Medium circulating apparatus for improving startability and warm up ability

A medium circulating apparatus of engine oil, which improves startability and warm up ability of an internal combustion engine, includes a microbubble generator that generates microbubbles and mixes the microbubbles into the circulating engine oil. Further, the medium circulating apparatus includes a medium temperature acquiring unit that acquires a temperature of the engine oil. The microbubbles are generated by the microbubble generator when the temperature of the engine oil is less than or equal to a predetermined value in order to decrease a viscosity, a heat conductivity, and a heat capacity of the engine oil in which the microbubbles are mixed.

This is a 371 national phase application of PCT/JP2006/311664 filed 5 Jun. 2006, which claims priority to Japanese Patent Application No. 2005-211791 filed 21 Jul. 2005, the contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a medium circulating apparatus for improving startability and warm up ability, and more particularly to a medium circulating apparatus that circulates a medium through an internal combustion engine or through a transmission.

BACKGROUND OF THE INVENTION

In general, an internal combustion engine and a transmission are installed in a vehicle such as a car, a truck, and a bus, and a medium circulates through the internal combustion engine and the transmission. Internal combustion engine circulating oil (engine oil) used for lubricating a driven part, driving a movable part, and cooling a heated part when the internal combustion engine is driven, represents the medium that circulates through the internal combustion engine. Further, coolant water is a refrigerant or the medium that suppresses rise of a temperature of the internal combustion engine when the internal combustion engine is driven. On the other hand, transmission circulating oil (mission oil) used for lubricating the driven part, driving the movable part, and cooling the heated part when the transmission changes an output of the internal combustion engine depending on a driving state to transmit the output to a road through a wheel, is a medium that circulates through the transmission.

In general, friction at a low temperature state of the internal combustion engine is preferably reduced when the internal combustion engine is started in order to improve startability. Further, the temperature of the internal combustion engine is preferably raised in a short time from the low temperature state while warming up the internal combustion engine in order to improve warm up ability. Here, the medium circulates through the internal combustion engine and through the transmission at the low temperature state even at the starting and the warming up of the internal combustion engine. Therefore, startability and warm up ability of the internal combustion engine cannot be improved since the medium at the low temperature state circulates therethrough.

In the engine oil and in the mission oil for example, the friction cannot be reduced compared to the friction thereof at a high temperature even if the driven part of the internal combustion engine or the transmission that is connected to the internal combustion engine is lubricated since viscosities of the engine oil and the mission oil increase as the temperatures thereof decrease. Further, a rate at which the temperature of the internal combustion engine rises slows down as the temperature of the coolant water decreases since the coolant water receives heat generated by the internal combustion engine through which the coolant water circulates.

A technique in which an apparent viscosity of the oil is decreased is proposed. For example, Japanese Utility Model Application Laid-Open (JP-U) No. S63-78122 discloses a cooling device that cools the internal combustion engine by circulating the oil through an oil jacket formed on a cylinder block of the internal combustion engine. In the cooling device, a bubble generator is disposed at a predetermined position of the oil jacket to mix fine bubbles into the oil so that the apparent viscosity of the oil is decreased.

In JP-U No. S63-78122, air is injected from one side of an ultrafine fine mesh net and one side of ultrafine small holes drilled and formed on a surface of the bubble generator, to other side thereof to generate ultrafine bubbles. A diameter of the ultrafine bubble is required to be less than or equal to 1 mm. However, the bubbles generated by the small holes and the net can be visually recognized even if the bubbles are said to be small, because for example, the bubble has the diameter of approximately 0.2 mm. Therefore, the bubbles might become larger bubbles by absorbing and combining with each other. Consequently, a pump that sucks and discharges the oil sucks the large bubbles when the oil is circulated, and discharge ability of the pump might decrease. Thus, friction might increase since enough engine oil is not supplied to a section to be lubricated of the driven part of the internal combustion engine.

SUMMARY OF INVENTION

The present invention is provided in view of the foregoing, and an object of the present invention is to provide a medium circulating apparatus that can improve at least one of startability and warm up ability of an internal combustion engine.

In order to solve the problem and to achieve the object, a medium circulating apparatus for improving startability and warm up ability according to one aspect of the present invention is for circulating a medium through an internal combustion engine or through a transmission, and includes a microbubble generator that generates microbubbles and mixes the microbubbles into the medium, and a medium temperature acquiring unit that acquires a temperature of the medium. The microbubble generator generates the microbubbles when the acquired temperature of the medium is less than or equal to a predetermined value.

In the medium circulating apparatus, the medium may preferably be at least one of internal combustion engine circulating oil that circulates through a circulating oil circulating route passing through the internal combustion engine, coolant water that circulates through a coolant water circulating route passing through the internal combustion engine, a transmission circulating oil that circulates through circulating oil circulating route passing through the transmission.

According to this medium circulating apparatus, the microbubble generator mixes ultrafine bubbles difficult to visually recognize, that are the microbubbles, into the medium such as the internal combustion engine circulating oil, the coolant water, and the transmission circulating oil, that circulates through the internal combustion engine. When the microbubbles are mixed into the medium, disturbance at a boundary layer between the medium and the section to be lubricated of the driven part is suppressed by the microbubbles mixed into the medium. Further, a contact area between a liquid section of the medium excluding the microbubbles and a section that contacts with the medium inside the internal combustion engine or inside the transmission such as the section to be lubricated of the driven part is reduced. Furthermore, the gas in the microbubbles has low heat capacity compared to heat capacity of the medium. Therefore, the medium in which the microbubbles are mixed can decrease the viscosity, the heat conductivity, and the heat capacity, compared to a medium in which the microbubbles are not mixed. Consequently, the friction caused when the driven part of the internal combustion engine is lubricated by the medium can be reduced even if the temperature of the medium is low since the viscosity of the medium can be decreased. Further, the medium can hardly receive the heat generated by the internal combustion engine or the transmission through which the medium is circulated even if the temperature of the medium is low since the heat conductivity and the heat capacity can be decreased. Consequently, the temperature of the internal combustion engine can be raised easily.

