Vehicle air conditioner with driving mechanism of single hot water valve and plural air mixing doors

In a vehicle air conditioner, a link mechanism, for connecting one of plural driving devices and one of plural air mixing doors to each other is connected to a hot water valve, and is constructed to be operated to first and second maximum cooling positions. At the first maximum cooling position, the one door connected to the link mechanism is operated to a door maximum cooling position, and the valve is opened. At the second position, the door connected to the link mechanism is operated to the door maximum cooling position, and the valve is closed. Therefore, the valve can be suitably opened and closed in accordance with operation positions of the plural air mixing doors without using a dedicated driving mechanism for the valve.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to and claims priority from Japanese Patent Application No. 2001-283610 filed on Sep. 18, 2001, the content of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a driving mechanism of air mixing doors and a single hot water valve for adjusting a flow amount of hot water flowing into a heater core in an air-mixing type vehicle air conditioner.

2. Description of Related Art

In a conventional vehicle air conditioner, an air mixing system is generally used as an air temperature control method. In the air mixing system, a flow amount ratio of hot air heated by a heater core to cool air bypassing the heater core is adjusted by an air mixing door. Further, in the air mixing system, a hot water valve for adjusting a flow amount of hot water (engine cooling water) flowing into the heater core is not required to control an air blowing temperature, but the hot water valve is provided in many cases for the following reasons.

First, in a maximum cooling, an air passage of the heater core is entirely closed by the air mixing door, and a bypass passage through which air bypasses the heater core is entirely opened by the air mixing door. If the hot water valve is not provided in the air mixing system, high-temperature hot water continues to flow into the heater core even in the maximum cooling. Therefore, air around the heater core is heated by the high-temperature hot water in the heater core, and the heated air is mixed into cool air flowing through the bypass passage due to the natural convection. Thus, the air temperature to be blown into a passenger compartment is increased, thereby reducing the maximum cooling performance. Accordingly, in the maximum cooling, the hot water valve is provided to be entirely closed so that high-temperature hot water is prevented from flowing into the heater core.

Secondly, when the hot water valve is not provided, hot water from an engine continues to flow into the heater core even in the maximum cooling. At this time, since the air passage of the heater core is entirely closed by the air mixing door, the hot water returns to the engine without being cooled. Further, because the hot water flows into the heater core, a flow amount of hot water circulated to a radiator for cooling the hot water is reduced, and engine-cooling performance is reduced. When the hot water flowing into the heater core is stopped by entirely closing the hot water valve in the maximum cooling, the amount of hot water flowing into the radiator is increased, thereby increasing the engine-cooling performance.

In a general vehicle air conditioner including a single air mixing door, the air mixing door is simply coupled to the hot water valve so that the hot water valve is entirely closed when the air mixing door is operated at a maximum cooling position. However, in a vehicle air conditioner including plural air mixing doors, since operational positions (open degrees) of the air mixing doors are independently controlled, it is difficult to operatively link the plural air mixing doors and the single hot water valve. For example, in a right-left independent temperature control system, since the operational positions of the right and left air mixing doors are independently controlled, it is difficult to suitably control the operation of the hot water valve in accordance with the operation positions of the right and left air mixing doors.

On the other hand, if a dedicated driving mechanism only for driving the hot water valve is provided separately from the driving mechanism for the air mixing doors, because the dedicated driving mechanism for the hot water valve needs a servomotor and a link mechanism for opening and closing the hot water valve, production cost of a vehicle air conditioner is increased.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above problem, and its object is to suitably open and close a hot water valve in correspondence to operational positions of plural air mixing doors in a vehicle air conditioner.

Its another object is to suitably open and close the hot water valve using a driving mechanism for one air mixing door among the plural air mixing doors without using a dedicated driving mechanism for the hot water valve.

