JP2003269168A - Method of operating engine cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of operating an engine cooling device for solving a problem of the engine cooling device with separate pumps for cooling a cylinder block and a cylinder head that a large energy loss may be caused as the pump for cooling the cylinder block is operated on the condition with a low energy efficiency. <P>SOLUTION: In handling the increase of requests for cooling the cylinder block, the output of the pump for cooling the cylinder head is increased while the pump for cooling the cylinder block is stopped to cool down the cylinder head more intensively, and the cooling performance on the cylinder block is improved via the heat conduction between the cylinder block and the cylinder head. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine (internal combustion engine) cooling device, and more particularly to a method of operating the same.

[0002]

2. Description of the Related Art An engine housing is usually composed of a combination of a cylinder block and a cylinder head. When the cooling system is a liquid cooling system, a cooling liquid flow passage formed in each of the cylinder block and the cylinder head. The (water jacket) is communicated with the joint between the cylinder block and the cylinder head, and the cooling liquid is circulated by a single pump through these cooling liquid flow paths. In this case, in general, in order to easily and reliably bleed the cooling fluid passage, the cooling fluid first flows through the cooling fluid passage in the engine from the bottom to the top, so that the cylinder normally occupies the lower portion of the engine. It is passed through the coolant flow passage of the block and then through the coolant passage of the cylinder head which occupies the upper part of the engine. However, while the cylinder head receives a large amount of heat due to the detonation of the fuel and requires strong cooling, the cylinder block is maintained at an appropriately high temperature in order to reduce the frictional resistance of the piston on the cylinder wall. If the problem of air bleeding is solved, the cooling liquid is preferably passed through the cooling passage of the cylinder head first, and then to the cooling passage of the cylinder block, since gentle cooling is preferable. It is rational to pass, and there are also this form.

Further, the cooling liquid sent by one pump is divided by a valve into a cooling liquid flow flowing through the cooling liquid flow path of the cylinder block and a cooling liquid flow flowing through the cooling liquid flow path of the cylinder head, whereby the cylinder block It is also known to individually control the cooling degree for the cylinder head and the cooling degree for the cylinder head as shown in Japanese Patent Laid-Open No. 5-86970. Furthermore, by forming a cooling liquid circulation circuit by a pump and a radiator for the cooling liquid flow passage of the cylinder block and the cooling liquid flow passage of the cylinder head, and individually controlling the operation of each cooling liquid circulation circuit. It is also known to control the temperatures of the cylinder block and the cylinder head to different desired temperatures, as disclosed in Japanese Patent Laid-Open No. 63-88215.

[0004]

With regard to a pump used in an engine cooling system, the relationship between the fluid flow rate of the fluid and the energy consumed by the pump to achieve the fluid flow rate is that the former is the pump flow rate and the latter is the latter. Is expressed as pump power consumption, the characteristics shown in FIG. 1 are exhibited, and at a place where the pump flow rate is small, the energy efficiency for sending the fluid gradually decreases as the flow rate approaches zero.
On the other hand, as described above, when comparing the cooling degrees required for the cylinder block and the cylinder head, the cooling degree required for the cylinder block is generally much lower than that required for the cylinder head, although it depends on the operating state of the engine. If separate pumps are provided for cooling the cylinder block and for cooling the cylinder head, this is because the pump for cooling the cylinder block may remain stopped when the engine load is low. Even when the engine load increases and the pump has to be operated, there are still some engine operating conditions where the pump flow rate may be quite small. The pump will operate with low energy efficiency. Moreover, such a low load engine operation may take a long time, in which case the cylinder block cooling pump will continue to operate with low energy efficiency.

According to the present invention, when separate pumps are provided for cooling the cylinder block and the cylinder head, the cylinder block cooling pump is operated in a low energy efficiency state as described above. Focusing on the problem that a large energy loss may occur, it is an object to provide an operating method of an engine cooling device that overcomes such a problem.

[0006]

In order to solve the above-mentioned problems, the present invention provides a first cooling liquid passage for cooling a cylinder block, a second cooling liquid passage for cooling a cylinder head, and A radiator, a first pump for passing a cooling liquid through the first cooling liquid passage, a second pump for passing a cooling liquid through the second cooling liquid passage, and the first pump Of the cooling liquid flow path, the second cooling liquid flow path, the radiator, the first pump and the second pump, and a pipeline network that connects them to each other, and a distribution channel of the pipeline network selectively. A circuit for circulating the coolant through the cylinder block and the radiator by switching the first pump and a circuit for circulating the coolant through the cylinder head and the radiator by the second pump are selectively used. And a switching valve to be formed. In the method of operating the gin cooling device,
In response to a cooling request of the cylinder block, the first pump is stopped within a range that can be responded to by the operation of the second pump while the first pump is stopped, and the first pump is stopped according to the temperature rise of the cylinder block. An engine cooling device operating method characterized by increasing the output of a second pump.