Further, the enlarging of the microbubbles can be suppressed since the microbubbles mixed into the medium are hardly absorbed and combined with each other even if the microbubbles float within the medium for a long time. Consequently, the decrease in the discharging ability of the pump is suppressed even if the pump that sucks, pressurizes, and discharges the medium to circulate the medium through the internal combustion engine or through the transmission is used. Here, the microbubbles are mixed into the medium.

The medium circulating apparatus according to the present invention may include a circulating oil storage that includes a plurality of tanks storing the internal combustion engine circulating oil, and performs communicative connection between the tanks depending on a temperature of the engine oil. The circulating oil storage does not perform the communicative connection between the tanks when the acquired temperature of the engine oil is less than or equal to a predetermined value.

According to this medium circulating apparatus, each of the tanks are not communicatively connected to each other when the acquired temperature of the engine oil is less than or equal to the predetermined value. Thus, the engine oil stored in certain tanks circulates through the internal combustion engine. That is to say, an amount of the engine oil circulating through the internal combustion engine can be decreased when the temperature of the engine oil is low. Therefore, the mixed quantity of the microbubbles mixed into the engine oil can be increased in a short time since the amount of the engine oil in which the microbubbles generated by the microbubble generator is mixed can be decreased. Consequently, startability and warm up ability of the internal combustion engine can be improved since the viscosity, the heat conductivity, and the heat capacity of the engine oil can be decreased in a short time.

In the medium circulating apparatus according to the present invention, the coolant water circulating route may include a starting circulating route that is provided with the microbubble generator at a middle thereof, and guides the coolant water into the internal combustion engine, and a driving circulating route that includes a coolant unit cooling the coolant water and is communicatively connected to the starting circulating route depending on a temperature of the coolant water. The coolant water circulating route does not perform the communicative connection between the starting circulating route and the driving circulating route when the acquired temperature of the medium is less than or equal to a predetermined value.

According to this medium circulating apparatus, the starting circulating route and the driving circulating route are not communicatively connected to each other when the acquired temperature of the coolant water is less than or equal to the predetermined value. Hence, only the coolant water flowing through the starting circulating route circulates through the internal combustion engine. That is to say, an amount of the coolant water circulating through the internal combustion engine can be decreased when the temperature of the coolant water is low. Therefore, the mixed quantity of the microbubbles mixed into the coolant water can be increased in a short time since the amount of the coolant water in which the microbubbles generated by the microbubble generator are mixed can be decreased. Consequently, warm up ability of the internal combustion engine can be improved since the heat conductivity and the heat capacity of the coolant water can be decreased in a short time.

The medium circulating apparatus according to the present invention may include an ultrasonic wave generator that generates an ultrasonic wave depending on the gas in the microbubbles generated by the microbubble generator, irradiates the medium in which the microbubbles are mixed with the ultrasonic wave. The ultrasonic wave is generated by the ultrasonic wave generator when the acquired temperature of the medium is less than or equal to a predetermined value.

According to the present invention, the microbubbles mixed into the medium by the microbubble generator can distribute uniformly with respect to the medium. The ultrasonic wave generator irradiates the medium in which the microbubbles are uniformly distributed with the ultrasonic wave depending on the gas in the microbubbles. That is to say, the ultrasonic wave has a frequency that can contract and break the microbubbles mixed into the medium. Therefore, the microbubbles that are uniformly distributed with respect to the medium are contracted and broken by the irradiation with the ultrasonic wave, and the temperature of the gas in the microbubbles is raised instantaneously. Consequently, the viscosity of the medium can be further decreased since the temperature of the medium circulating through the internal combustion engine or through the transmission is raised uniformly and instantaneously so that the friction caused when the driven part of the internal combustion engine is lubricated can be further reduced. Further, the medium can hardly receive the heat generated by the internal combustion engine or the transmission through which the medium is circulated since the temperature of the medium circulating through the internal combustion engine or through the transmission can be raised uniformly and instantaneously, so that the temperature of the internal combustion engine can be raised even more easily.

The medium circulating apparatus according to the present invention can reduce viscosity, heat conductivity, and heat capacity of a medium by mixing microbubbles into the medium that circulates through an internal combustion engine or through a transmission; therefore, startability and warm up ability of the internal combustion engine can be improved.

DETAILED DESCRIPTION

Embodiments of a medium circulating apparatus for improving startability and warm up ability according to the present invention are explained below with reference to accompanying drawings; however, the present invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, elements in the following embodiments include elements that can be easily assumed by those skilled in the art or the equivalents thereof. The medium circulating apparatus explained below is a device that circulates a medium through an internal combustion engine such as a gasoline engine, a diesel engine, and an LPG engine (Liquefied Petroleum Gas), or through a transmission that transmits an output of the internal combustion engine to a wheel. Here, the internal combustion engine and the transmission are installed in a vehicle such as a car and a truck.

