passage provided in the automatic transmission. In addition, although the liquid which concerns on this Embodiment demonstrates as oils, such as machine oil, it is not limited to this in particular. For example, the liquid may be cooling water.

<First Embodiment>
As shown in FIG. 1, the liquid supply apparatus according to the present embodiment includes an oil pump 100 and an electric oil pump 110.

  The oil pump 100 is an oil pump that discharges oil into an oil passage using a driving force of an engine mounted on a vehicle. Although not particularly limited, for example, the oil pump 100 is an oil pump in which an impeller, a vane, or a gear is rotated by an engine. On the other hand, the electric oil pump 110 is an oil pump that receives supply of electric power from a battery (not shown) mounted on the vehicle and supplies oil to the oil passage by an electric motor (not shown). The electric oil pump 110 is an oil pump in which an impeller, a vane, and a gear are rotated by an electric motor.

  Oil pump 100 and electric oil pump 110 are connected via oil passage 230. The electric oil pump 110 is connected to an oil passage 260 connected to each component of the engine.

  Oil stored in the oil pan 170 is pumped up by the oil pump 100. The oil pumped up by the oil pump 100 is supplied to each component of the engine through the oil passage 230 and the electric oil pump 110. At this time, a filter (1) 140 for adsorbing foreign matter contained in the oil is provided on the oil passage 230 on the electric oil pump 110 side. Here, the foreign matter is not particularly limited, but is, for example, a combustion product such as iron powder or carbon generated by combustion of the engine. An oil passage 240 connected to the oil passage 260 via a relief valve 160 is provided on the oil pump 100 side of the filter (1) 140.

  In addition, an oil passage 250 is provided via a relief valve 130 on the oil pump 230 further on the oil pump 100 side than the oil passage 240. The oil passage 250 is connected to a filter (2) 150 that is coarser than the filter (1) 140. Filter (2) 150 is connected to oil pan 170. The relief valves 130 and 160 are valves that open when the oil pressure in the oil passages 250 and 240 becomes equal to or higher than a predetermined pressure. Note that the pressure at which the relief valve 130 opens is lower than that of the relief valve 160. The relief valve 160 functions as a relief valve of a relief circuit for supplying each component of the engine through the oil passage 240 when the filter (1) 140 cannot filter oil due to clogging or the like. is there.

  Further, a check valve 120 is provided in the passage of the oil passage 230 closer to the oil pump 100 than the position where the oil passage 250 is provided. The check valve 120 is a valve that opens when oil flows from the oil pump 100 toward the electric oil pump 110, and closes when oil flows from the electric oil pump 110 toward the oil pump 100. .

  A flow meter 210 that detects the flow rate of oil flowing through the oil passage 230 is provided on the oil passage 230. The flow meter 210 transmits a detection signal corresponding to the detected oil flow rate to the ECU (Electronic Control Unit) 200. In the present embodiment, the flow meter 210 is provided between the oil pump 100 and the check valve 120 in the oil passage 230, but is not particularly limited.

  The ECU 200 includes a CPU (Central Processing Unit) (not shown) and a memory. The ECU 200 receives an off signal transmitted from the ignition 220 when the ignition 220 is turned off by the driver. ECU 200 also transmits a drive signal to a drive control circuit (not shown) of the electric motor that constitutes electric oil pump 110. The electric oil pump 110 supplies electric power according to the drive signal to the electric motor.

  ECU 200 also controls electric oil pump 110 to switch the oil supply direction. That is, when the electric oil pump 110 receives the switching signal for switching the supply direction transmitted from the ECU 200, the electric oil pump 110 changes the oil supply direction from the oil pump 100 side to the electric oil pump 110 side. Switch to the direction of oil supply to the side. In the present embodiment, the supply direction is switched, for example, by rotating the electric motor in the reverse direction.

  A control structure of a program executed by ECU 200 of the liquid supply apparatus according to the present embodiment will be described with reference to FIG.

