Vehicular cooling device

Abstract

To highly accurately estimate a temperature of cooling liquid used for a power transmission device and improve cooling performance by controlling cooling means without excess and deficiency on the basis of the temperature.SOLUTION: A vehicular cooling device 10 includes: an engine (prime mover) 1; a belt type continuously variable transmission (power transmission device) 3 that is cooled by cooling liquid and transmits driving force of the engine 1; and a plurality of cooling means for cooling the belt type continuously variable transmission 3. The vehicular cooling device further includes: power transmission device thermal balance acquisition means 31 for acquiring thermal balance of the belt type continuously variable transmission 3; cooling thermal balance acquisition means 32 for acquiring cooling thermal balance of the cooling means; and cooling means control means 30 for controlling the cooling means. The cooling means control means 30 estimates a cooling liquid temperature Tp after a predetermined time t of a cooling liquid temperature T on the basis of the thermal balance of the belt type continuously variable transmission 3 and the cooling thermal balance of the cooling means, and controls the cooling means only when the cooling liquid temperature Tp exceeds an upper limit temperature Tc (Tp>Tc).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle cooling system that estimates the temperature of a coolant used in a vehicle's power transmission system by heat balance, and selects and controls a cooling means based on the estimated value. [Background technology]

[0002] Conventionally, vehicle power transmission devices, including transmissions, use a coolant (ATF: Automatic Transmission Fluid) to cool and lubricate their internal components, but the temperature of this coolant rises as the vehicle absorbs and generates heat. Vehicle power transmission devices include planetary-type stepped automatic transmissions, belt-type continuously variable transmissions (CVTs), dual-clutch transmissions, manual transmissions, hybrid drive systems, and gearboxes for electric vehicles.

[0003] However, if the temperature of the coolant rises above a predetermined temperature (upper limit temperature) as the vehicle is running, the power transmission device will not be able to maintain its performance due to insufficient cooling or lubrication, so it is necessary to prevent the temperature of the coolant from rising above the predetermined temperature (upper limit temperature).

[0004] For example, Patent Document 1 proposes an oil temperature control device that can appropriately control the temperature (oil temperature) of the coolant in a vehicle power transmission (transmission). This oil temperature control device is equipped with a flow control unit that controls the flow rate of the coolant (lubricating oil) supplied to a heat exchanger, and this flow control unit controls the flow rate of the coolant supplied to the heat exchanger based on the amount of heat generated by transmission loss.

[0005] Furthermore, Patent Document 2 proposes an oil temperature estimation device that estimates the oil temperature of a transaxle in a hybrid vehicle using an inexpensive system without using a temperature sensor. Specifically, this oil temperature estimation device includes a heat generation amount calculation unit that calculates the amount of heat generated due to torque loss in each power transmission path divided within the transaxle, and this heat generation amount calculation unit calculates the heat generation amount in the transaxle by adding the heat generation amounts in the power transmission paths in a selected driving mode, and estimates the temperature of the lubricating oil in the transaxle based on this heat generation amount. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5272800 [Patent Document 2] Japanese Patent Application Publication No. 2022-148469 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the oil temperature control device proposed in Patent Document 1, when the power transmission device generates a large amount of heat, it is conceivable that cooling may be insufficient simply by controlling the flow rate of the coolant in the heat exchanger. For this reason, it is common for a drive system to have multiple cooling means. However, excessive operation of each cooling means may result in reduced fuel efficiency, increased noise and vibration (NV), and reduced acceleration and driving performance. Therefore, it is necessary to avoid excessive cooling and minimize cooling by unnecessary cooling means. There is also a desire to minimize the use of cooling means that are thought to have a large impact, as described above, and to prioritize the use of cooling means that have a relatively small impact.

[0008] Furthermore, the oil temperature estimating device proposed in Patent Document 2 only estimates the oil temperature of the transaxle, and does not control cooling means or the like based on the estimated oil temperature.

[0009] The present invention has been made in consideration of the above circumstances, and its purpose is to provide a vehicle cooling device that can accurately estimate the temperature of the coolant used in the power transmission device and the heat balance of the power transmission device, and can control the cooling means based on the temperature and heat balance so that it is neither too much nor too little, and without causing a decrease in the vehicle's economy or riding feel, thereby improving cooling performance. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention provides a vehicle cooling device (10) mounted on a vehicle having a prime mover (1) cooled by cooling water, a power transmission device (3) cooled by a coolant and transmitting the driving force of the prime mover (1), and a plurality of cooling means for cooling the power transmission device (3), the vehicle cooling device (10) comprising: a power transmission device heat balance acquisition means (31) for acquiring the heat balance of the power transmission device (3); a cooling heat balance acquisition means (32) for acquiring the cooling heat balance of the cooling means; and a cooling means control means (30) for controlling the cooling means, wherein the cooling means control means (30) selects a cooling means to be used from the plurality of cooling means based on the heat balance of the power transmission device (3) acquired by the power transmission device heat balance acquisition means (31) and the cooling heat balance of the cooling means acquired by the cooling heat balance acquisition means (32), and controls the selected cooling means.

[0011] Here, the cooling means control means (30) controls the cooling means only when a predicted coolant temperature (Tp) predicted from the coolant temperature (T) and the heat balance exceeds an upper limit value (Tc) of the coolant temperature.

[0012] The power transmission device heat balance acquisition means (31) acquires the heat generation amount (Wc) based on the operation of the power transmission device (3), the surface heat radiation amount (Wa) of the power transmission device (3), and the heat radiation amount (W LSpecifically, the power transmission device heat balance acquisition means (31) acquires the heat balance of the power transmission device (3) from at least one of information on the rotation speed of the prime mover (1), the torque of the prime mover (1), the coolant temperature, the vehicle speed, and the coolant temperature.