FIG. 1is a schematic drawing of the medium circulating apparatus according to a first embodiment.FIG. 2Ais a schematic drawing of a microbubble generator.FIG. 2Bis an enlarged view of a relevant part of the microbubble generator.FIG. 3Ais a schematic drawing of an ultrasonic wave generator.FIG. 3Bis a schematic drawing of a state of microbubbles. A medium circulating apparatus1-1according to the first embodiment uses internal combustion engine circulating oil (hereinafter simply referred to as engine oil) as the medium for the internal combustion engine that lubricate a driven part, drives a movable part, and cools a heated part, when an internal combustion engine100is driven. The medium circulating apparatus1-1according to the first embodiment circulates the engine oil through an engine oil circulating route6that is a circulating oil circulating route passing through the internal combustion engine100. The medium circulating apparatus1-1is configured by an oil pan2, an engine oil pump3, a microbubble generator4, an ultrasonic wave generator5, an engine oil circulating route6, and a medium circulation controller7. The engine oil circulating route6includes a space, a path formed inside the internal combustion engine100, and the like. Here, the engine oil flows through the path. That is to say, the engine oil circulating route6includes the path and the space such as a path that supplies the engine oil to a section to be lubricated of the driven part, to a section to be driven of the movable part, and to a section to be cooled of the heated part of the internal combustion engine100, another path that is used to carry the supplied engine oil back to the oil pan2, and a space (for example, a crankcase represents the space).

The oil pan2is arranged in a middle of the engine oil circulating route6as shown inFIG. 1, and the oil pan2is a circulating oil storage that stores the engine oil circulating through the internal combustion engine100. The oil pan2is configured by a plurality of tanks and a unit that controls communicative connection within the tanks. In the first embodiment, the oil pan2is configured by two tanks21,22, and a switchover valve23that controls the communicative connection between the tanks21and22. Each of the tanks21and22is attached at a bottom of the internal combustion engine100, and the engine oil circulated through the internal combustion engine100returns to the tanks to be stored therein. The oil pan2is connected to at least one tank of the plurality of the tanks, and the tank21is connected to the engine oil circulating route6in the first embodiment. Therefore, the engine oil stored inside the tank21again circulates through the internal combustion engine100by the engine oil circulating route6.

Further, the changeover valve23opens and closes based on a changeover valve opening and closing signal outputted from the medium circulation controller7. Therefore, the engine oil stored in the tank22circulates through the internal combustion engine100by the engine oil circulating route6since the engine oil stored in the tank22is flowed into the tank21by opening the change over valve23to communicatively connect the tanks21and22. On the other hand, each of the tanks21and22are not communicatively connected when the changeover valve23is closed. Hence, the engine oil stored in the tank22does not flow into the tank21so that only the engine oil stored in the tank21circulates through the internal combustion engine100by the engine oil circulating route6. That is to say, an amount of the engine oil that circulates through the internal combustion engine100can be controlled by controlling the changeover valve23to communicatively connect the tanks21and22.

The engine oil pump3is arranged at a middle of the engine oil circulating route6as shown inFIG. 1, and the engine oil pump3pressurizes the engine oil stored in the oil pan2and supplies to the engine oil circulating route6. The engine oil pump3is connected to the tank21of the oil pan2through an oil circulating path61, and the engine oil pump3is connected to the microbubble generator4through an oil circulating path62. Therefore, the engine oil stored in the oil pan2is sucked by the engine oil pump3through the oil circulating path61, and the engine oil is pressurized by the engine oil pump3. The pressurized engine oil is discharged into the oil circulating path62, and the pressurized engine oil is flowed into the microbubble generator4as shown by an arrow A ofFIGS. 1 and 2. The engine oil pump3is activated by an output generated by driving the internal combustion engine100. For example, the engine oil pump3is activated by torque generated at a crank shaft not shown of the internal combustion engine100.

Microbubbles M are generated from air, which is gas, by the microbubble generator4as shown inFIGS. 1 to 2A. The microbubble generator4is arranged at a middle of the engine oil circulating route6, and the microbubble generator4mixes the generated microbubbles M into the medium flowing through the microbubble generator4. Here, the medium is the engine oil, in the first embodiment. The microbubble generator4is configured by a bubble generator main body41, a gas introduction control valve42, and a gas introduction path43. The microbubble generator4is connected to the ultrasonic wave generator5through an oil circulating path63. Therefore, the engine oil in which the generated microbubbles M are mixed is flowed into the ultrasonic wave generator5as shown by an arrow B inFIGS. 1,2A, and3A. Here, the microbubbles M are ultrafine bubbles difficult to visually recognize, and a diameter thereof is 50 μm and preferably has the diameter lying in a range between 20 μm and 30 μm. The microbubbles M are difficult to be absorbed by each other and difficult to be combined with each other, and the microbubbles M can float within the medium for a long time.

The bubble generator main body41generates the microbubbles M, and the bubble generator main body41mixes the generated microbubbles M into the engine oil flowing out from the oil circulating path62. Then, the engine oil flows into the oil circulating path63. A bubble generator41ais formed in the bubble generator main body41. The microbubble generator4generates the microbubbles M from gas supplied to the bubble generator41aby shear force caused by the injection of the engine oil into the bubble generator41a.

A medium introduction path41band a gas introduction path41cthat are both communicatively connected to the bubble generator41aare formed in the bubble generator main body41. One end of the bubble generator41aat a downstream side with respect to a flow direction of the engine oil is opened and is communicatively connected to the oil circulating path63. Further, a gas opening41dthat communicatively connects to one end of the gas introduction path41cis formed at the center of the cross-sectioned bubble generator41aand at an end of an upstream side with respect to the flow direction of the engine oil. A plurality of medium openings41ethat communicatively connect to one end of the medium introduction path41b(this refer to branched plurality of ends in the present embodiment) are formed around the gas opening41dat the end of the upstream side. Other end of the medium introduction path41b(an end at the upstream side with respect to the flow direction of the engine oil) is connected to the oil circulating path62. Further, other end of the gas introduction path41cis connected to one end of the gas introduction path43.