  In step (hereinafter, step is abbreviated as S) 1000, ECU 200 determines whether engine stop is detected or not. Here, ECU 200 may detect the stop of the engine based on the off signal transmitted when the ignition 220 is turned off by the driver. Alternatively, in the case of an eco-run vehicle, the predetermined engine stop may be detected. The engine stop may be detected based on whether the condition is satisfied. When engine stop is detected (YES in S1000), the process proceeds to S1050. If not (NO in S1000), the process is repeated until engine stop is detected.

  In S1050, ECU 200 detects the flow rate of oil passage 230 by flow meter 210. In S1100, ECU 200 determines whether or not the detected oil flow rate in oil passage 230 is equal to or greater than a predetermined amount. The predetermined amount is an amount by which it can be determined that the filter performance of the filter (1) 140 is deteriorated. If the detected flow rate is equal to or greater than a predetermined amount (YES in S1100), the process ends. If not (NO in S1100), the process proceeds to S1200.

  In S1200, ECU 200 transmits a switching signal for switching the oil supply direction by electric oil pump 110. At this time, when the electric oil pump 110 receives the switching signal, the electric oil pump 110 switches the supply direction from the electric oil pump 110 side to the oil pump 100 side direction.

  In S1300, ECU 200 determines whether or not a predetermined time has elapsed since the switching signal was transmitted. The predetermined time is a time that does not allow the amount of oil that affects engine start to escape from the oil passage. By switching the supply direction for a predetermined time, it is possible to prevent a delay in the rise of the hydraulic pressure at the start of the engine due to oil loss. If the predetermined time has elapsed (YES in S1300), the process proceeds to S1400. If not (NO in S1300), the process is repeated until a predetermined time elapses.

  In S1400, ECU 200 transmits a switching signal for switching the oil supply direction by electric oil pump 110. At this time, when the electric oil pump 110 receives the switching signal, the electric oil pump 110 switches the supply direction from the oil pump 100 side to the electric oil pump 110 side direction. At this time, the ECU 200 may stop the supply of oil by the electric oil pump 110 when it is not necessary to supply oil to the oil passage according to the stop of the engine.

  An operation of the liquid supply apparatus according to the present embodiment based on the above-described structure and flowchart will be described.

  When ignition 220 is turned off by the driver (YES in S1000), the flow rate of oil flowing through oil passage 230 is detected by flow meter 210 (S1050). If the flow rate through oil passage 230 is not equal to or greater than a predetermined amount (NO in S1100), it is determined that the filter performance of filter (1) 140 is degraded. Therefore, the oil supply direction of electric oil pump 110 is switched from electric oil pump 110 side to oil pump 100 side direction (S1200), and when a predetermined time has elapsed (YES in S1300), electric oil pump 110 side The supply direction is returned from the oil pump 100 side to the electric oil pump 110 side (S1400).

  At this time, when the supply direction is switched, oil is supplied from the electric oil pump 110 side toward the oil pump 100 side. The check valve 120 causes the oil supplied from the electric oil pump 110 to flow to the oil passage 250 side without flowing to the oil pump 100 side. When the oil pressure reaches the pressure that passes through the relief valve 130 in the oil passage 250, the oil flows into the filter (2) 150. Then, the oil that has passed through the filter (2) 150 flows to the oil pan 170. At this time, the foreign matter adhering to the filter (1) 140 moves to the filter (2) 150 as the oil flows. Since the filter (2) 150 is a coarser filter than the filter (1) 140, a relatively large foreign matter adhering to the filter (1) 140 adheres to the filter (2) 150.

  When the supply direction of the electric oil pump 110 is switched from the oil pump 100 side to the electric oil pump 110 side direction after a predetermined time has elapsed, the check valve 120 opens. Therefore, oil flows from the oil pan 170 to the oil pump 100, the filter (1) 140, and the electric oil pump 110. At this time, no oil flows in the oil passage 250 and the filter (2) 150.