[0013] Furthermore, the cooling heat balance acquisition means (32) acquires the heat balance of the cooling means from at least one piece of information including the rotation speed of the prime mover (1), the torque of the prime mover (1), the coolant temperature, the vehicle speed, and the coolant temperature.The cooling means control means (30) then selects, as the cooling means to be used, one that minimizes the cooling heat balance by exceeding the required heat amount determined from the heat balance. Alternatively, the cooling means control means (30) selects, as the cooling means to be used, a combination of one or more cooling means that minimizes the cooling heat balance by exceeding the required heat amount determined from the heat balance.

[0014] Furthermore, the cooling means each have an evaluation score related to vehicle economy and riding comfort, and the cooling means control means (30) selects, as the cooling means to be used, one or a combination of the cooling means in which the cooling heat balance exceeds the required heat amount obtained from the heat balance and the evaluation score is the smallest. Alternatively, the cooling means control means (30) calculates the evaluation score of each of the cooling means from information obtained from the vehicle running state, and selects, as the cooling means to be used, one or a combination of the cooling means in which the cooling heat balance exceeds the required heat amount obtained from the heat balance and the evaluation score is the smallest. Then, the cooling means control means (30) changes the selection method for the cooling means to be used based on the running mode selected by the driver.

[0015] Here, the first cooling means, which is one of the cooling means, operates the opening and closing part (13), the second cooling means controls the rotation speed of the radiator fan (14), the third cooling means controls the rotation speed of the prime mover (1), the fourth cooling means changes the gear ratio of the automatic transmission (3) in a direction that improves the efficiency of the automatic transmission (3) while keeping the output of the prime mover (1) and the vehicle speed constant, and the fifth cooling means reduces the output of the prime mover (1).

[0016] The prime mover (1) may be an engine, and the power transmission device (3) may be a belt-type continuously variable transmission. [Effects of the Invention]

[0017] According to the present invention, the cooling means control means estimates with high accuracy the temperature of the coolant used in the power transmission device based on the heat balance of the power transmission device acquired by the power transmission device heat balance acquisition means and the cooling heat balance of the cooling means acquired by the cooling heat balance acquisition means, and controls the cooling means just enough only when the estimated coolant temperature is expected to exceed the upper limit temperature, thereby preventing the coolant temperature from exceeding the upper limit temperature, thereby achieving the effect of improving cooling performance without reducing the vehicle's economy or riding feel. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram showing a schematic configuration of a vehicle cooling device according to the present invention and a power transmission system of a vehicle equipped with the same; [Figure 2] FIG. 2 is a configuration diagram of a cooling means control unit (TCU). [Figure 3] FIG. 4 is a control block diagram of the coolant temperature. [Figure 4] FIG. 4 is a diagram showing the change in coolant temperature over time using the vehicle running load as a parameter. [Figure 5] FIG. 10 is a diagram showing, in tabular form, the cooling effect of various cooling means, the economy of the vehicle, and the riding feeling. [Figure 6]FIG. 4 is a diagram showing changes in power transmission efficiency with respect to the gear ratio of a belt-type continuously variable transmission. [Figure 7] 3 is a diagram showing the heat balance of the power transmission device and the cooling heat balance of each cooling means; FIG. [Figure 8] 10 is a diagram showing the heat balance of the power transmission device and the cooling heat balance of a cooling means and a plurality of combined cooling means. FIG. [Figure 9] FIG. 10 is a diagram showing the evaluation scores of each cooling means and a plurality of cooling means combined together. [Figure 10] 1 is a diagram schematically illustrating a configuration of a vehicle cooling device according to the present invention when applied to a hybrid vehicle, and a power transmission system of the vehicle equipped with the same; DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0020] [Vehicle power transmission system configuration] First, the configuration of a vehicle cooling device according to the present invention and a power transmission system of a vehicle equipped with the same will be described with reference to Fig. 1. In Fig. 1, the directions indicated by arrows are the "front of the vehicle" and the "rear of the vehicle," respectively.

[0021] As shown in Fig. 1, an engine 1 is mounted at the front of the vehicle as a prime mover that is a drive source, and a belt-type continuously variable transmission (CVT) 3 that is a transmission is connected to the engine 1. Here, the engine 1 is an internal combustion engine such as a gasoline engine, but it may also be a diesel engine.

[0022] Although not shown, the belt-type continuously variable transmission (CVT) 3 is configured by wrapping an endless metal belt around a drive pulley on the driving side and a driven pulley on the driven side. By adjusting the axial thrust acting on the drive pulley and the driven pulley, the winding diameter of the metal belt around these drive pulley and driven pulley is changed, thereby continuously changing the gear ratio. A coolant (ATF) flows inside the belt-type continuously variable transmission (CVT) 3 to lubricate and cool various components and drive the drive pulley and driven pulley. The vehicle cooling device 10 according to the present invention cools this coolant and keeps its temperature (coolant temperature) below a predetermined set value (hereinafter referred to as the "upper limit temperature"). Details of this will be described later.

[0023] Therefore, the rotation of the engine 1 is changed in speed by a belt-type continuously variable transmission (CVT) 3 and transmitted to the drive shaft 4. The rotation of the drive shaft 4 is transmitted to a pair of left and right drive wheels (not shown) attached to the drive shaft 4 via a differential mechanism (not shown), thereby allowing the vehicle to travel at a predetermined speed.

[0024] [Cooling system configuration] Next, the configuration of a vehicle cooling device 10 according to the present invention will be described with reference to FIG.