The gas introduction control valve42is provided at a middle of the gas introduction path43. The gas introduction control valve42opens and closes based on a control valve opening and closing signal outputted from the medium circulation controller7.

In the first embodiment, one end of the gas introduction path43is connected to a gas tank (not shown) that stores high pressure gas therein. A pressure of the engine oil decreases as injecting the engine oil into the bubble generator41aof the bubble generator main body41; therefore, the gas is supplied to the bubble generator41athrough the gas introduction path43due to the pressure difference between the gas and the engine oil.

The ultrasonic wave generator5generates an ultrasonic wave E as shown inFIGS. 1 and 3A, and the ultrasonic wave generator5is arranged at a middle of the engine oil circulating route6. The ultrasonic wave generator5irradiates the medium in which the microbubbles M are mixed with the ultrasonic wave E, and the ultrasonic wave generator5irradiates the engine oil in which the microbubbles M are mixed with the ultrasonic wave E in the first embodiment. The ultrasonic wave generator5is configured by an ultrasonic wave irradiate path51, an oscillator52, and an oscillator circuit53. The ultrasonic wave generator5is connected to a path not shown formed inside the internal combustion engine100used for supplying the engine oil, through an oil circulating path64. Therefore, the engine oil in which the microbubbles M irradiated with the ultrasonic wave E are mixed is supplied into the internal combustion engine100as shown by an arrow C ofFIGS. 1 and 3A, and the engine oil is supplied to the section to be lubricated of the driven part, to the section to be driven of the movable part, and to the section to be cooled of the heated part, inside the internal combustion engine100. Consequently, the driven part of the internal combustion engine100is lubricated, the movable part of the internal combustion engine100is driven, and the heated part of the internal combustion engine is cooled. The engine oil used to lubricate the driven part, to drive the movable part, and to cool the heated part, is returned to the oil pan2.

Here, the ultrasonic wave E has a frequency capable of contracting and breaking the gas in the microbubbles M, which are generated by the microbubble generator4and mixed into the medium. The ultrasonic wave E according to the first embodiment has a frequency capable of contracting and breaking the air that configures the microbubbles M mixed into the engine oil.

One end (an end at the upstream side with respect to the flow direction of the engine oil) of the ultrasonic wave irradiate path51is connected to the oil circulating path63, and other end thereof (an end at the downstream side with respect to the flow direction of the engine oil) is connected to the oil circulating path64. The oscillator52is provided so that a focal point of the oscillator52(a focal point of the ultrasonic wave generated by the oscillator52) is set within the ultrasonic wave irradiate path51. The oscillator52is connected to the oscillator circuit53, and the oscillator52is activated by an oscillator activate signal outputted to the oscillator circuit53from the medium circulation controller7.

Here,64arepresents an engine oil temperature sensor, which is a medium temperature detector that detects the temperature of the engine oil supplied into the internal combustion engine100, for outputting the temperature to the medium circulation controller7.

The medium circulation controller7mainly is a bubble generation controller that controls the generation of the microbubbles M as well as is an ultrasonic wave generation controller that controls the generation of the ultrasonic wave. A medium temperature detected by the medium temperature detector is inputted to the medium circulation controller7to control the microbubble generator4and the ultrasonic wave generator5based on the medium temperature. In the first embodiment, the medium temperature described above refers to the engine oil temperature detected by the engine oil temperature sensor64a.

Specifically, the medium circulation controller7is configured by an input and output part (I/O)71that inputs and outputs the input signal and the output signal, a processor72that at least has functions of controlling the generation of the microbubbles M by the microbubble generator4and the generation of the ultrasonic wave E by the ultrasonic wave generator5, and a memory73. The processor72includes a medium temperature acquiring unit74, a changeover valve controller75, a bubble generation controller76, and an ultrasonic wave generation controller77. Further, the processor72can be configured by the memory and a CPU (Central Processing Unit), and control of the medium circulating apparatus1-1can be realized by loading a program to the memory and executing the program. The program is based on a way of controlling the microbubble generator4, a way of controlling the ultrasonic wave generator5, and the like. The memory73can be configured by a nonvolatile memory such as a flash memory, a memory that is readable such as a ROM (Read Only Memory), a memory that is readable and writable such as a RAM (Random Access Memory), or a combination of the memories mentioned. The medium circulation controller7is not necessarily configured separately. An ECU (Engine Control Unit) that controls the driving of the internal combustion engine100may include the function of the medium circulation controller7.

An operation of the medium circulating apparatus1-1according to the first embodiment is explained next. More particularly, a way of controlling the microbubble generator4and the ultrasonic wave generator5is explained.FIG. 4is a control flow chart of the medium circulating apparatus1-1according to the first embodiment. Here, the engine oil circulates constantly through the engine oil circulating route6from the start until the stop of the internal combustion engine100since the engine oil pump3is activated when the internal combustion engine100is driven.

The medium temperature acquiring unit74of the processor72of the medium circulation controller7acquires a temperature T1of the engine oil, that is the medium, while the engine oil circulates through the internal combustion engine100due to the driving of the internal combustion engine100(step ST101). Specifically, the medium temperature acquiring unit74acquires the temperature T1of the engine oil circulating through the internal combustion engine100. Here, the engine oil temperature T1is detected by the engine oil temperature sensor64a, and the temperature T1is outputted to the medium circulation controller7.

Next, the changeover valve controller75of the processor72determines whether the temperature T1of the engine oil acquired by the medium temperature acquiring unit74is less than or equal to a predetermined value T2or not (step ST102). Here, the predetermined value T2is a temperature at which viscosity of the engine oil circulating through the internal combustion engine100becomes high and starting of the internal combustion engine100becomes difficult. For example, the predetermined temperature T2represents a temperature of the engine oil at a cold start of the internal combustion engine100. The medium temperature acquiring unit74of the processor72repeats acquiring the temperature T1of the engine oil until the acquired temperature T1of the engine oil becomes less than or equal to the predetermined value T2.