When the operating mode in which only the second pump is operated while the first pump is stopped is switched to the operating mode in which both the first and second pumps are operated, the temperature of the cylinder block is set to a predetermined value. May be performed when the threshold of is exceeded.

Alternatively, in the operating method of the engine cooling device as described above, both the first and second pumps can be operated according to the operation mode in which the first pump is stopped and only the second pump is operated. The switching to the operation mode in which the pump is operated is increased to such an extent that when the cooling request of the cylinder block starts the first pump, the pump is operated in an operation region in which the pump flow rate is substantially proportional to the pump power consumption. It may be timed.

In the engine cooling device operating method as described above, the output increase of the second pump according to the temperature increase of the cylinder block may be performed in a normal continuous correspondence relationship. It may be performed stepwise every time the temperature of the cylinder block exceeds a predetermined threshold value.

[0010]

With respect to the cooling of the engine, since the housing of the engine is divided into the cylinder block and the cylinder head, and the cooling liquid passages are provided in each of them, the cooling of the cylinder block is performed by the cylinder. The idea is fixed that it is performed only by the cooling liquid flowing through the cooling liquid flow path of the block, and the cylinder head is cooled only by the cooling liquid flowing through the cooling liquid flow path of the cylinder head. However, it is possible to transfer heat by considerably large heat conduction between the cylinder block and the cylinder head, which are made of good heat conductors that are closely adhered to each other at the joint surface.

Therefore, when separate pumps are provided for cooling the cylinder block and the cylinder head, the cylinder block cooling pump may remain stopped. When the cylinder block has increased, and the circulation of the cooling liquid is desired, the output of the cylinder head cooling pump is increased and the cylinder head is cooled more strongly without immediately starting the cylinder block cooling pump. By increasing the amount of heat transferred from the cylinder block to the cylinder head by heat conduction, the demand for cooling the cylinder block is further increased, and the cylinder block cooling pump can be operated with a considerable output from the beginning. You can delay its start until the cylinder block It is possible to avoid that the cooling pump is operated in a low energy efficiency and low-load operation range.

Even if the temperature of the cylinder block rises as described above, in order to increase the cooling effect on the cylinder block by increasing the output of the cylinder head cooling pump, it is controlled how much the cylinder block cooling pump operation is suppressed. It becomes an upper problem. The degree of cooling required by the cylinder block or cylinder head differs depending on the engine operating conditions such as engine load, but the function that the cooling device should fulfill is to ultimately protect the cylinder block or cylinder head from overheating. Therefore, switching from the operating mode in which the cylinder block cooling pump is stopped and only the cylinder head cooling pump is operated to the operating mode in which both the cylinder block cooling pump and the cylinder head cooling pump are operated is performed by changing the cylinder block temperature. On the basis of the above, it is significant as one control method to be taken when it exceeds a predetermined threshold value.

Alternatively, the present invention intends to delay the start of the cylinder block cooling pump in order to prevent the pump from operating in the low pump flow rate region where the energy efficiency is low, and Switching from the operation mode in which the block cooling pump is stopped and only the cylinder head cooling pump is operated to the operation mode in which both the cylinder block cooling pump and the cylinder head cooling pump are operated starts the cylinder block cooling pump. One of the other reasons is that the demand for cooling of the cylinder block increases from the beginning of startup to such an extent that the pump flow rate is operated substantially in proportion to the pump power consumption. This is a meaningful control method.

When the output of the cylinder head cooling pump is increased in response to the temperature rise of the cylinder block while the cylinder block cooling pump is stopped,
Although the output increase of the cylinder head cooling pump may be controlled continuously (that is, steplessly) by a normal corresponding control, the output control of the cylinder head cooling pump according to the temperature increase of the cylinder block according to the present invention is Even when the output of the cylinder head cooling pump is increased stepwise each time the temperature of the cylinder block exceeds a predetermined threshold value, the effect can be sufficiently exhibited. In this way, by controlling the output control of the cylinder head cooling pump according to the temperature of the cylinder block by switching between different outputs prepared in several stages, the control structure may be simplified in some cases. Is possible.

[0015]

FIG. 2 is a schematic diagram showing an engine for carrying out an engine cooling device operating method according to the present invention together with its cooling device. In the figure, 1 is a cylinder block, 2 is a cylinder head, and they are combined so that their joint surfaces have as high thermal conductivity as possible. Although a gasket is usually provided on the joint surface between the cylinder block and the cylinder head, in order to apply the present invention in particular, the gasket is made of a material and / or structure having as high thermal conductivity as possible. It is preferable that at least a part of both joint surfaces is a labyrinth-shaped contact surface, and other means for increasing the thermal conductivity between them may be incorporated.