[0025] The engine 1 reaches high temperatures due to the heat generated by combustion of fuel such as gasoline and friction between sliding parts such as pistons, and is therefore cooled by cooling water flowing through a water jacket (not shown) formed inside the engine 1. The temperature of the coolant (ATF) inside the belt-type continuously variable transmission (CVT) 3 rises due to frictional heat and agitation generated in various parts, and if that temperature (coolant temperature) exceeds a predetermined value, the cooling and lubricating performance of the coolant will decrease, so the coolant is cooled by heat exchange with cooling water (LLC: Long Life Coolant).

[0026] A radiator 11, which is a heat exchanger, is located in front of the engine 1 at the front of the vehicle. In front of this radiator 11 are a grill 12 through which the wind generated when the vehicle is moving passes, and a shutter grill 13 which adjusts the opening area of ​​this grill 12 to control the volume of the wind. Behind the radiator 11 is a radiator fan 14 which draws in outside air including the wind and promotes heat exchange between the outside air and the coolant in the radiator 11.

[0027] Here, the shutter grill 13 is opened and closed by an electric actuator (not shown) to adjust the opening area of ​​the grill 12, and this shutter grill 13 is electrically connected to a transmission control unit (hereinafter abbreviated as "TCU") 30 which serves as a coolant cooling means control device, and its operation is controlled by the TCU 30. Also, the radiator fan 14 is driven to rotate by an electric motor 15, and this electric motor 15 is electrically connected to the TCU 30, and its rotation is controlled by the TCU 30.

[0028] The belt-type continuously variable transmission (CVT) 3 is also provided with a heat exchanger (CVT warmer) 20, and as will be described later, cooling water and coolant flow through this heat exchanger 20. As a result, the coolant is cooled by the cooling water through heat exchange between them.

[0029] The coolant circulates through a water-cooled circuit 17 including the radiator 11. The water-cooled circuit 17 is configured as a closed circuit including a water pipe a that guides the coolant, which has cooled the engine 1 and reached a high temperature, to an inlet of a heat exchanger 20, a water pipe b that guides the coolant that has been subjected to heat exchange with the coolant in the heat exchanger 20, to an electric water pump 18, a water pipe c that guides the coolant discharged from the electric water pump 18 to the inlet of the radiator 11, and a water pipe d that guides the coolant cooled by the radiator 11 and flowing out of the outlet of the radiator 11 to a mechanical water pump 16. A water temperature sensor 19 that detects the temperature of the coolant (coolant temperature) is provided in the water pipe a, and is electrically connected to the TCU 30. The coolant temperature detected by the water temperature sensor 19 is transmitted to the TCU 30. The mechanical water pump 16, which is an auxiliary device of the engine 1, is driven by part of the power of the engine 1. Furthermore, even when either the electric water pump 18 or the mechanical water pump 16 is not operating, the water cooling circuit 17 continues to function by operating the other water pump via a bypass circuit (not shown).

[0030] The coolant circulates through a liquid cooling circuit 21 that forms a closed circuit. This liquid cooling circuit 21 is made up of a liquid pipe e that extends from the outlet of the heat exchanger 20 and is connected to the inlet of the heat exchanger 20. This liquid pipe e is provided with an electric liquid pump 22 that circulates the coolant, a liquid temperature sensor 23 that is a coolant temperature acquisition means that detects the coolant temperature, and a mechanical liquid pump 24 that is driven by part of the power of the engine 1. The electric liquid pump 22 is electrically connected to the TCU 30, and its operation is controlled by the TCU 30. The liquid temperature sensor 23 is also electrically connected to the TCU 30, and the coolant temperature detected by the liquid temperature sensor 23 is sent to the TCU 30.

[0031] [Cooling device function] Next, the operation of the vehicle cooling device 10 configured as above will be described below.

[0032] While the engine 1 is operating, the coolant is circulated through a water-cooled circuit 17 by an electric water pump 18 and a mechanical water pump 16 driven by part of the power of the engine 1 to cool the engine 1, and the coolant is also cooled by heat exchange with the coolant circulating in a liquid-cooled circuit 21. That is, the coolant, which has become hot by flowing through a water jacket (not shown) of the engine 1 to cool the engine 1, is guided through water pipe a of the water-cooled circuit 17 to a heat exchanger 20, where it is cooled by heat exchange with the coolant flowing in the liquid-cooled circuit 21. After that, the coolant is supplied to the electric water pump 18 through pipe b, and after being pressurized by the electric water pump 18, is guided to the radiator 11 through pipe c. In the radiator 11, outside air passes through the radiator 11 via the grille 12 by a radiator fan 14 rotated by an electric motor 15, and in the radiator 11, the coolant is cooled by heat exchange with the outside air (traveling wind when the vehicle is traveling) passing through the radiator 11, thereby lowering its temperature. The flow rate of the outside air passing through the grille 12 is adjusted by opening and closing the shutter grille 13. That is, the opening and closing of the shutter grille 13 is controlled by the TCU 30 to adjust the opening area of ​​the grille 12, and the flow rate of the outside air (traveling wind) passing through the grille 12 is controlled by adjusting the opening area of ​​the grille 12.

[0033] As described above, the coolant, which has been cooled by passing through the radiator 11 and has a lowered temperature, is guided from the radiator 11 through the water pipe d to the mechanical water pump 16, and is then introduced into the engine 1 by the mechanical water pump 16 and cools the engine 1 as it flows through a water jacket (not shown) inside the engine 1. In the liquid-cooling circuit 21, the coolant is circulated by the electric liquid pump 22 and the mechanical liquid pump 24, and the temperature of this coolant is detected by the liquid temperature sensor 23, and the detection result is sent to the TCU 30. In addition, the temperature of the coolant flowing through the water pipe a of the water-cooling circuit 17 (coolant temperature) is detected by the water temperature sensor 19, and the detection result is sent to the TCU 30.