Next, the changeover valve controller75of the processor72closes the changeover valve23when the changeover valve controller75determines that the temperature T1of the engine oil supplied to the internal combustion engine100is less than or equal to the predetermined value T2(step ST103). Specifically, the changeover valve controller75outputs a changeover valve opening and closing signal to the changeover valve23to close the changeover valve23. That is to say, the engine oil circulating through the engine oil circulating route6becomes only the engine oil that is stored in the tank21of the oil pan2.

Next, the bubble generation controller76of the processor72activates the microbubble generator4when the temperature T1of the engine oil supplied to the internal combustion engine100is less than or equal to the predetermined value T2, while closing the changeover valve23(step ST104). Specifically, the bubble generation controller76outputs a control valve opening and closing signal to the gas introduction control valve42to open the gas introduction control valve42. Consequently, the air is supplied from the gas opening41dto the bubble generator41athrough the gas introduction path43and through the gas introduction path41cdue to the pressure difference between the air and the engine oil, as described above.

The engine oil pressurized by the engine oil pump3is supplied from the medium opening41eto the bubble generator41athrough the oil circulating path62and through the medium introduction path41b. Therefore, the microbubbles M are generated from the air supplied to the bubble generator41aby shear force caused by the injection of the pressurized engine oil into the bubble generator41a, and the microbubbles M are mixed into the engine oil flowing into the oil circulating path63from the bubble generator41a(seeFIGS. 2A and 2B). Hence, the microbubble generator4generates the microbubbles M, and mixes the generated microbubbles M into the engine oil, that is the medium. The microbubble generator4can uniformly mix the generated microbubbles M into the engine oil since the microbubble generator4generates the microbubbles M with respect to the engine oil flowing through the bubble generator41a. That is to say, the microbubbles M can be uniformly distributed within the engine oil.

FIG. 5is a graph showing a relationship between a property of the medium and a mixed quantity of the microbubbles. As shown inFIG. 5, when the microbubbles M are mixed into the medium, which is the engine oil in the first embodiment, the viscosity, a heat conductivity, and a heat capacity of the medium are decreased according to the amount of the microbubbles M mixed into the medium. It is considered that the reason for the decrease in the viscosity of the medium is that disturbance at a boundary layer between the section to be lubricated of the driven part and the medium is suppressed by the microbubbles mixed into the medium. Further, it is considered that the viscosity of the medium is decreased since the contact area of the liquid section excluding the microbubbles in the medium and the section to be lubricated of the contacted part is reduced due to density decrease of the medium caused by the microbubbles mixed into the medium. Further, it is considered that the reason for the decrease in the heat conductivity of the medium is that the density of the medium is decreased by the microbubbles mixed into the medium. Consequently, the contact area between the liquid section excluding the microbubbles in the medium and the section that contacts with the medium inside the internal combustion engine100or inside the transmission200is decreased. Furthermore, the reason for the decrease in the heat capacity of the medium is that the heat capacity of the gas in the microbubbles M mixed into the medium is lower than the heat capacity of the medium. Therefore, the medium in which the microbubbles M are mixed can decrease the viscosity, the heat conductivity, and the heat capacity, compared to the viscosity, the heat conductivity, and the heat capacity of the medium in which the microbubbles M are not mixed.

As described above, the amount of the engine oil circulating through the internal combustion engine100can be decreased when the changeover valve23is closed, compared to the amount of the engine oil when the changeover valve23is opened. Therefore, more engine oil circulating through the internal combustion engine100flows through the microbubble generator4when the temperature T1of the engine oil is low so that the amount of the microbubbles mixed into the engine oil is increased in a short time. Consequently, the viscosity, the heat conductivity, and the heat capacity of the engine oil can be decreased in the short time.

Next, the ultrasonic wave generation controller77of the processor72activates the ultrasonic wave generator5while the microbubble generator4is activated (step ST105). Specifically, the ultrasonic wave generation controller77outputs the oscillator activate signal to the oscillator circuit53, and the oscillator circuit53activates the oscillator52. Consequently, the oscillator52generates the ultrasonic wave E as described above. In the present embodiment, the ultrasonic wave E has the frequency capable of contracting the air which is the gas in the microbubbles M, and breaking the microbubbles M. The ultrasonic wave generator5irradiates the pressurized engine oil, in which the microbubbles M are mixed, flowing through the ultrasonic wave irradiate path51with the ultrasonic wave E (seeFIG. 3A). Hence, the ultrasonic wave generation controller77generates the ultrasonic wave E, and the ultrasonic wave generation controller77irradiates the engine oil, in which the microbubbles M are mixed, with the ultrasonic wave E.

The microbubbles M mixed into the engine oil and to be irradiated with the ultrasonic wave E contract to become small microbubbles M′ and break inside the engine oil as shown inFIG. 3B. The microbubbles M mixed into the engine oil repeat the contraction in a short time when the engine oil is irradiated with the ultrasonic wave E so that the temperatures of the microbubbles M′ are raised instantaneously. Further, a part of the microbubbles M that are mixed into the engine oil break due to the irradiation with the ultrasonic wave E; therefore, the energy from the breaking of the microbubbles is converted into heat energy so that the temperature of the engine oil is raised instantaneously. Consequently, the temperature T1of the engine oil in which the microbubbles M are mixed is raised instantaneously. The temperature T1of the engine oil can uniformly be raised since the microbubbles M are uniformly distributed in the engine oil, as described above.

