JP2010163920A - Cooling device of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To complete warming-up as the whole engine early by promoting temperature rise of a cylinder head by appropriate cooling of the cylinder head during warming-up of the engine. <P>SOLUTION: As a water jacket within the engine, a head-side jacket part Jh and a block-side jacket part Jb are formed respectively on a cylinder head 1 and a cylinder block 2. During warming-up of the engine, flow of cooling water in the block-side jacket part Jb is interrupted to stay cooling water within the cylinder block 2, while cooling water is circulated through the head-side jacket part Jh. While the flow of cooling water in the block-side jacket part Jb is interrupted, the flow rate (head internal flow rate) Qwh of cooling water flowing in the head-side jacket part Jh is limited. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an engine cooling device, and more specifically, by stagnation of cooling water in a cylinder block during engine warm-up, the temperature rise of the inner wall of the cylinder bore is promoted, and deterioration of fuel consumption due to friction loss is suppressed. To improve technology.

There are the following technologies aimed at realizing further reduction in fuel consumption of an engine from the viewpoint of reducing friction loss after the engine is started at a low temperature. Cylinder bore inner wall by stopping the circulation of the cooling water through the water jacket (cylinder block side water jacket) formed in the cylinder block during the warm-up of the engine after the cold start, and stopping the cooling water in the cylinder block The temperature rise is increased to optimize the viscosity of the lubricating oil at an early stage after starting, thereby reducing the friction loss. Specifically, inside the engine, the water jacket on the cylinder head side and the water jacket on the cylinder block side are formed in parallel, and while the engine is warming up, the coolant is bypassed by bypassing the radiator by regulating the thermostat valve, The inflow of the cooling water to the cylinder block side water jacket is blocked, and the cooling water is circulated only through the cylinder head side water jacket. On the other hand, after the warm-up is completed, the cooling water flows through the radiator by the flow switching operation of the thermostat valve, and the cooling water is circulated through both the cylinder head side water jacket and the cylinder block side water jacket. (Patent Document 1).
JP-A-2004-278489 (paragraph numbers 0015 to 0017)

  However, in the above technique, while the circulation of the cooling water through the cylinder block side water jacket is interrupted, there is no restriction on the circulation through the other cylinder head side water jacket. Here, if the circulation of the cooling water through the cylinder block side water jacket is simply interrupted in accordance with the above technique during the warming up of the engine, all the cooling water sent out by the circulation pump is transferred to the cylinder head side water jacket. Introduced, during the warm-up, more cooling water than the amount necessary to ensure the cooling performance required for the cylinder head will circulate through the cylinder head side water jacket. As a result, the cylinder head is cooled more than necessary, the temperature rise of the cylinder head is suppressed, and it takes a relatively long time to complete the warm-up of the entire engine. It will increase. When the fuel temperature increase correction is continued with respect to the delay in warm-up, the fuel consumption reduction effect is reduced by reducing the friction loss because of the increased fuel amount.

  The present invention provides an engine cooling device that takes the above problems into consideration, and by appropriately cooling the cylinder head during engine warm-up, the temperature rise of the cylinder head is promoted to warm up the engine as a whole. The purpose is to reduce the unburned gas emission and further reduce the fuel consumption of the engine.

  The engine cooling device according to the present invention includes a head side jacket portion formed in a cylinder head and a block side jacket portion formed in a cylinder block as a water jacket inside the engine, and during warming up of the engine The flow of the cooling water in the block side jacket portion is blocked to stagnate the cooling water in the cylinder block, while the cooling water is circulated through the head side jacket portion. Here, in the present invention, when the flow of the cooling water in the block side jacket portion is interrupted, the flow rate of the cooling water flowing through the head side jacket portion is limited. Specifically, the flow rate of the cooling water when the flow in the block side jacket portion is interrupted is reduced below the amount that is normally allocated for cooling the cylinder head after the engine warm-up is completed, or As the temperature of the cylinder head increases, the temperature is decreased when the temperature is lower than when the temperature is high.

  According to the present invention, during the warm-up of the engine, the flow of the cooling water in the block-side jacket portion is interrupted, whereby the temperature rise of the cylinder bore inner wall can be promoted and the fuel consumption can be reduced by reducing the friction loss. Here, according to the present invention, during the warm-up, the temperature of the combustion chamber wall is increased early by promoting the temperature rise of the cylinder head by restricting the flow rate of the cooling water flowing particularly through the head side jacket portion. At the same time, warm-up of the engine as a whole can be completed at an early stage, so that the emission of unburned gas can be suppressed and the fuel consumption of the engine can be further reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 schematically shows the configuration of an engine cooling device according to an embodiment of the present invention.