Reference numeral 3 is a radiator. Each of the cylinder block and the cylinder head is provided with a cooling liquid flow passage that allows the cooling liquid to flow therethrough, and the cooling liquid is sent to the cooling liquid flow passage of the cylinder block by the operation of the pump 4. The cooling liquid is fed into the cooling liquid flow path of the cylinder head by the operation of the pump 5. The cooling liquid flowing out of the cooling liquid flow path of the cylinder block flows through the return pipe 7 and returns to the suction port of the pump 4 or flows through the radiator and returns to the suction port of the pump 4 depending on the switching state of the three-way valve 6. . Similarly, the cooling liquid flowing out of the cooling channel of the cylinder head either flows through the radiator and returns to the suction port of the pump 5 or flows through the return pipe 9 to suck the pump 5 depending on the switching state of the three-way valve 8. Return to mouth. Reference numerals 10, 11, and 12 are temperature sensors for detecting the temperatures of the cylinder block, the cylinder head, and the radiator, respectively.

FIG. 3 shows changes in the engine output, the cylinder head side pump flow rate, the cylinder block temperature, and the cylinder block side pump flow rate in a mode in which two embodiments are incorporated in the method for operating the engine cooling device according to the present invention. It is a graph shown as a contrast.

Now, the engine is operating at a very low output W _{1 such as} idling, the cylinder block side pump is not operating, and the cylinder block temperature is T ₁
It is assumed that the engine output has increased from W ₁ at time t ₁ as shown in the figure, starting from the state in which the cylinder head side pump is operating at the pump flow rate Q ₁ .

Due to the increase of the engine output, the temperature of the cylinder block starts to rise gradually from T ₁ at this point,
The flow rate of the cylinder head side pump is increased from Q _{1 as the} cylinder block temperature rises. At this time, as a general example, the pump flow rate on the cylinder head side is continuously (steplessly) increased as the cylinder block temperature rises. This state is indicated by a solid line in the column of cylinder head side pump flow rate, and correspondingly, the cylinder block temperature changes as indicated by a solid line in the column. However, as a different embodiment, the cylinder block temperature T ₁ is just one threshold value for the stepwise switching control of the cylinder head side pump flow rate, and the cylinder block temperature is the threshold value T 1. By exceeding ₁ , the pump flow rate on the cylinder head side is increased stepwise from Q ₁ to Q ₂ . This state is indicated by a broken line in the column of cylinder head side pump flow rate, and the cylinder block temperature correspondingly changes as indicated by a broken line in the column.

When the cylinder block temperature exceeds one threshold value and the cylinder head side pump flow rate increases stepwise, after the cylinder block temperature exceeds the threshold value, it increases stepwise. Due to the cooling of the cylinder block via heat conduction due to the generated flow rate, the cylinder block temperature may drop below the temporary threshold value as shown by the broken line in the figure. However, by incorporating a hysteresis in the switching control of the cylinder head side pump flow rate based on the cylinder block temperature, it is possible to prevent the control from becoming unstable.

In any case, by increasing the cylinder head side pump flow rate with respect to the rise of the cylinder block temperature in the above manner, the cylinder block is subjected to the increased cooling action from the cylinder head by heat conduction. However, the cylinder block temperature still reaches T ₂ at time t ₂ depending on the situation where the engine output is increased as shown. In the case of the embodiment shown by the solid line, there is no particular change in the control mode here, and when the cylinder block temperature continues to rise further than this, the cylinder head side pump flow rate is controlled to gradually increase correspondingly. However, in the case of the above-described broken line embodiment, T
₂ is the next threshold value for the stepwise control of the cylinder head side pump flow rate based on the cylinder block temperature. When the cylinder block temperature exceeds T ₂ , the cylinder head side pump flow rate changes from Q ₂ to Q ₃ . It is increased stepwise.

When the cylinder block temperature continues to rise further than this, in the embodiment indicated by the solid line, the pump flow rate on the cylinder head side is controlled to gradually increase, and in the embodiment indicated by the broken line, the time point is increased. at t ₃ the cylinder block temperature by exceeding the following thresholds T _3, the cylinder head side pump flow rate is increased stepwise to Q ₄ from Q _3.