  As described above, according to the liquid supply apparatus according to the present embodiment, the flow from the first filter to the second filter is switched by switching the supply direction by the electric oil pump according to the stop of the engine. Can be formed. At this time, the foreign matter adhering to the first filter moves to the second filter. Since the second filter is coarser than the first filter, relatively large foreign matters attached to the first filter can be moved to the second filter. Further, since the mechanical oil pump supplies oil to the first filter without passing through the second filter, foreign matter adhering to the second filter can be held. For this reason, it is possible to prevent the performance of the filter of the first filter, such as the performance and life of the first filter, from being deteriorated. Therefore, it is possible to provide a liquid supply apparatus that can prevent a decrease in the performance of the filter.

  In the present embodiment, when the flow rate detected by the flow meter 210 is not equal to or greater than a predetermined amount, it is determined that the filter performance of the filter (1) 140 has deteriorated and is supplied by the electric oil pump 110. Although the direction is switched, the present invention is not limited to this. For example, the ECU 200 may perform control to switch the supply direction of the electric oil pump 110 every time an engine stop signal is detected, or may output an engine stop signal after a certain period of time based on the number of times the ignition is turned off. When detected, control for switching the supply direction of the electric oil pump 110 may be performed.

<Second Embodiment>
Hereinafter, the liquid supply apparatus according to the second embodiment will be described. Note that components having the same functions as those of the liquid supply device according to the first embodiment described above are denoted by the same reference numerals. Therefore, detailed description thereof will not be repeated here.

  As shown in FIG. 3, a filter (1) 140 is provided on the oil passage 230 on the electric oil pump 110 side. An oil passage 270 is provided on the oil pump 100 side of the filter (1) 140 via a relief valve 190. A filter (2) 150 is connected to the oil passage 270. The filter (2) 150 is connected to one end of the oil passage 280. A check valve 180 that suppresses the flow of oil in the direction from the electric oil pump 110 to the filter (2) 150 is provided on the oil passage 280 whose other end is connected to the electric oil pump 110.

  The electric oil pump 110 is connected to an oil passage 290 connected to each component of the engine. A check valve 300 that suppresses the flow from the oil passage 290 to the electric oil pump 110 is provided on the passage of the oil passage 290.

  The present invention is characterized in that the filter (2) 150 is provided in the relief circuit formed by the oil passages 270 and 280 as described above.

  The control structure of the program executed by ECU 200 of the liquid supply apparatus according to the present embodiment is the same as the control structure of the program executed by ECU 200 of the liquid supply apparatus according to the first embodiment shown in FIG. It is the same flowchart. Therefore, detailed description thereof will not be repeated.

  An operation of the liquid supply apparatus according to the present embodiment based on the above-described structure and flowchart will be described.

  When ignition 220 is turned off by the driver (YES in S1000), the flow rate of oil flowing through oil passage 230 is detected by flow meter 210 (S1050). If the flow rate through oil passage 230 is not equal to or greater than a predetermined amount (NO in S1100), it is determined that the filter performance of filter (1) 140 is degraded. Therefore, when the oil supply direction of electric oil pump 110 is switched (S1200) and a predetermined time has elapsed (YES in S1300), the supply direction of electric oil pump 110 is changed from oil pump 100 side to electric oil pump 110. Return to the side (S1400).

  At this time, when the supply direction is switched, oil is supplied from the electric oil pump 110 side toward the oil pump 100 side. At this time, the oil supplied from the electric oil pump 110 does not flow into the oil pump 100 when the check valve 120 is closed. Therefore, the oil pressure increases in the oil passage 270. When the oil pressure reaches the pressure that passes through the relief valve 190, the oil flows into the filter (2) 150. Then, the oil that has passed through the filter (2) 150 flows through the oil passage 280 and returns to the electric oil pump 110. At this time, in the oil passage 280, no oil flows from the electric oil pump 110 side to the filter (2) 150 side by the check valve 180. Therefore, the foreign matter adhering to the filter (1) 140 moves to the filter (2) 150 along with the oil flow. Since the filter (2) 150 is a coarser filter than the filter (1) 140, a relatively large foreign matter adhering to the filter (1) 140 adheres to the filter (2) 150.