  In the present embodiment, a vehicle engine is targeted, and a head-side jacket portion Jh is formed in the cylinder head 1 and a block-side jacket portion Jb is formed in the cylinder block 2 as a water jacket inside the engine. These jacket portions Jh, Jb are provided in parallel with each other inside the engine, and have independent openings i1, i2 and e1, e2 on the side surfaces of the cylinder head 1 or the cylinder block 2, respectively. Specifically, the head side jacket portion Jh opens at an inlet portion i1 provided on one (here, the front side) side surface of the cylinder head 1 and is provided on the other (rear side) side surface. Opened at the outlet e1. On the other hand, the block-side jacket portion Jb opens at an inlet portion i2 provided on the front side surface of the cylinder block 2, and opens at an outlet portion e2 provided on the rear side surface. A cooling water distribution pipe 3 is connected to the upstream side of the water jacket, and the cooling water flowing through the collecting section of the distribution pipe 3 extends to the front side surface of the cylinder head 1 and the cylinder block 2. Are supplied to the inlet portions i1 and i2 and introduced into the head side jacket portion Jh and the block side jacket portion Jb. The cooling water flowing out from the outlets e1 and e2 through the jackets Jh and Jb merges in the collecting pipe 4 connected to the side surface on the rear side of the cylinder head 1 and the cylinder block 2 and bypasses the radiator 5. It is again introduced into the water jacket inside the engine via the connected return pipe 6 and distribution pipe 3. Here, the radiator 5 is connected between the collecting pipe 4 downstream of the water jacket and the distribution pipe 3 upstream of the water jacket. A thermostat valve 7 is installed on the downstream side of the radiator 5, and cooling water reintroduced into the water jacket between the return pipe 6 and the radiator 5 by the operation of the thermostat valve 7 according to the progress of engine warm-up. The passage is switched. While the engine is warming up, the circulation pump 8 circulates the cooling water through the water jacket and the return pipe 6 (in other words, bypasses the radiator 5), while at the normal time after the warming up, Cooling water is circulated through the jacket and the radiator 5.

  In the present embodiment, in the collecting pipe 4 downstream of the water jacket, a block side shut-off valve 9a is installed at the junction, and a flow control valve 10 is installed upstream of the distribution pipe 3 upstream of the water jacket. The block side shut-off valve 9a always allows the head side jacket portion Jh and the passage downstream of the collecting pipe 4 to communicate with each other to allow the flow of cooling water in the head side jacket portion Jh, while the block side jacket portion Jb and the collecting pipe 4 downstream. The connection with the passage is selectively cut off. In the present embodiment, during the warm-up of the engine after the cold start, the block side shutoff valve 9a shuts off the flow of the cooling water in the block side jacket portion Jb to promote the temperature rise of the cylinder bore inner wall, and the flow control valve The flow rate of the cooling water flowing through the head side jacket portion Jh is limited by 10 to suppress the cooling of the cylinder head 1 during the warm-up to a necessary limit. The operations of the block side shut-off valve 9a and the flow rate control valve 10 are controlled based on the in-head water temperature Twh detected by the water temperature sensor 21 by the control unit 11 configured as an electronic control unit. The water temperature sensor 21 is installed so as to be able to detect the temperature Twh of the coolant formed in the vicinity of the exhaust port located on the most downstream side with respect to the coolant flow in the cylinder head 1 in the head side jacket portion Jh. . Here, the block-side shutoff valve 9a and the control unit 11 constitute a “flow path switching device”, and the flow rate control valve 10 and the control unit 11 constitute a “flow rate limiting device”.

  Next, the operation of the engine cooling device according to this embodiment will be described.

  2 and 3 are flowcharts showing the flow of cooling control during engine warm-up. FIG. 1 shows the first half of this control, and FIG. 3 shows the second half.

  When the driver turns on the power by operating the key switch, the control unit 11 activates the circulation pump 8 in S101.

  In S <b> 102, the block-side shut-off valve 9 a is closed to shut off the flow of cooling water in the block-side jacket portion Jb, and the cooling water is stagnated in the cylinder block 2. Thereby, the temperature rise of the cylinder block 2 during warm-up is promoted.