Thus, at time t _{5, the} cylinder block temperature reaches Ts. At this time, in the embodiment indicated by the broken line, the cylinder block temperature may reach Ts slightly later than the time point t ₅ . In any case, the cylinder block temperature Ts is a threshold temperature determined to start the cylinder block cooling pump when the cylinder block temperature rises any more. Therefore, at this point, the operation of the cylinder block cooling pump was started,
The cylinder block side pump flow rate rises from this as shown. In this case, the pump flow rate on the cylinder block side is set to a value exceeding the broken line region in FIG. 1 from the beginning of the pump operation. The flow rate of the cylinder head side pump may be lowered as shown in the figure corresponding to the start of operation of the cylinder block side pump. Due to the start of the operation of the cylinder block cooling pump and the decrease in the cylinder head side pump flow rate, the cylinder block temperature decreases as shown in the figure and then stabilizes.

On the other hand, the operation mode in which both the cylinder block cooling pump and the cylinder head cooling pump are operated is switched from the operation mode in which the cylinder block cooling pump is stopped and only the cylinder head cooling pump is operated. Even if the block cooling pump is started because the cylinder block temperature rises from the beginning until it can be operated in the region where the broken line part in FIG. The demand gradually increases as shown by the chain double-dashed line in FIG. 3, and the cylinder block side pump is not operated until Q ₀ is reached, and at time t ₄ , the demand for the cylinder block side pump flow rate becomes Q. The operation of the cylinder block side pump may be started when it reaches ₀ .
Even in such a control mode, by appropriately setting the correspondence between the values of Ts and Q ₀ , it is possible to make the time point t ₄ almost coincide with the time point t ₅ .

In this way, the cylinder block cooling pump provided for cooling the cylinder block, which originally has a cooling demand that starts from zero and continuously increases by the operation of the engine, is operated during the operation of the engine. If it is stopped, or if it is operated, it operates only in the output region above a certain height, which is out of the operating region with poor energy efficiency shown by the broken line in FIG. Can be controlled steplessly to any value within a predetermined control range.

Although the present invention has been described in detail above with reference to some embodiments, it will be apparent to those skilled in the art that various modifications can be made to these embodiments within the scope of the present invention. Let's do it.

[Brief description of drawings]

FIG. 1 is a graph showing a general characteristic of the magnitude of pump power consumption with respect to the pump flow rate of a pump used in an engine cooling device.

FIG. 2 is a schematic view showing an engine for carrying out an engine cooling device operating method according to the present invention together with its cooling device.

FIG. 3 shows an embodiment of a method for operating an engine cooling device according to the present invention, in which engine output, cylinder head side pump flow rate,
The graph shown as a comparison of the change of the cylinder block temperature and the cylinder block side pump flow rate.

[Explanation of symbols]

1 ... Cylinder block 2 ... Cylinder head 3 ... radiator 4. Cylinder block cooling pump 5 ... Cylinder head cooling pump 6 ... Three-way valve 7 ... Return pipe 8 ... Three-way valve 9 ... Return pipe 10, 11, 12 ... Temperature sensor

Claims (4)

[Claims] 1. A first cooling liquid flow path for cooling a cylinder block, a second cooling liquid flow path for cooling a cylinder head, a radiator, and a cooling liquid flow through the first cooling liquid flow path. A first pump for flowing through, a second pump for flowing a cooling liquid through the second cooling liquid passage, the first cooling liquid passage, the second cooling liquid passage, and the radiator. And a pipe network that connects the first pump and the second pump to each other, and a flow path of the pipe network is selectively switched so that the cylinder block and the radiator pass by the operation of the first pump. And a switching valve that selectively forms a circuit that circulates the cooling liquid and a circuit that circulates the cooling liquid through the cylinder head and the radiator by the second pump. Cylinder block cooling required In contrast, with the first pump stopped, the first pump is stopped within a range that can be controlled by the operation of the second pump, and the output of the second pump is increased according to the temperature rise of the cylinder block. A method for operating an engine cooling device, the method comprising: 2. The temperature of the cylinder block is switched from the operation mode in which the first pump is stopped and only the second pump is operated to the operation mode in which both the first and second pumps are operated. The engine cooling device operating method according to claim 1, wherein the engine cooling device operating method is performed when the temperature exceeds a predetermined threshold value. 3. A cylinder block is cooled by switching from an operation mode in which the first pump is stopped and only the second pump is operated to an operation mode in which both the first and second pumps are operated. 2. The request according to claim 1, wherein the request is such that when the first pump is started, the pump is increased to such an extent that the pump is operated in an operation region in which the pump flow rate is substantially proportional to the power consumption of the pump. Engine cooling system operating method. 4. The output increase of the second pump according to the temperature rise of the cylinder block is performed stepwise every time the temperature of the cylinder block exceeds a predetermined threshold value. 4. The method for operating an engine cooling device according to any one of 3 to 3.