The engine oil in which the temperature T1is raised instantaneously is supplied into the internal combustion engine100with the microbubbles M that are mixed into the engine oil. The engine oil supplied into the internal combustion engine100is supplied to the section to be lubricated of the driven part, the section to be driven of the movable part, and the section to be cooled of the heated part of the internal combustion engine100, through the path not shown. The viscosity, the heat conductivity, and the heat capacity of the engine oil supplied thereto are decreased.

Therefore, the friction caused when the driven part of the internal combustion engine100is lubricated can be reduced by the engine oil even if the temperature of the internal combustion engine100is low and the temperature of the engine oil is low, whereby startability of the internal combustion engine100can be improved. Further, the medium can hardly receive the heat generated by the internal combustion engine100through which the engine oil is circulated even if the temperature of the internal combustion engine100is low and the temperature of the engine oil is low so that the temperature of the internal combustion engine100can be easily raised. Therefore, warm up ability of the internal combustion engine100can be improved. Startability and warm up ability of the internal combustion engine100can be improved as explained above; therefore, fuel consumption can be improved and degradation of emission can be suppressed.

Further, startability of the internal combustion engine can be further improved since the temperature T1of the engine oil supplied into the internal combustion engine100is increased and the viscosity is further decreased. Furthermore, warm up ability of the internal combustion engine100can be further improved since the temperature T1of the engine oil supplied into the internal combustion engine100is increased so that the engine oil circulating through the internal combustion engine100can hardly receive the heat generated by the internal combustion engine100.

Each of the tanks21and22are communicatively connected to each other by the medium circulation controller7that controls the opening and closing of the changeover valve23in the above first embodiment; however, the present invention is not limited to the above first embodiment. For example, each of the tanks21and22can be communicatively connected to each other by a thermostat or a valve formed by a shape memory alloy. The thermostat and the valve are set so that the each of the tanks21and22are communicatively connected to each other when the temperature T1of the engine oil circulating through the internal combustion engine100exceeds the predetermined value T2.

The microbubble generator4is provided at the middle of the engine oil circulating route6in the first embodiment; however, the present invention is not limited to the above first embodiment. For example, the microbubble generator4can mix the generated microbubbles M into the engine oil stored in the oil pan2. Specifically, the microbubble generator4mixes the generated microbubbles M into the engine oil stored in the tank21that is connected to the engine oil circulating route6.

A medium circulating apparatus1-2according to a second embodiment is explained below.FIG. 6is a schematic drawing of the medium circulating apparatus according to the second embodiment. The medium circulating apparatus1-2according to the second embodiment uses coolant water, which mainly cools the heated part, as the medium when the internal combustion engine100is driven. The medium circulating apparatus1-2according to the second embodiment circulates the coolant water by a coolant water circulating route8that passes through the internal combustion engine100. Most of parts of the medium circulating apparatus1-2according to the second embodiment are similar to the medium circulating apparatus1-1according to the first embodiment; therefore, explanations for the identical parts (numbers inFIG. 6that are identical to the numbers inFIG. 1) are not repeated.

The medium circulating apparatus1-2is configured by a water pump9, the microbubble generator4, the ultrasonic wave generator5, the coolant water circulating route8, and the medium circulation controller7. The coolant water circulating route8includes a space, a path, and the like, that are formed inside the internal combustion engine100, through which the coolant water flows. Hence, the coolant water circulating route8includes a path, a space (for example, water jacket), and the like used for supplying the coolant water to the cooling section of the heated part of the internal combustion engine100.

The coolant water circulating route8is configured by a starting circulating route81and a driving circulating route82, as shown inFIG. 6. The starting circulating route81is configured by a plurality of coolant water circulating paths83to86. The microbubble generator4, the ultrasonic wave generator5, and the water pump9are arranged at a middle of the starting circulating route81, and the starting circulating route81is a route so that the coolant water flows through the internal combustion engine100. On the other hand, the driving circulating route82is configured by a coolant water circulating path87that is branched from the coolant water circulating path83connected to the water pump9and joins to the coolant water circulating path83. A radiator88, which is a cooling unit to cool the coolant water, is arranged at a middle of the driving circulating route82, and the coolant water flows through the radiator88.

A thermostat89communicatively connects the coolant water circulating path83and the coolant water circulating path87based on a temperature T3of the coolant water that flows through the thermostat89. Therefore, the coolant water inside the coolant water circulating path87and inside the radiator88flows into the coolant water circulating path83when the thermostat89is opened so that the coolant water of the driving circulating route82circulates through the internal combustion engine100by the starting circulating route81. On the other hand, the coolant water inside the coolant water circulating path87and inside the radiator88does not flow into the coolant water circulating path83when the thermostat89is closed so that only the coolant water of the starting circulating route81circulates through the internal combustion engine100. That is to say, the amount of the coolant water circulating through the internal combustion engine100can be controlled by controlling the communicative connection of the starting circulating route81and the driving circulating route82by the thermostat89. Here,86ais a coolant water temperature sensor that is the medium temperature detector to detect the temperature of the coolant water supplied into the internal combustion engine100and to output the detected temperature to the medium circulation controller7. Further,88ais a fan that performs forced cooling of the coolant water flowing through the radiator88.

The water pump9is arranged at a middle of the starting circulating route81of the coolant water circulating route8. The water pump9pressurizes the coolant water carried back to the coolant water circulating path83after flowing through the internal combustion engine, to supply the coolant water again into the internal combustion engine100through the microbubble generator4and the ultrasonic wave generator5. The water pump9is activated due to an output generated by driving the internal combustion engine100. For example, the water pump9is activated by the torque generated by the crank shaft not shown of the internal combustion engine100.