According to the present invention, a vehicle air conditioner includes an air conditioning case defining a plurality of air passages, a heating heat exchanger for heating air in the air passages, a plurality of air mixing doors disposed in the air passages respectively, a hot water valve for adjusting a flow amount of hot water circulated to the heating heat exchanger, a plurality of driving devices for independently driving the air mixing doors, and a link mechanism. The air mixing doors are for adjusting a flow amount ratio of air heated by the heating heat exchanger to air bypassing the heating heat exchanger in the air passages respectively, and the plurality of driving devices are connected to the plurality of air mixing doors respectively. The link mechanism is for connecting one of the driving devices and one of the air mixing doors, and is connected to the hot water valve. In the vehicle air conditioner, the link mechanism is constructed to be operated to a first maximum cooling position where the one air mixing door connected to the link mechanism is positioned at a door maximum cooling position and the hot water valve is opened, and to be operated to a second maximum cooling position where the one air mixing door connected to the link mechanism is positioned at the door maximum cooling position and the hot water valve is closed. Further, when the one air mixing door connected to the link mechanism is operated to the maximum cooling position and an another air mixing door different from the one air mixing door is operated to a position different from the maximum cooling position, the link mechanism is displaced to the first maximum cooling position. On the other hand, when all the air mixing doors are operated at the door maximum cooling positions, the link mechanism is displaced to the second maximum cooling position.

Accordingly, when the link mechanism is operated to the first maximum cooling position, the one air mixing door connected to the link mechanism is operated to the door maximum cooling position and the hot water valve is opened so that a hot-water flow to the heating heat exchanger can be continued. Thus, a control function of the air temperature can be obtained by adjusting an open degree of an air mixing door not connected to the link mechanism in the air passage where the air mixing door not connected to the link mechanism is provided.

Further, when the link mechanism is set at the second maximum cooling position, the hot water valve is closed while the air mixing door connected to the link mechanism is operated at the door maximum cooling position. Accordingly, when all the air mixing doors are operated at the door maximum cooling positions, the hot-water flow to the heating heat exchanger is stopped by closing the hot water valve. Thus, in the maximum cooling, high-temperature hot water can be prevented from continuously flowing into the heating heat exchanger, and it can prevent air heated by the heating heat exchanger from being mixed into cool air due to the natural convection, thereby improving the maximum cooling performance.

Further, when all the air mixing doors are operated to the door maximum cooling positions, the hot-water flow to the heating heat exchanger can be stopped by closing the hot water valve. Therefore, engine cooling performance can be ensured by increasing an amount of hot water circulated into a radiator at an engine side. Furthermore, the hot water valve can be opened and closed by the link mechanism connected to the one of air mixing doors without using a dedicated driving mechanism for the hot water valve, thereby extremely reducing production cost in the vehicle air conditioner.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT

A preferred embodiment of the present invention will be described hereinafter with reference to appended drawings. In this embodiment, the present invention is typically applied to a vehicle air conditioner shown in FIG.1.

In the vehicle air conditioner, as shown inFIG. 1, a ventilation system is constructed so that a temperature of conditioned air to be blown into a space at a driver seat side in a passenger compartment and a temperature of conditioned air to be blown into a space at a front passenger seat side in the passenger compartment can be independently controlled. InFIG. 1, an air conditioning case1defines an air passage through which air flows toward a passenger compartment. The air conditioning case1includes an inside air suction port2and an outside air suction port3at its upstream air side. The inside air suction port2is for sucking air inside the passenger compartment, and the outside air suction port3is for sucking air outside the passenger compartment. The suction ports2,3are selectively opened and closed by an inside-outside air switching door4including a plate door disposed rotatably. The inside-outside air switching door4is driven by a servomotor (not shown) as a driving device to open and close the suction ports2,3.