[0034] The above-described actions are continuously repeated, and the engine 1 is cooled by the cooling water, and the cooling liquid inside the belt-type continuously variable transmission (CVT) 3 is cooled by the cooling water, thereby keeping the temperature of the cooling liquid below a certain value.

[0035] [Coolant temperature control method] Next, a method for controlling the coolant temperature in the vehicle cooling device 10 according to the present invention configured as above will be described below with reference to FIGS.

[0036] In this embodiment, the following five cooling means are employed to cool the coolant that flows through the heat exchanger 20 and circulates through the liquid cooling circuit 21. 1) Cooling means 1 (first cooling means): operating the shutter grill 13 2) Cooling means 2 (second cooling means): Controls the rotation speed of the radiator fan 14 3) Cooling means 3 (third cooling means): Controls the rotation speed of engine 1 4) Cooling means 4 (fourth cooling means): Changes the speed ratio of the belt-type continuously variable transmission 3 5) Cooling means 5 (fifth cooling means): Reduces the output of engine 1

[0037] In this embodiment, the TCU 30, which is a cooling means control device, estimates the cooling liquid temperature (referred to as the "estimated temperature") Tp (see Figure 4) a predetermined time t after the time when the cooling liquid temperature T is acquired (detected) by the liquid temperature sensor 23, based on the heat balance of the belt-type continuously variable transmission 3, and if this estimated liquid temperature Tp exceeds the upper limit temperature Tc (see Figure 4), selects one or more cooling means to be adopted from the first to fifth cooling means based on the cooling heat balance of each of the cooling means 1 to 5 and the evaluation scores of each of the first to fifth cooling means, and performs control to cool the cooling liquid using the selected cooling means to keep its temperature (cooling liquid temperature) below the upper limit temperature Tc.

[0038] Here, as shown in FIG. 2, the TCU 30 is equipped with a power transmission device heat balance acquisition means 31 that acquires (calculates) the heat balance of the belt-type continuously variable transmission 3, which is the power transmission device, and a cooling heat balance acquisition means 32 that acquires (calculates) the cooling heat balance of each of the cooling means 1 to 5. These power transmission device heat balance acquisition means 31 and cooling heat balance acquisition means 32 acquire (calculate) the heat balance of the belt-type continuously variable transmission 3 and the cooling heat balance of each of the cooling means 1 to 5 based on the engine speed detected by the rotation sensor 41, which is the prime mover speed acquisition means, the estimated engine torque calculated from the amount of intake air to the prime mover, etc., the coolant temperature (coolant temperature) detected by the water temperature sensor 19, which is the prime mover coolant temperature acquisition means, the coolant temperature detected by the liquid temperature sensor 23, which is the power transmission device coolant temperature acquisition means, and the vehicle speed detected by the vehicle speed sensor 43.

[0039] Thus, the power transmission device heat balance acquisition means 31 calculates the heat generation amount Wc based on the operation of the belt-type continuously variable transmission 3, the surface heat radiation amount Wa of the belt-type continuously variable transmission 3, and the heat radiation amount W of the heat exchanger 20 (the amount of heat exchanged between the coolant and the cooling water) L Here, if the amount of heat stored and released in the belt-type continuously variable transmission 3 is ΔW, the amount of heat stored and released ΔW, the amount of heat generated by the belt-type continuously variable transmission 3 Wc, the amount of heat released from the surface Wa, and the amount of heat released from the heat exchanger 20 W L The following relation holds between Wc-(W L +Wa)+ΔW=0 …(1) However, when the coolant temperature is saturated, ΔW=0, so equation (1) becomes: Wc-(W L +Wa)=0 Wc=W L +Wa …(2) The heat generation amount Wc of the belt-type continuously variable transmission 3 is calculated by multiplying the heat radiation amount W of the heat exchanger 20 by the heat generation amount Wc of the belt-type continuously variable transmission 3 by the heat generation amount Wc of the heat exchanger 20. L and the surface heat dissipation amount Wa of the belt-type continuously variable transmission 3 (W L +Wa) (balance).

[0040] Here, the estimation of the coolant temperature by TCU30, the determination of whether or not to control the coolant temperature based on the estimated coolant temperature (predicted coolant temperature) Tp, the method of selecting which cooling means to use from cooling means 1 to 5 when controlling the coolant temperature, and the action of the selected cooling means will be described below with reference to Figures 3 to 5.

[0041] (Estimation of coolant temperature) 4 shows the change in coolant temperature over time using the vehicle's driving load as a parameter, with solid line A showing the estimated change in coolant temperature over time at high load, dashed line B showing the estimated change in coolant temperature at medium load, and dashed two-dot line C showing the estimated change in coolant temperature over time at low load. The current coolant temperature T acquired (detected) by the coolant temperature sensor 23 shown in FIG. 1 rises rapidly over time at high load, as shown by solid line A, and rises slowly over time at low load, as shown by dashed two-dot line C, without exceeding the upper limit temperature Tc. Furthermore, at medium load, the rate at which the current coolant temperature T rises over time is intermediate between that at high load and that at low load, as shown by dashed two-dot line B.

[0042] Therefore, as shown in FIG. 3, the power transmission device heat balance acquisition means 31 (see FIG. 2) provided in the TCU 30 calculates the heat generation amount Wc of the belt-type continuously variable transmission 3 based on vehicle information such as the engine speed detected by the rotation sensor 41 (see FIG. 2) and the engine torque calculated from the amount of air intake into the engine 1, while taking into account the power transmission efficiency (see FIG. 6) of the belt-type continuously variable transmission 3 (step S1 in FIG. 3).