Next, an operation of the medium circulating apparatus1-2according to the second embodiment is explained.FIG. 7is a control flow chart of the medium circulating apparatus according to the second embodiment. Explanations of the operation of the medium circulating apparatus1-2according to the second embodiment that is identical to the operation of the medium circulating apparatus1-1according to the first embodiment are not repeated. In the second embodiment, the coolant water constantly circulates through the coolant water circulating route8from the start until the stop of the internal combustion engine100since the water pump9is activated with the driving of the internal combustion engine100.

First, the medium temperature acquiring unit74of the processor72of the medium circulation controller7acquires the temperature T3of the coolant water, that is the medium, when the coolant water circulates through the internal combustion engine100due to the driving of the internal combustion engine100(step ST201). Specifically, the medium temperature acquiring unit74acquires the temperature T3of the coolant water that circulates through the internal combustion engine100. Here the temperature T3is detected by the coolant water temperature sensor86a, and the temperature T3is outputted to the medium circulation controller7.

Next, the bubble generation controller76of the processor72determines whether the acquired temperature T3of the coolant water is less than or equal to a predetermined value T4(step ST202). Here, the predetermined value T4is a temperature at which the temperature of the coolant water circulating through the internal combustion engine100is low so that it is easier for the coolant water to receive the heat generated by the internal combustion engine100. For example, it is a temperature of the coolant water at the cold start of the internal combustion engine100. The medium temperature acquiring unit74of the processor72repeats to acquire the temperature T3of the coolant water until the acquired temperature T3of the coolant water becomes less than or equal to the predetermined value T4.

Next, the bubble generation controller76of the processor72activates the microbubble generator4when the bubble generation controller76determines that the temperature T3of the coolant water supplied to the internal combustion engine100is less than or equal to the predetermined value T4(step ST203). At this time, the thermostat89is closed or maintaining the closing state since the temperature T3of the coolant water supplied to the internal combustion engine100is less than or equal to the predetermined value T4. Therefore, the coolant water circulating through the internal combustion engine100is only the coolant water inside the starting circulating route81.

The microbubbles M are generated by activating the microbubble generator4, and the generated microbubbles M are mixed into the coolant water, which is the medium. Therefore, the coolant water in which the microbubbles M are mixed can decrease the viscosity, the heat conductivity, and the heat capacity compared to the coolant water in which the microbubbles M are not mixed.

The amount of the coolant water circulating through the internal combustion engine100when the thermostat89is closed is less than the amount of the coolant water when the thermostat89is opened due to the amount of the coolant water inside the driving circulating route82and inside the radiator88. Therefore, more coolant water circulating through the internal combustion engine100flows through the microbubble generator4when the temperature T3of the coolant water is low, whereby the amount of the microbubbles M mixed into the coolant water is increased in a short time. Consequently, the viscosity, the heat conductivity, and the heat capacity, of the coolant water can be decreased in the short time.

Next, the ultrasonic wave generation controller77of the processor72activates the ultrasonic wave generator5while the microbubble generator4is activated (step ST204). The ultrasonic wave generator5generates the ultrasonic wave E, and the ultrasonic wave generator5irradiates the coolant water in which the microbubbles M are mixed with the ultrasonic wave E (seeFIG. 3A). The temperature T3of the coolant water in which the microbubbles M are mixed is uniformly and instantaneously raised since the microbubbles M, that are to be irradiated with the ultrasonic wave E and distributed uniformly within the coolant water, become the small microbubbles M′ by the contraction or the break thereof.

The coolant water in which the temperature T3is instantaneously raised is supplied into the internal combustion engine100with the microbubbles M that are mixed into the coolant water. The coolant water supplied into the internal combustion engine100is supplied to the section to be cooled of the heated part of the internal combustion engine100through a path not shown. The heat conductivity and the heat capacity of the supplied coolant water are decreased.

Therefore, warm up ability of the internal combustion engine100can be improved since it becomes difficult to receive the heat generated by the internal combustion engine100through which the coolant water circulates even if the temperature of the internal combustion engine100and the temperature of the coolant water are low so that it becomes easier to increase the temperature of the internal combustion engine100. Therefore, fuel consumption can be improved and degradation of emission can be suppressed since warm up ability of the internal combustion engine100can be improved as described above.

Further, warm up ability of the internal combustion engine100can be further improved since the temperature T3of the coolant water supplied into the internal combustion engine100is raised so that it is difficult to further receive the heat generated by the internal combustion engine100through which the coolant water flows.

Next, a medium circulating apparatus1-3according to a third embodiment is explained.FIG. 8is a schematic drawing of the medium circulating apparatus according to the third embodiment. The medium circulating apparatus1-3according to the third embodiment is connected to the internal combustion engine100. Further, the medium circulating apparatus1-3uses transmission circulating oil (hereinbelow simply referred to as mission oil) as the medium, and the medium circulating apparatus1-3lubricates the driven part, drives the movable part, and cools the heated part when the transmission is activated by driving the internal combustion engine100. The medium circulating apparatus1-3circulates the mission oil by a mission oil circulating route11, which is the circulating oil circulation route passing through the transmission200. Here, most of fundamental configurations of the medium circulating apparatus1-3according to the third embodiment are similar to the fundamental configurations of the medium circulating apparatus1-1according to the first embodiment; therefore, explanations for the identical parts (numbers inFIG. 8that are the same as the numbers inFIG. 1) are not repeated.