A centrifugal blower fan5is disposed at a downstream air side of the inside-outside switching door4. The blower fan5is driven to be rotated by a blower motor5aas a driving device. The rotational speed of the blower fan5, that is, the air blowing amount thereof is controlled by a voltage applied to the blower motor5a. The downstream air side of the blower fan5is connected by a connection duct6to an upstream side of an evaporator7disposed in the air conditioning case1. The evaporator7constructs a cooling heat exchanger for cooling air by performing heat-exchange between the air and refrigerant in a refrigerant cycle. Specifically, in the evaporator7, refrigerant absorbs heat from the air so that air passing through the evaporator7is cooled. The evaporator7also constructs the refrigerant cycle together with a condenser, a decompression device, a compressor driven by an engine (not shown), and the like.

In the air conditioning case1, a partition plate8is disposed in the air passage at a downstream side end of the evaporator7. Therefore, the air passage at the downstream air side of the evaporator7in the air conditioning case1is partitioned by the partition plate8into a first air passage9for the driver seat side and a second air passage10for the front passenger seat side. The first air passage9is for introducing conditioned air into the space at the driver seat side (left side inFIG. 1) in the passenger compartment, and the second air passage10is for introducing conditioned air into a space at the front passenger seat side (right side inFIG. 1) in the passenger compartment. InFIG. 1, the present invention is typically applied to a right steering wheel vehicle. A heater core11is disposed at a downstream air side of the evaporator7. Further, the heater core11penetrates through the partition plate8, and protrudes into the first air passage9and the second air passage10. Hot water (cooling water) from the vehicle engine flows into the heater core11, so that air passing through the heater core11is heated by using the hot water as a heat source.

The first air passage9and the second air passage10include bypass passages9a,10awhere air (cool air) flows while bypassing the heater core11, respectively. Air mixing doors12,13are disposed at upstream air sides of the heater core11in the passages9,10, respectively. The air mixing doors12,13include plate doors rotatable about rotation shafts12a,13a, respectively. The air mixing doors12,13are for adjusting flow amount ratios between air flowing through the heater core11and air flowing through the bypass passages9a,10ain the passages9,10, respectively. Therefore, the temperature of conditioned air blown into the passenger compartment from the first air passage9and the temperature of conditioned air blown into the passenger compartment from the second air passage10can be independently controlled. Dedicated servomotors14,15as driving devices are connected to the rotation shafts12a,13aof the air mixing doors12,13through link mechanisms16,17, respectively. The air mixing doors12,13are independently driven by the dedicated servomotors14,15, respectively.

In each of the first and second air passages9,10, hot air passing through the heater core11and cool air passing through the bypass passage9a,10aare mixed at the downstream air side of the heater core11. The mixed air (conditioned air) in the first air passage9is blown toward the drive seat side of the passenger compartment through a driver seat opening portion18, and the mixed air (conditioned air) in the second air passage10is blown toward the front passenger seat side of the passenger compartment through a front passenger seat opening portion19of the air conditioning case1. Each of the opening portions18,19includes a defroster opening, a face opening and a foot opening, and the openings are selectively opened and closed by a blow mode door (not shown). The defroster opening is for blowing conditioned air toward a windshield of the passenger compartment. The face opening is for blowing conditioned air toward the upper half body of a passenger in the passenger compartment, and the foot opening is for blowing conditioned air toward the foot side of the passenger in the passenger compartment.

A hot water valve21is disposed in a hot water pipe20at an inlet side of the heater core11. Hot water flows into the heater core11from the vehicle engine through the hot water pipe20. The hot water valve21is for adjusting an amount of hot water flowing into the heater core11. A valve body (not shown) of the hot water valve21is connected to a link mechanism22. In this embodiment, the link mechanism22is operatively connected to the link mechanism16of the servomotor14of the driver-seat air mixing door12. Therefore, the valve body of the hot water valve21is driven to be opened and closed by the servomotor14through the link mechanisms16,22.