[0043] Further, the power transmission device heat balance acquisition means 31 calculates the heat release amount (heat exchange amount of the coolant with the coolant) W of the heat exchanger 20 based on the coolant temperature detected by the water temperature sensor 19 (see FIGS. 1 and 2) and the coolant temperature detected by the liquid temperature sensor 23 (see FIGS. 1 and 2), taking into account the flow rates of the coolant and the coolant in the heat exchanger 20, and the density and specific heat of the coolant. L is calculated (step S2 in FIG. 3).

[0044] Furthermore, the power transmission device heat balance acquisition means 31 calculates the surface heat dissipation amount Wa of the belt-type continuously variable transmission 3 based on the coolant temperature detected by the water temperature sensor 19 (see Figures 1 and 2), the coolant temperature detected by the liquid temperature sensor 23, and the vehicle speed detected by the vehicle speed sensor 43 (see Figure 2), taking into account the heat dissipation rate of the belt-type continuously variable transmission 3, a temperature correction coefficient, and a wind speed correction coefficient (step S3 in Figure 3).

[0045] As described above, the heat generation amount Wc of the belt-type continuously variable transmission 3, the surface heat radiation amount Wa, and the heat radiation amount W of the heat exchanger 20 L When the above is calculated, the TCU 30 calculates the heat generation amount Wc of the belt-type continuously variable transmission 3, the surface heat radiation amount Wa, and the heat radiation amount W of the heat exchanger 20 while taking into account the heat capacity of the belt-type continuously variable transmission 3. L Based on this, the coolant temperature Tp (hereinafter referred to as "estimated coolant temperature") is estimated a predetermined time t after the point (present) when the coolant temperature T is detected by the coolant temperature sensor 23 (step S4 in FIG. 3).

[0046] The estimated fluid temperature Tp calculated through the above process varies depending on the vehicle's running load, as shown in FIG. 4. In the illustrated example, the estimated fluid temperature Tp at high load, indicated by solid line A, is higher than the upper limit temperature Tc (Tp>Tc). In contrast, the estimated fluid temperature Tp at low load, indicated by two-dot chain line C in FIG. 4, is lower than the upper limit temperature Tc (Tp <Tc)。

[0047] Therefore, when the coolant temperature Tp is estimated as the coolant temperature a predetermined time t after the time (present) when the coolant temperature T is detected by the coolant temperature sensor 23 based on the heat balance of the belt-type continuously variable transmission 3 (step S4 in FIG. 3), it is determined whether or not this estimated coolant temperature Tp exceeds the upper limit temperature Tc (step S5 in FIG. 3). For example, as shown by the solid line A in FIG. 4, when the estimated coolant temperature Tp exceeds the upper limit temperature Tc (Tp>Tc) (step S4: Yes), such as during high-load operation of the vehicle, a coolant temperature control execution instruction is output from the TCU 30 (step S6 in FIG. 3).

[0048] On the other hand, for example, as shown by the two-dot chain line C in FIG. 4, when the estimated coolant temperature Tp does not exceed the upper limit temperature Tc (Tp < Tc), such as during low-load operation of the vehicle (step S5: No), the process returns to the beginning (step S7 in FIG. 3), and thereafter, the same process is repeated.

[0049] (Coolant Temperature Control) When the estimated coolant temperature Tp exceeds the upper limit temperature Tc (Tp > Tc) (step S5: Yes), and an instruction to execute coolant temperature control is output from the TCU 30 (step S6 in FIG. 3), the amount of heat required to suppress the coolant temperature below the upper limit temperature Tc is calculated (step S8 in FIG. 3). Although the cooling heat balance of each of the cooling means 1 to 5 is calculated by the cooling heat balance acquisition means 32 shown in FIG. 2, since these cooling heat balances are calculated in the same manner as the heat balance of the belt-type continuously variable transmission 3, the description thereof is omitted here. Here, the cooling heat balances calculated for each of the cooling means 1 to 5 are shown in a bar graph format in FIG. 7 together with the required amount of heat (the amount of heat required to suppress the coolant temperature below the upper limit temperature Tc, which is obtained from the heat balance and may be the same amount as the heat balance). As shown in the same figure, the cooling heat balances of each of the cooling means 1 to 5 increase in the order of cooling means 1 → cooling means 2 → cooling means 3 → cooling means 4 → cooling means 5. And the cooling heat balances of cooling means 3 to 5 show values higher than the required amount of heat.

[0050] Also, FIG. 8 shows, in a bar graph format, the cooling heat balances of each of the cooling means 1 to 5, the combination of cooling means 1 and 2 (cooling means 1 + 2), the combination of cooling means 1 and 3 (cooling means 1 + 3), and the combination of cooling means 1, 2, and 3 (cooling means 1 + 2 + 3) together with the required amount of heat. As shown in the same figure, the cooling heat balances in the combination of cooling means 1 and 2 (cooling means 1 + 2), the combination of cooling means 1 and 3 (cooling means 1 + 3), and the combination of cooling means  1, 2, and 3 (cooling means 1 + 2 + 3) all show values larger than the required amount of heat, and increase in the order of cooling means 1 + 2 → cooling means 1 + 3 → cooling means 1 + 2 + 3.

[0051] Thus, as described above, once the cooling heat balance of each of the cooling means 1 to 3 is calculated, the amount of heat required to keep the coolant temperature below the upper limit temperature Tc (see FIG. 4) is calculated (step S8 in FIG. 3), and the amount of cooling heat of each of the cooling means 1 to 5 is calculated (step S9 in FIG. 3). Then, the cooling means to be used is selected based on the above calculation results, or on the calculation results combined with evaluation scores set for each of the cooling means 1 to 5, which will be described later (step S10 in FIG. 3). Here, the evaluation scores are set for each of the cooling means 1 to 5 in relation to the economy (fuel economy) and riding comfort (noise and vibration) of the vehicle, and are calculated based on information obtained from the running state of the vehicle.