  In S103, the opening area of the flow rate control valve 10 is decreased so that the flow rate Qwh of the cooling water flowing through the head side jacket portion Jh is smaller than the amount allocated for cooling the cylinder head 1 at the normal time after the warm-up is completed. Restrict. Thereby, cooling of the cylinder head 1 during warming-up is suppressed to a necessary limit. In the present embodiment, the head-side jacket portion Jh and the block-side jacket portion Jb are formed in parallel, and the flow rates flowing through the jacket portions Jh and Jb can be set individually. The amount allocated for cooling is 40 liters and is reduced to 10 liters.

  In S104, the temperature (water temperature in the head) Twh of the cooling water flowing through the head side jacket portion Jh is detected. In the present embodiment, the coolant temperature sensor 21 detects the local coolant temperature Twh around the exhaust port located on the most downstream side with respect to the coolant flow in the cylinder head 1.

  In S105, it is determined whether or not the water temperature detection value Twh of the water temperature sensor 21 has reached a predetermined temperature T1. If reached, the process proceeds to S106. If not, the process returns to S104, and the processes of S104 and S105 are repeated until the output value Twh of the water temperature sensor 21 reaches T1. The predetermined temperature T1 is set to a temperature for determining that the cylinder head 1 has warmed up and escaped from the low temperature range where discharge of unburned gas becomes a problem.

  In S106, the flow rate control valve 10 is controlled to be fully opened, and the flow rate restriction regarding the cooling water flowing through the head side jacket portion Jh is released.

  In S107, the block side shut-off valve 9a is opened to start the circulation of the cooling water through both the head side jacket portion Jh and the block side jacket portion Jb.

  After starting the circulation of the cooling water through the block-side jacket portion Jb, the water temperature sensor 21 detects the in-head water temperature Twh in S201 of FIG.

  In S202, it is determined whether or not the water temperature detection value Twh of the water temperature sensor 21 has reached a predetermined temperature T2. If reached, the process proceeds to S203. If not, the process returns to S201, and the processes of S201 and 202 are repeated until the output value Twh of the water temperature sensor reaches T2. By detecting that the water temperature Twh in the head once lowered due to the mixing of the cooling water stagnating in the block side jacket portion Jb rises again and reaches the predetermined temperature T2, the cylinder block 2 escapes from the low temperature range. It is determined. Here, the thermostat valve 7 is set so that its position is switched when the water temperature Twh in the head (the temperature of the cooling water in the entire cooling system excluding the radiator 5) reaches a predetermined temperature T2. By switching the position of the valve 7, the inflow of cooling water from the radiator 5 is started.

  In S203, the opening area of the flow control valve 10 is decreased. By limiting the flow rate of the cooling water circulating in the entire cooling system, the flow of the low-temperature cooling water flowing from the radiator 5 is reduced by the operation of the thermostat valve 7, and the decrease in the water temperature due to the mixing of the low-temperature water is suppressed. is there.

  In S204, 1 is added to the counter, and the time elapsed after the switching of the thermostat valve 7 is measured.

  In S205, it is determined whether or not the counter value CNT after the addition has reached a predetermined value N1. If reached, the process proceeds to S206. If not, the process returns to S204, and the processes of S204 and S205 are repeated until the counter value CNT reaches N1.

  In S206, assuming that the engine has been warmed up, the flow control valve 10 is fully opened, and the routine proceeds to normal cooling control.

  FIG. 4 shows changes in the in-head water temperature Twh and the cooling water in-head flow rate Qwh during engine warm-up. With reference to the figure, the effect obtained by this embodiment is demonstrated.

  In the present embodiment, while the engine is warming up, the block side shutoff valve 9a blocks the flow of the cooling water in the block side jacket portion Jb, thereby promoting the temperature rise of the cylinder bore inner wall and reducing the friction loss. Can be reduced. Here, in the present embodiment, during the warm-up, the opening area of the flow control valve 10 is reduced, and the flow rate of the cooling water flowing through the head side jacket portion Jh is limited, so that the cooling of the cylinder head 1 is a necessary limit. Thus, the temperature of the combustion chamber wall can be raised early, and warm-up of the entire engine can be completed early. As a result, the emission of unburned gas can be suppressed and the fuel consumption of the engine can be further reduced.