An air-conditioning control unit23(A/C ECU) is for automatically controlling operation of the air conditioner, and has a microcomputer including a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM) and the like. Detection signals are input from sensors to an input side of the air-conditioning control unit23. The sensors include an inside air temperature sensor24for detecting an inside air temperature Tr of the passenger compartment, an outside air temperature sensor25for detecting an outside air temperature Tam, a sunlight sensor26for detecting an amount of sunlight radiated into the passenger compartment, an evaporator temperature sensor27for detecting a temperature (post evaporator temperature) Te of air directly after blown from the evaporator7, a water temperature sensor28for detecting a temperature (hot water temperature) Tw of hot water to flow into the heater core11, and the like. Further, operational signals are input from an air-conditioning operational panel29to the input side of the air-conditioning control unit23. The air-conditioning operational panel29includes operational members such as a driver-seat temperature setting device30and a front passenger-seat temperature setting device31. A driver and a passenger can set their desired temperatures by the driver-seat temperature setting device30and the front passenger-seat temperature setting device31, respectively.

The servomotors14,15of the air mixing doors12,13are electrically connected to an output side of the air-conditioning control unit23. The blower motor5aof the centrifugal blower fan5is electrically connected to the output side of the air-conditioning control unit23through a driving circuit32. A servomotor (not shown) for driving the blow mode door and a servomotor (not shown) for driving the inside-outside air switching door4are also electrically connected to the output side of the air-conditioning control unit23.

An example of the link mechanisms16,22of the servomotor14for driving the drive-seat air mixing door12is shown in FIG.2. InFIG. 2, an output shaft33of the servomotor14is integrated to a bent portion of a driving lever34bent in a V-shape. A pin34ais integrated to one end of the driving lever34. Further, the pin34ais fitted into an engagement slot35aprovided in a driven door lever35to be slidable in the engagement slot35a. One end of the driven door lever35is integrated to the rotation shaft12aof the air mixing door12, so that the rotation shaft12aand the driven door lever35are integrally rotated. A pin34bis integrated to the other end of the driving lever34, and is connected to one end of a connection wire36. The other end of the connection wire36is connected to a driven valve lever37. Specifically, a pin37ais integrated to one end of the driven valve lever37, and is connected to the other end of the connection wire36. The other end of the driven valve lever37is integrated to the rotation shaft21aof the hot water valve21, so that the rotation shaft21aand the driven valve lever37are integrally rotated.

That is, the link mechanism16shown inFIG. 1is constructed by both levers34,35, and the link mechanism22shown inFIG. 1is constructed by the connection wire36and the driven valve lever37. Here, when the hot water valve21is disposed near the air mixing door12, a distance between the output shaft33of the servomotor14and the rotation shaft21aof the hot water valve21can be reduced. Therefore, in this case, a connection member such as a short connection rod can be used in place of the connection wire36.

Next, operation of the vehicle air conditioner according to the above-described embodiment will be described. At first, temperature set signals Tset(Dr), Tset(Pa) are input from the temperature setting devices30,31to the air-conditioning control unit23. Further, detection signals are input from the inside air temperature sensor24, the outside air temperature sensor25, the sunlight sensor26, the evaporator air temperature sensor27and the water temperature sensor28to the air-conditioning control unit23. A target air temperature TAO (Dr) for the driver seat side and a target air temperature TAO (Pa) for the front passenger seat side are calculated based on the input signals. The target air temperature TAO (Dr) is a target temperature of air blown to the driver seat side in the passenger compartment, and the target air temperature TAO (Pa) is a target temperature of air blown to the front passenger seat side in the passenger compartment. Then, a target open degree SW (Dr) of the driver-seat air mixing door12and a target open degree SW (Pa) of the front passenger-seat air mixing door13are calculated based on the target air temperatures TAO (Dr), TAO (Pa), the post evaporator temperature Te, and the water temperature Tw.