[0052] Here, the cooling parameter changes, cooling effect, economy, and riding feeling for each of the cooling means 1 to 5 are summarized in a table in Fig. 5. Each of the cooling means 1 to 5 will be explained below.

[0053] (1) Cooling means 1: When the shutter grill 13 (see FIG. 1) which is the cooling means 1 is operated (opened), the opening area of ​​the grill 12 shown in FIG. 1 increases, and the cooling parameters change as follows: 1) Decrease in cooling water temperature 2) Increased cooling airflow The cooling effect is as follows: 1) Increase in heat exchange amount of heat exchanger 20 2) Increased heat dissipation from the belt-type continuously variable transmission 3 case However, in terms of economy, there is a possibility that fuel efficiency will decrease due to a deterioration in aerodynamic performance.

[0054] (2) Cooling means 2: When the rotation speed of the radiator fan 14 (see FIG. 1), which is the cooling means 2, is increased, the amount of outside air (cooling air volume) guided to the radiator 11 shown in FIG. 1 increases, and the changes in the cooling parameters and the cooling effect are the same as those of the cooling means 1, but the rotation of the fan may worsen NV (noise and vibration), which may affect the riding feel of the vehicle.

[0055] (3) Cooling means 3: When the operation of increasing the engine speed, which is the cooling means 3, is performed, the following changes in the cooling parameters are made: 1) Increase in cooling water flow rate The cooling effect is as follows: 1) Increase in the amount of heat exchanged in the heat exchanger 20 On the other hand, in terms of economy and riding feel, the increase in engine 1 rotation speed may result in a deterioration in fuel economy and NV (noise and vibration).

[0056] (4) Cooling means 4: An operation is performed to change the speed ratio of the belt-type continuously variable transmission 3 (see FIG. 1), which is the cooling means 4. Here, Fig. 6 shows the change in power transmission efficiency of the belt-type continuously variable transmission 3 with respect to the speed ratio when the engine output is constant. As shown in the figure, the power transmission efficiency of the belt-type continuously variable transmission 3 is highest when the speed ratio is 1, and it can be seen that the power transmission efficiency decreases as the speed ratio becomes smaller than 1 and as the speed ratio becomes larger than 1.

[0057] Therefore, when the belt-type continuously variable transmission 3 is operated so that the speed ratio of the belt-type continuously variable transmission 3 approaches 1, the cooling parameters change as shown in FIG. 5 . 1) Improvement of power transmission efficiency of belt-type continuously variable transmission 3 The cooling effect is as follows: 1) Reduction of heat generation from the belt-type continuously variable transmission 3 However, in terms of economy and riding feel, the increase in engine speed may lead to a deterioration in fuel economy and NV.

[0058] (1) Cooling means 5: When an operation to reduce the output of the engine 1 (see FIG. 1 ) which is the cooling means 5 is performed, the cooling parameters are changed as follows: 1) Reduction of drive loss in the belt-type continuously variable transmission 3 2) Decrease in cooling water temperature The cooling effect is as follows: 1) Reduction of heat generation from the belt-type continuously variable transmission 3 2) Increase in heat exchange amount of heat exchanger 20 However, in terms of riding comfort, the driving performance of the vehicle may be deteriorated due to a decrease in the driving force of the engine 1.

[0059] Incidentally, the evaluation scores for each of the cooling means 1 to 5 shown in Fig. 5 were calculated as shown in Fig. 9. Fig. 9 shows the evaluation scores for each of the cooling means 1 to 5, as well as the evaluation scores for a combination of cooling means 1 and cooling means 2 (cooling means 1+2), a combination of cooling means 1 and cooling means 3 (cooling means 1+3), and a combination of cooling means 1, cooling means 2, and cooling means 3 (cooling means 1+2+3). According to the figure, the evaluation scores for cooling means 1 to 5 increase in the order of cooling means 1 → cooling means 2 → cooling means 3 → cooling means 4 → cooling means 5, with cooling means 5 having the highest evaluation score.

[0060] Furthermore, for the combination of cooling means 1 and cooling means 2 (cooling means 1+2), the combination of cooling means 1 and cooling means 3 (cooling means 1+3), and the combination of cooling means 1, cooling means 2, and cooling means 3 (cooling means 1+2+3), the evaluation scores increase in the order of cooling means 1+2 → cooling means 1+3 → cooling means 1+2+3, but these evaluation scores are higher than the evaluation scores of cooling means 1 to 3, and lower than the evaluation scores of cooling means 4 and 5.

[0061] When selecting the cooling means to be used from cooling means 1 to 5 or combinations of these cooling means, cooling means 1+2, cooling means 1+2, and cooling means 1+2+3 (step S10 in FIG. 3), one of the following three methods is used for the selection. 1) First choice method: The first selection method is a method of selecting a cooling means that has a cooling heat balance that exceeds the required heat amount and is the smallest, without considering the combination of cooling means. In this embodiment, cooling means 3 is selected, as shown in Figure 7.

[0062] 2) Second choice method: The second selection method is a method of selecting cooling means, including the combination of cooling means, such that the cooling heat balance exceeds the required heat amount and is minimized. In this embodiment, as shown in Figure 8, a combination of cooling means 1 and cooling means 2 (cooling means 1+2) is selected.

[0063] 3) The third option: The third selection method is a method of selecting a cooling means, including a combination of cooling means, such that the cooling heat balance exceeds the required heat amount and the number of evaluation points is minimized. In this embodiment, cooling means 3 is selected, as shown in Figure 9.