The medium circulating apparatus1-3is configured by a mission oil pump10, the microbubble generator4, the ultrasonic wave generator5, the mission oil circulating route11, and the medium circulation controller7. The mission oil circulating route11includes a space and a path formed inside the internal combustion engine100other than mission oil circulating paths111to113that connect the mission oil pump10, the microbubble generator4, the ultrasonic wave generator5, and the like. Here, the mission oil flows through the paths. That is to say, the mission oil circulating route11includes the path used for supplying the mission oil to the section to be lubricated of the driven part, the section to be driven of the movable part, and the section to be cooled of the heated part, of the transmission200. Here,113arepresents a mission oil temperature sensor that is the medium temperature detector for detecting the temperature of the mission oil supplied into the internal combustion engine100, and for outputting the temperature to the medium circulation controller7.

The mission oil pump10is arranged at a middle of the mission oil circulating route11. The mission oil pump10pressurizes the mission oil passing through the transmission200to supply again into the transmission200through the microbubble generator4and the ultrasonic wave generator5. The mission oil pump10is activated when the transmission200is activated. That is to say, the mission oil pump10is activated by the output generated by driving the internal combustion engine100.

Next, an operation of the medium circulating apparatus1-3according to the third embodiment is explained.FIG. 9is a control flow chart of the medium circulating apparatus according to the third embodiment. Here, explanations for the operations of the medium circulating apparatus1-3according to the third embodiment that are identical to the operations of the medium circulating apparatus1-1according to the first embodiment are not repeated. The mission oil circulates constantly through the mission oil circulating route11from the start until the stop of the internal combustion engine100since the mission oil pump10is activated by activating the transmission200due to the driving of the internal combustion engine100.

The medium temperature acquiring unit74of the processor72of the medium circulation controller7acquires a temperature T5of the mission oil, which is the medium, while the mission oil circulates through the transmission200by activating the transmission200(step ST301). Specifically, the medium temperature acquiring unit74acquires the temperature T5of the mission oil that circulates through the transmission200. Here, the temperature T5is detected by the mission oil temperature sensor113a, and the temperature T5is outputted to the medium circulation controller7.

Next, the bubble generation controller76of the processor72determines whether the acquired temperature T5of the mission oil is less than or equal to a predetermined value T6or not (step ST302). Here, the temperature T6is a temperature at which the viscosity of the mission oil circulating through the transmission200is high. That is to say, it becomes difficult to start the internal combustion engine100due to the friction at the transmission at the temperature. For example, such temperature is the temperature of the mission oil at the cold start of the internal combustion engine100. The medium temperature acquiring unit74of the processor72repeats to acquire the temperature T5of the mission oil until the acquired temperature T5of the mission oil becomes less than or equal to the predetermined value T6.

Next, the bubble generation controller76of the processor72activates the microbubble generator4when the microbubble generation controller76determines that the temperature T5of the mission oil supplied to the transmission200is less than or equal to the predetermined value T6(step ST303). The microbubbles M are generated since the microbubble generator4is activated, and the generated microbubbles M are mixed into the mission oil, which is the medium (seeFIGS. 2A and 2B). Therefore, the mission oil in which the microbubbles M are mixed can decrease the viscosity, the heat conductivity, and the heat capacity, compared to the mission oil in which the microbubbles M are not mixed.

Next, the ultrasonic wave generation controller77of the processor72activates the ultrasonic wave generator5while the microbubble generator4is activated (step ST304). The ultrasonic wave generator5generates the ultrasonic wave E, and the ultrasonic wave generator5irradiates the mission oil in which the microbubbles M are mixed with the ultrasonic wave E (seeFIG. 3A). The uniformly distributed microbubbles M within the mission oil that are irradiated with the ultrasonic wave E become the small microbubbles M′ by the contraction as shown inFIG. 3B, as well as the microbubbles M break due to the ultrasonic wave E. Therefore, the temperature T5of the mission oil in which the microbubbles M are mixed is uniformly and instantaneously raised.

The mission oil in which the temperature T5is instantaneously raised is supplied into the transmission200with the microbubbles M that are mixed into the mission oil. The mission oil supplied into the transmission200is supplied to the section to be lubricated of the driven part, the section to be driven of the movable part, and the section to be cooled of the heated part, of the transmission200through paths not shown. The heat conductivity and the heat capacity of the mission oil supplied thereto are decreased.

Therefore, the friction caused when the driven part of the transmission200is lubricated can be reduced by the mission oil even if the temperature of the transmission200is low and the temperature of the mission oil is low so that startability of the internal combustion engine100connected to the transmission200can be improved. Further, the medium can hardly receive the heat generated by the transmission200through which the mission oil is circulated even if the temperatures of the transmission200and the mission oil are low whereby the temperature of the transmission200can be raised easily. Therefore, warm up ability of the transmission200can be improved. Startability of the internal combustion engine100and warm up ability of the transmission200can be improved as explained above; therefore, fuel consumption can be improved and degradation of the emission can be suppressed.

In the first, the second, and the third embodiment above, the microbubble generator4can generate the microbubbles M by injecting the mixture of the medium and the gas after mixing the medium and the gas at the bubble generation main body41. Then, the microbubbles M can be mixed into the medium.

Further, in the first, the second, and the third embodiment, it is preferred to start activating the microbubble generator4and the ultrasonic wave generator5immediately before starting the internal combustion engine100. Consequently, the microbubbles M can be mixed into the medium when the medium starts to circulate through the internal combustion engine100or through the transmission200so that the medium in which the microbubbles are mixed can be irradiated with the ultrasonic wave E.

INDUSTRIAL APPLICABILITY

As described above, the medium circulating apparatus according to the present invention is useful for a medium circulating apparatus that circulates at least one of an engine oil, a coolant water, and a mission oil, through an internal combustion engine or through a transmission, and more particularly useful for improving startability and warm up ability of the internal combustion engine.