  As shown in FIG. 4, in the present embodiment, the flow rate of the cooling water flowing through the head side jacket portion Jh is set constant during the warm-up of the engine. Then, the flow rate of the cooling water may be increased. As an example, FIG. 5 shows a case where the flow rate of cooling water that is normally allocated for cooling the cylinder head 1 is Q1, and gradually increases from Q0 to Q1, which is smaller than Q1, with respect to the rise in the head water temperature Twh. The flow rate Qwh is set. Thereby, the cooling performance of the cylinder head 1 during warm-up can be made more appropriate, and the temperature rise of the cylinder head 1 can be further promoted. By detecting the temperature Twh of the cooling water in the vicinity of the exhaust port located on the most downstream side with respect to the flow of the cooling water in the cylinder head 1 by the water temperature sensor 21, the in-head water temperature Twh of the jacket portion that tends to be relatively high. Based on the above, the flow rate Qwh in the head can be controlled, and excessive temperature rise of the cylinder head 1 can be suppressed. The increase in the in-head flow rate Qwh is not limited to the in-head water temperature Twh, but may be performed according to the passage of time after starting. In this case, it may be determined that the temperature rise of the cylinder head 1 has been completed when the gradually increasing in-head flow rate Qwh reaches a predetermined flow rate, and circulation of the cooling water through the cylinder block 2 may be started.

  Further, in the present embodiment, after the in-head water temperature Twh reaches the predetermined temperature T2, the flow rate of the cooling water flowing from the radiator 5 to the cooling system is limited over a predetermined period, so that it flows from the radiator 5. A sudden drop in the water temperature due to the mixing of the low-temperature water can be avoided, leakage of the cooling water due to shrinkage of the cooling water seal portion can be prevented, and thermal fatigue of the sealing member can be suppressed. In addition, the inflow limitation of the cooling water from the radiator 5 is not limited to the uniform limitation by time, but the temperature of the cooling water (for example, the water temperature Twh in the head) may be detected and increased or decreased according to the change. Good. Here, the thermostat valve 7 corresponds to a “shut-off valve”, and the flow control valve 10 also functions as a “flow control valve”.

  The case where the head side jacket portion Jh and the block side jacket portion Jb are formed in parallel inside the engine has been described above. However, the present invention is not limited to this, and cooling in which these jacket portions Jh and Jb are formed in series is described. It is also possible to apply to an apparatus. FIG. 6 shows, as an example, a configuration when the present invention is applied to a head pre-cooling type cooling device. While the engine is warming up, the three-way valve 9b blocks the flow of the cooling water in the block side jacket portion Jb and circulates the cooling water only through the head side jacket portion Jh. By restricting the flow rate of the cooling water flowing through the portion Jh, the temperature rise of the cylinder head 1 is promoted during warm-up, and the early completion of warm-up as the whole engine is achieved. The flow rate in the head is limited by restricting the flow path by the flow rate control valve 10, and the flow rate of cooling water allocated for cooling the cylinder head 1 after the engine warm-up is completed (for example, 40 liters corresponding to the total flow rate of 90 liters). ) By reducing the amount to less. After the head internal water temperature Twh reaches the predetermined temperature T1 and it is determined that the cylinder head 1 has escaped from the low temperature region, the flow path of the cooling water is switched by the operation of the three-way valve 9b, and the head side jacket portion Jh is switched to the block side jacket. Cooling water is circulated through the part Jb.

  In the above description, the flow rate of the cooling water is limited by the flow rate control valve 10, but the circulation pump 31 (FIG. 6) having a variable discharge amount is installed on the upstream side of the water jacket, and this is controlled by the control unit 11. It is possible to similarly limit by controlling the discharge amount of the pump 31. Here, the discharge amount variable circulation pump 31 and the control unit 11 constitute a “flow rate limiting device”. As the circulation pump 31, an electric water pump or a mechanical discharge variable pump having a clutch can be adopted.

  It should be noted that when the temperature rise of the cylinder block 2 is completed before the cylinder head 1, the cooling water circulation through the cylinder block 2 may be started without waiting for the temperature rise of the cylinder head 1. It is. A water temperature sensor is provided so that the temperature Twb of the cooling water in the jacket portion Jb in the block can be detected, and circulation through the cylinder block 2 is started when the detected water temperature value Twb of the sensor reaches a predetermined temperature T1. In this case, when the temperature rise of the cylinder head 1 is completed following the cylinder block 2 and the temperature of the cooling water in the entire cooling system excluding the radiator 5 rises, the thermostat valve 7 opens and the radiator 5 The inflow of cooling water will be started.