[0064] As described above, cooling means 3 is selected by the first and third selection methods, or a combination of cooling means 1 and cooling means 2 (cooling means 1+2) is selected by the second selection method (step S10 in Figure 3), and the selected cooling means properly controls the coolant temperature without excess or deficiency, so that the coolant temperature can be kept below the upper limit temperature Tc, as shown by the dashed line D in Figure 4, and deterioration of the coolant performance due to temperature rise can be effectively prevented.

[0065] Furthermore, by controlling the coolant temperature using the cooling means 3 selected by selection method 3, the evaluation score can be minimized, thereby achieving the effect of controlling the coolant temperature and improving cooling performance without reducing the vehicle's economy or riding feel.

[0066] When selecting the cooling means, the selection method may be changed depending on the vehicle driving mode (normal mode, eco mode, sports mode, etc.) selected by the driver.

[0067] As is clear from the above explanation, according to the vehicle cooling device 10 of the present invention, the TCU 30, which is the cooling means control means, accurately estimates the temperature of the coolant used in the belt-type continuously variable transmission 3, which is the power transmission device, based on the heat balance of the belt-type continuously variable transmission 3, which is the power transmission device, acquired by the power transmission device heat balance acquisition means 31, and the cooling heat balance of the cooling means 1 to 5 acquired by the cooling heat balance acquisition means 32, and appropriately controls the cooling means only when the estimated coolant temperature Tp exceeds the upper limit temperature (upper limit value) Tc of the coolant temperature (Tp>Tc), thereby achieving the effect of suppressing the coolant temperature to below the upper limit temperature Tc and improving cooling performance without causing a decrease in the vehicle's economy or riding feel.

[0068] In the above embodiments, cooling means 1 operates the shutter grill 13, cooling means 2 controls the rotation speed of the radiator fan 14, cooling means 3 controls the rotation speed of the engine 1, cooling means 4 changes the gear ratio of the belt-type continuously variable transmission 3, and cooling means 5 reduces the output of the engine 1, but this is not limited to these and other cooling means may be used, and the number of cooling means is also arbitrary.

[0069] Furthermore, in the above embodiment, an example has been described in which the present invention is applied to a vehicle cooling device 10 that cools the coolant (ATF) used in a belt-type continuously variable transmission 3, but the present invention can also be applied to cooling devices that cool fluids used in a torque converter 2 or other power transmission devices.

[0070] Furthermore, the vehicle cooling device of the present invention can be applied not only to vehicles driven by an engine as shown in the above embodiment, but also to hybrid vehicles (HEVs) driven by both an engine and an electric motor. Figure 10 is a diagram showing a schematic configuration of a vehicle cooling device and a power transmission system of a vehicle equipped with the same when the vehicle cooling device of the present invention is applied to a hybrid vehicle. In this figure, components that are the same as or common to those in Figure 1 are given the same reference numerals, and the following description will focus only on the differences from Figure 1.

[0071] 10 includes two radiators for cooling the coolant: a first radiator 11-1 for the engine and a second radiator 11-2 for the electric motor (for HEV). The cooling circuit 17-2 includes a first closed circuit including a water pipe e that guides the coolant, which has been heated after cooling the engine 1, to the first radiator 11-1, and a water pipe f that returns the coolant cooled by the first radiator 11-1 to the engine 1. The second closed circuit includes a water pipe g that guides the coolant, which has been subjected to heat exchange with the coolant circulating in the DU (Drive Unit) 3-2 in the heat exchanger 20, to the electric water pump 18, a water pipe h that guides the coolant discharged from the electric water pump 18 to the inlet of the second radiator 11-2, and a water pipe i that returns the coolant cooled by the second radiator 11-2 and flowing out from the outlet of the second radiator 11-2 to the heat exchanger 20. The second closed circuit also includes a bypass water pipe (bypass pipe) j for supplying cooling water to a PDU (Power Drive Unit) 40, which is a power control device for controlling the power supplied to the electric motor, etc., to cool the PDU 40.

[0072] Furthermore, the present invention is not limited to the application of the above-described embodiments, and various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0073] 1 Engine (prime mover) 3 Belt-type continuously variable transmission (power transmission device, automatic transmission) 10 Vehicle cooling system 11 Radiator 12 Grill 13 Shutter grill (opening / closing part) 14 Radiator fan 15 Electric motor 16 Mechanical water pump 17 Water cooling circuit 18 Electric water pump 19 Water temperature sensor (engine coolant temperature acquisition means) 20 Heat exchanger 21 Liquid cooling circuit 22 Electric fluid pump 23 Liquid temperature sensor (power transmission device coolant temperature acquisition means) 24 Mechanical fluid pump 30 TCU (cooling means control means) 31 Power transmission device heat balance acquisition means 32 Cooling heat balance acquisition method 41 Rotation sensor (motor rotation acquisition means) 43 Vehicle speed sensor (vehicle speed acquisition means) T Coolant temperature Tc Upper limit temperature (upper limit) Tp Estimated coolant temperature (predicted coolant temperature)

Claims

1. a prime mover cooled by cooling water; a power transmission device that is cooled by a coolant and transmits a driving force of the prime mover; a plurality of cooling means for cooling the power transmission device; A vehicle cooling device mounted on a vehicle having a power transmission device heat balance acquisition means for acquiring a heat balance of the power transmission device; a cooling heat balance acquisition means for acquiring a cooling heat balance of the cooling means; a cooling means control means for controlling the cooling means; The cooling means control means A cooling device for a vehicle, characterized in that a cooling means to be used is selected from a plurality of cooling means and controlled based on the heat balance of the power transmission device acquired by the power transmission device heat balance acquisition means and the cooling heat balance of the cooling means acquired by the cooling heat balance acquisition means.