Then, operation angles of the servomotors14,15are controlled based on output signals of the air-conditioning control unit23, so that actual open degrees of the air mixing doors12,13are controlled to correspond to the target open degrees SW (Dr), SW (Pa), respectively. Thus, the air temperature from the opening portion18in the first air passage9and the air temperature from the opening portion19of the second air passage10in the air conditioning case1can be controlled at the target air temperatures TAO (Dr), TAO (Pa), respectively. Accordingly, the air temperature for the driver seat side and the air temperature for the front passenger seat side can be automatically maintained at the driver-seat set temperature Tset (Dr) and the front passenger-seat set temperature Tset (Pa), respectively. Here, each open degree of the air mixing doors12,13is calculated as a percentage of 0% at the maximum cooling position and 100% at the maximum heating position. At the maximum cooling positions of the air mixing doors12,13, the air passages of the heater core11are entirely closed, and the bypass passages9a,10aof the heater core11are entirely opened, respectively. On the contrary, at the maximum heating positions of the air mixing doors12,13, the air passages of the heater core11are entirely opened, and the bypass passages9a,10aare entirely closed, respectively. InFIG. 1, the maximum cooling position of the air mixing door12is indicated by the solid line, and the maximum cooling position of the air mixing door13is indicated by the broken line. Further, the maximum heating position of the air mixing door12is indicated by the broken line, and the maximum heating position of the air mixing door13is indicated by the solid line.

Next, coupled operation of the driver-seat air mixing door12and the hot water valve21will be specifically described. As shown inFIG. 3, at step S10, it is determined whether the target open degree SW (Dr) is set at 0% (maximum cooling position). When the target open degree SW (Dr) is set at 0%, it is determined whether the target open degree SW (Pa) is set at 0% at step S20. When the target open degree SW (Pa) is not set at 0%, that is, when the target open degree SW (Pa) is determined to be set at a predetermined intermediate open degree (i.e., open degree in a temperature control area), the operational position of the driving lever34of the link mechanisms16,22is set at a first maximum cooling position C1indicated by a broken line inFIG. 2at step S30. InFIG. 2, by rotating the servomotor14, the driving lever34is rotated about the output shaft33in an entire operational angle θ. A second maximum cooling position C2is located at one end of the entire operational angle θ, and a maximum heating position H is located at the other end of the entire operation angle.

At step S30, the operational position of the servomotor14is set so that the driving lever34is displaced to the first maximum cooling position C1. Here, the first maximum cooling position C1is positioned at the side of the maximum heating position H by a predetermined angle, with respect to the second maximum cooling position C2. That is, the first maximum cooling position C1is positioned between the maximum heating position H and the second maximum cooling position C2, in the entire operation angle θ. When the driving lever34is operated at the first cooling position C1, the driven door lever35is displaced to the solid line position inFIG. 2due to the engagement between the pin34aof the driving lever34and the engagement slot35aof the driven lever35. Accordingly, the driver-seat air mixing door12is moved to the maximum cooling position indicated by the solid line in FIG.2. At this time, the driven valve lever37of the hot water valve21is operated to the broken line position A inFIG. 2by the driving lever34through the connection wire36, and the hot water valve21is opened by a predetermined open degree (corresponding to an open degree α inFIG. 4described later). Therefore, hot water continues to flow into the heater core11, thereby accurately performing an air temperature control of the front passenger-seat air mixing door13in the second air passage10.

On the other hand, when the target open degree SW (Pa) is determined to be set at 0% at step S20, that is, when both of the target open degrees SW (Dr), SW (Pa) are set at 0% (maximum cooling position), the operation angle of the servomotor14is set so that the driving lever34is displaced to the second cooling position C2at step S40. The second maximum cooling position C2is separated from the first maximum cooling position C1by a predetermined angle in a clockwise direction. Here, when the driving lever34is displaced from the first maximum cooling position C1to the second maximum cooling position C2, the pin34aof the driving lever34moves in an idling area of the engagement slot35aof the driven door lever35. Therefore, the driven door lever35is not displaced, but is maintained at the solid line position in FIG.2. Accordingly, the driver-seat air mixing door12is maintained at the maximum cooling position indicated by the solid line in FIG.2. Here, the idling area in the engagement slot35ais formed in an arc shape where the pin34amoves without a movement of the driven door lever35.