Schematic which shows the structure of the cooling device of the engine which concerns on one Embodiment of this invention. The flowchart which shows the flow of the cooling control (first half part) which concerns on embodiment same as the above. The flowchart which shows the flow of the cooling control (second half part) which concerns on embodiment same as the above. Time chart of cooling control according to the embodiment Setting table for adjusting the flow rate in the head for cooling control Schematic showing the configuration when the present invention is applied to a head pre-cooling type cooling device

  DESCRIPTION OF SYMBOLS 1 ... Cylinder head, 2 ... Cylinder block, 3 ... Distribution pipe, 4 ... Collecting pipe, 5 ... Radiator, 7 ... Thermostat valve, 8 ... Circulation pump, 9a ... Block side shutoff valve, 10 ... Flow control valve, 11 ... Control Unit, 21 ... water temperature sensor, Jh ... head side jacket portion, Jb ... block side jacket portion.

Claims (9)

As a water jacket inside the engine, it has a head side jacket part formed in the cylinder head and a block side jacket part formed in the cylinder block, and circulates cooling water through a cooling water path formed through the water jacket. A device for cooling the engine
While the engine is warming up, the flow of the cooling water in the head side jacket portion is allowed, while the flow of the cooling water in the block side jacket portion is blocked, and the cooling water is passed through the head side jacket portion. A flow path switching device for circulating
When the flow in the block side jacket portion is blocked by the flow path switching device, the flow rate of the cooling water flowing through the head side jacket portion is set to the temperature rise of the cylinder head during warm-up. A flow restriction device that restricts to a small amount when the temperature is low compared to when the temperature is high,
Engine cooling system composed of including. As a water jacket inside the engine, it has a head side jacket part formed in the cylinder head and a block side jacket part formed in the cylinder block, and the cooling water is circulated through the cooling water path formed through the water jacket. A device for cooling the engine
While the engine is warming up, the flow of the cooling water in the head side jacket portion is allowed, while the flow of the cooling water in the block side jacket portion is blocked, and the cooling water is passed through the head side jacket portion. A flow path switching device for circulating
When the flow in the block side jacket portion is blocked by the flow rate switching device, the flow rate of the cooling water flowing through the head side jacket portion is set to the cooling of the cylinder head at a normal time after the engine warm-up is completed. A flow restriction device that restricts the amount to less than the amount assigned to
Engine cooling system composed of including.   The engine cooling device according to claim 2, wherein the flow restriction device increases the flow rate of the cooling water in response to an increase in temperature of the cylinder head.   The flow rate limiting device includes a water temperature sensor arranged to be able to detect a local temperature of the cooling water flowing through the head side jacket portion, and limits the flow rate of the cooling water based on a temperature detection value of the water temperature sensor. The engine cooling device according to claim 1 or 3.   The said water temperature sensor is installed so that the temperature of the cooling water of the part formed in the periphery of the exhaust port located in the most downstream side with respect to the flow of the cooling water in the said cylinder head among the said head side jacket parts can be detected. 4. The engine cooling device according to 4. The flow restriction device is
A flow control valve installed on the upstream side of the water jacket in the cooling water path;
A device for controlling an opening area of the flow control valve;
The engine cooling device according to claim 1, comprising: The flow restriction device is
A water pump configured to vary the discharge amount, and installed in the cooling water path upstream of the water jacket;
A device for controlling the discharge amount of the water pump;
The engine cooling device according to claim 1, comprising:   The flow path switching device releases the block of the flow in the block side jacket portion after the cylinder head has been heated to a predetermined temperature or higher, and passes both the head side jacket portion and the block side jacket portion. The engine cooling device according to any one of claims 1 to 7, wherein the cooling water is circulated. In the cooling water path, the water jacket is included in part, and an annular circulation path forming the cooling water path during engine warm-up, and the circulation branching off from the circulation path downstream of the water jacket The engine cooling device according to any one of claims 1 to 8, wherein a detour that extends in parallel with the road and joins the circulation path on the upstream side of the water jacket is provided,
A radiator interposed in the detour;
Arranged at the junction of the circulation path and the bypass route, the coolant flow from the bypass route to the circulation passage is shut off during engine warm-up, while the cylinder head and the cylinder block rise above a predetermined temperature. A shut-off valve that allows inflow from the detour after warming;
A flow rate control valve that reduces the flow rate of the flowing cooling water to a smaller amount than after the predetermined period has elapsed over a predetermined period after the temperature rise;
An engine cooling system.

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