2. The vehicle is a coolant temperature acquisition means for acquiring a coolant temperature of the power transmission device; The cooling means control means 2. The vehicle cooling system according to claim 1, wherein the cooling means is controlled only when a predicted coolant temperature predicted from the coolant temperature and the heat balance exceeds an upper limit of the coolant temperature.

3. The vehicle is Further, a heat exchanger for cooling the cooling liquid is provided. The power transmission device heat balance acquisition means A heat generation amount due to operation of the power transmission device; a surface heat dissipation amount of the power transmission device; and The heat dissipation amount of the heat exchanger; 2. The vehicle cooling device according to claim 1, wherein the heat balance of the power transmission device is obtained based on the heat balance of the power transmission device.

4. The vehicle is a prime mover rotation speed acquisition means for acquiring the rotation speed of the prime mover; a prime mover torque acquisition means for acquiring the torque of the prime mover; a prime mover coolant temperature acquisition means for acquiring a coolant temperature of the prime mover; a vehicle speed acquisition means for acquiring a vehicle speed of the vehicle; a coolant temperature acquisition means for acquiring a coolant temperature of the power transmission device; and The power transmission device heat balance acquisition means the rotation speed of the prime mover acquired by the prime mover rotation speed acquisition means; the torque of the prime mover acquired by the prime mover torque acquisition means; and The coolant temperature acquired by the engine coolant temperature acquisition means; and The vehicle speed acquired by the vehicle speed acquisition means; the coolant temperature acquired by the coolant temperature acquisition means; and 2. The vehicle cooling device according to claim 1, wherein the heat balance of the power transmission device is obtained from at least one of the following information.

5. The vehicle is a prime mover rotation speed acquisition means for acquiring the rotation speed of the prime mover; a prime mover torque acquisition means for acquiring the torque of the prime mover; a prime mover coolant temperature acquisition means for acquiring a coolant temperature of the prime mover; a vehicle speed acquisition means for acquiring a vehicle speed of the vehicle; a coolant temperature acquisition means for acquiring a coolant temperature of the power transmission device; and further comprising at least one of The cooling heat balance acquisition means the rotation speed of the prime mover acquired by the prime mover rotation speed acquisition means; the torque of the prime mover acquired by the prime mover torque acquisition means; and The coolant temperature acquired by the engine coolant temperature acquisition means; and The vehicle speed acquired by the vehicle speed acquisition means; the coolant temperature acquired by the coolant temperature acquisition means; and 2. The vehicle cooling device according to claim 1, wherein the cooling heat balance of the cooling means is obtained from at least one of the following information.

6. The cooling means control means The cooling means to be used is 2. The vehicle cooling system according to claim 1, wherein the cooling heat balance is selected so that the minimum amount of heat exceeds the required amount of heat determined from the heat balance.

7. The cooling means control means The cooling means to be used is 2. The vehicle cooling device according to claim 1, wherein a combination of one or more cooling means is selected such that the cooling heat balance exceeds the required heat amount determined from the heat balance and is minimized.

8. The cooling means each have an evaluation score related to the economy and riding comfort of the vehicle, The cooling means control means The cooling means to be used is 2. The vehicle cooling device according to claim 1, wherein the cooling heat balance exceeds the required heat amount calculated from the heat balance and the combination of one or more cooling means with the smallest evaluation score is selected.

9. The cooling means control means calculating the evaluation score of each of the cooling means from information obtained from a vehicle running state; The cooling means to be used is 2. The vehicle cooling device according to claim 1, wherein the cooling heat balance exceeds the required heat amount calculated from the heat balance and the combination of one or more cooling means with the smallest evaluation score is selected.

10. The cooling means control means The cooling means to be used is 2. The vehicle cooling device according to claim 1, wherein the selection method is changed based on a driving mode selected by a driver.

11. The vehicle is an opening / closing section for controlling wind from outside the vehicle that is introduced around the vehicle drive device while the vehicle is running; The first cooling means, which is one of the cooling means, 2. The vehicle cooling device according to claim 1, wherein the opening and closing portion is operated.

12. The vehicle is a water cooling circuit in which the cooling water circulates through the motor and a radiator; a liquid cooling circuit through which the cooling liquid circulates; a radiator fan that cools the cooling water flowing through the radiator and circulates the atmosphere around the power transmission device; and The second cooling means, which is one of the cooling means, 2. The vehicle cooling device according to claim 1, wherein the rotation speed of the radiator fan is controlled.

13. The vehicle is a water cooling circuit in which the cooling water circulates through the motor and a radiator; a cooler that cools the cooling liquid by heat exchange with the cooling water flowing through the water-cooling circuit; a liquid cooling circuit through which the cooling liquid circulates; and the prime mover controls the flow rate of the water cooling circuit by its rotation; The third cooling means, which is one of the cooling means, 2. The vehicle cooling device according to claim 1, wherein the rotational speed of the engine is controlled.

14. the power transmission means is an automatic transmission, The fourth cooling means, which is one of the cooling means, 2. The vehicle cooling system according to claim 1, wherein the gear ratio of the automatic transmission is changed in a direction that improves the efficiency of the automatic transmission so that the output of the engine and the vehicle speed are constant.

15. The fifth cooling means, which is one of the cooling means, 2. The cooling device for a vehicle according to claim 1, wherein the output of the engine is reduced.

16. The prime mover is 2. The cooling device for a vehicle according to claim 1, wherein the cooling device is an engine.

17. The power transmission device is 2. The cooling device for a vehicle according to claim 1, wherein the cooling device is a belt-type continuously variable transmission.

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