  On the other hand, since the oil on the oil passage 290 does not flow into the electric oil pump 110 by the check valve 300, the oil sent from the oil passage 280 is removed from the filter (1) 140 by the operation of the electric oil pump 110. A circulating flow to the electric oil pump 110 through the filter (2) 150 is formed.

  When the supply direction of the electric oil pump 110 is switched from the oil pump 100 side to the electric oil pump 110 side direction after a predetermined time has elapsed, the check valve 120 opens. Therefore, oil flows from the oil pan 170 to the oil pump 100, the filter (1) 140, and the electric oil pump 110. At this time, no oil flows from the oil passage 270 through the filter (2) 150 to the oil passage 280.

  As described above, according to the liquid supply apparatus according to the present embodiment, in addition to the effects of the liquid supply apparatus according to the first embodiment described above, the oil is relieved by the filter (1) being clogged or the like. In this case, oil can be supplied to each component of the engine after at least the foreign matter is adsorbed by the filter (2).

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows the outline of the whole structure of the liquid supply apparatus which concerns on 1st Embodiment. It is a flowchart which shows the control structure of the program performed with ECU of the liquid supply apparatus which concerns on 1st Embodiment. It is a figure which shows the outline of the whole structure of the liquid supply apparatus which concerns on 2nd Embodiment.

Explanation of symbols

  100 Oil pump, 110 Electric oil pump, 120, 180, 300 Check valve, 130, 160, 190 Relief valve, 140, 150 Filter, 170 Oil pan, 200 ECU, 210 Flow meter, 220 Ignition, 230, 240, 250 260, 270, 280, 290 Oil passage.

Claims (9)

The rotation of the engine, and supply means for supplying liquid to the liquid passage,
An oil pump connected in series to the supply means, receiving supply of electric power, and supplying the liquid to the liquid passage by rotating a rotating member with an electric motor ;
The fluid path between said oil pump and said supply means, a first filter provided in the oil pump side,
A second filter provided in the liquid passage which branches the liquid passage, from the position of the supply means side between said oil pump and said supply means,
Look including a control means for controlling the oil pump to switch the direction of supplying the liquid based on the operating state of the electric motor,
The control means includes a means for controlling the oil pump so as to switch the supply direction until a predetermined time elapses in response to an instruction to stop the engine . The liquid passage is further provided with switching means for switching the passage so that the second filter is positioned downstream of the first filter when the liquid supply direction is switched by the oil pump. The liquid supply apparatus according to claim 1. Said switching means, said a relief valve or check valve is provided between the supply means and the oil pump, the liquid supply apparatus according to claim 2. The liquid supply device further includes a detection means for detecting a flow rate of the liquid flowing in the liquid passage,
The control means includes means for controlling the oil pump to switch the supply direction in response to an instruction to stop the engine when the flow rate detected by the detection means is equal to or less than a predetermined amount. The liquid supply apparatus in any one of Claims 1-3 . The liquid supply device, the the supply direction is switched by the oil pump, further comprising a liquid passage for a flow of the liquid to the upstream side of said supply means from the second filter, according to claim 1 5. The liquid supply device according to any one of 4 above. The liquid supply device, the the supply direction is switched by the oil pump, further comprising a liquid passage for a flow of the liquid into the oil pump from the second filter, any one of claims 1 to 4 liquid supply apparatus according to. The liquid supply apparatus according to claim 1, wherein the second filter is a coarser filter than the first filter. The liquid supply device is a device for supplying the liquid to the engine, the liquid supply apparatus according to claim 1. The liquid supply device is a device for supplying the liquid to the automatic transmission, the liquid supply apparatus according to claim 1.

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