When the driving lever34is operated to the second maximum cooling position C2, the driven valve lever37of the hot water valve21is operated to the solid line position in FIG.2through the connection wire36, and the hot water valve21is entirely closed. Therefore, the flow of hot water to the heater core11can be stopped, thereby preventing the temperature of cool air in the maximum cooling from being increased by radiation of hot water in the heater core11in the first air passage9and the second air passage10. Further, the flow amount of engine cooling water (hot water) to the radiator can be increased by stopping the hot-water flow to the heater core11, thereby increasing cooling performance of the radiator. Accordingly, it can prevent the vehicle engine from being supper-heated during cooling operation in summer.

On the other hand, when the target open degree SW (Dr) is not set at 0%, that is, when the target open degree SW (Dr) of the driver-seat air mixing door12is determined to be set in a predetermined intermediate open degree area (open degree in the temperature control area), the driving lever34is operated to an arbitrary position between the first maximum cooling position C1and the maximum heating position H inFIG. 2at step S50. That is, the driving lever34is operated to an arbitrary position corresponding to the target open degree SW (Dr), thereby controlling the air temperature for the driver seat space by controlling the open degree of the driver-seat air mixing door12.

FIG. 4shows changes of open degrees of the driver-seat air mixing door12and the hot water valve21using the link mechanisms16,22. InFIG. 4, the abscissa indicates the operational angle θ of the driving lever34. When the operational angle θ of the driving lever34is set between the first maximum cooling position C1and the second maximum cooling position C2, the open degree of the driver-seat air mixing door12is maintained at 0% (maximum cooling position). At this time, the open degree of the hot water valve21is 0% (entirely closed) at the second maximum cooling position C2, but the open degree of the hot water valve21is the predetermined open degree α at the first maximum cooling position C1. As shown fromFIG. 4, the open degree α of the hot water valve21at the first maximum cooling position C1is set smaller than an open degree when the air passage to the heater core11is opened by the driver-seat air mixing door12. That is, when the operational angle θ of the driving lever34is set between the first maximum cooling position C1and the maximum heating position H, the open degree of the hot water valve21is larger than the open degree α of the hot water valve21at the first maximum cooling position C1.

For example, the present invention can be applied to various air conditioning systems without being limited to the above-described embodiment. In the above-described embodiment, the driver-seat air mixing door12is coupled to the hot water valve21by the link mechanisms16,22. However, the passenger-seat air mixing door13may be coupled to the hot water valve21by the same link mechanisms as the link mechanisms16,22.

Further, the present invention can be applied to a vehicle air conditioner with a front-rear independent temperature control system where an air temperature for a space at a front seat side and an air temperature for a space at a rear seat side of the passenger compartment are independently controlled, without being limited to the right-left independent temperature control system as in the above-described embodiment. Further, the present invention can be applied to a manual control system where the air mixing doors12,13are manually controlled, without being limited to a system where the air mixing doors12,13are driven by a driving device such as a servomotor as in the above-described embodiment. In this case, the link mechanism of the air mixing doors12,13is connected to a manual operation member provided on the air-conditioning operation panel. That is, a driving device for driving the air mixing doors12,13is constructed by a manual operation mechanism.

In the above-described embodiment, the maximum cooling positions of the air mixing doors12,13are set in the states where the bypass passages9a,10aare entirely opened and the air passages to the heater core11are entirely closed by the air mixing doors12,13, respectively. However, the maximum cooling positions may be set in predetermined areas including states where the air passages to the heater core11are opened by very small amounts, respectively. Further, the present invention may be applied to a vehicle air conditioner including three ore more air mixing doors without being limited to the two air mixing doors12,13as in the above-described embodiment. The air mixing doors12,13may be another type door such as a film door without being limited to the plate door shown inFIGS. 1,2.