JPS6210416A - Freeze preventing device of evaporative cooling type internal-combustion engine - Google Patents

Abstract

PURPOSE:To restrain antifreeze components from uneven distribution so as to prevent a condenser or the like from breakdown due to freezing, by providing a refrigerant mixing mechanism in order to forcingly mix the specified amount of liquid-phase refrigerant staying in a water jacket into vapor flow running from said jacket toward a condenser. CONSTITUTION:In the case of the device stated in the title, liquid-phase refrigerant stored up to the specified level in a water jacket 2 is heated during the operation of an internal-combustion engine 1, and the internal-combustion engine 1 is cooled by taking heat away when the refrigerant is boiled and vaporized. Then, the produced refrigerant vapor is cooled and condensed in a condenser 8, stored in a lower tank 18, and forced to flow back to the water jacket 2 by the operation of a refrigerant supply tank 16. In this case, a passage 31 for refrigerant mixing is made to diverge from a heater outlet passage 29, being selected out of passages 28 and 29 through which the liquid-phase refrigerant is circulated between the water jacket 2 and a heater core 26 for heating. The other edge of the passage 31 is connected to the upperstream side of a vapor passage 10 so as to enable the specified amount of the liquid-phase refrigerant to be mixed into the refrigerant vapor in the vapor passage 10.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a boiling-cooled internal combustion engine that performs cooling by utilizing the boiling and condensing cycle of a liquid phase refrigerant stored in a water jacket, and particularly relates to The present invention relates to an antifreeze device that prevents freezing due to uneven distribution of antifreeze components.

Conventional Technology As a cooling device for an internal combustion engine, a boiling cooling device that utilizes the boiling and condensing cycle of a refrigerant (cooling water) was proposed in Japanese Patent Publication No. 57-57608, etc., in place of the conventional water-cooled cooling device. However, the present applicant has already filed various applications (e.g., JP-A-59-180023, JP-A-60-3) to develop this further and to put it into practical use.
6715, Japanese Patent Application No. 59-100156, Japanese Patent Application No. 59-140378, etc.). This consists of a water jacket in which liquid phase refrigerant is stored up to a predetermined level, a condenser connected via a steam passage to the steam outlet at the top of this water jacket, and a water jacket connected to the water jacket from the bottom of the condenser where liquefied refrigerant is temporarily stored. A closed refrigerant circulation system is formed mainly by a refrigerant supply pump that circulates and supplies liquid refrigerant to the jacket. While the refrigerant liquid level in the water jacket is monitored by a liquid level sensor during engine operation, the refrigerant supply pump is controlled to maintain the liquid level at a predetermined level. It was designed to be maintained at

According to a boiling cooling device that utilizes the latent heat accompanying the phase change of the refrigerant, the heat exchange efficiency can be dramatically improved, and each part can be uniformly cooled to the refrigerant boiling point.

Problems to be Solved by the Invention By the way, as a refrigerant for this type of boiling cooling device, ethylene glycol or propylene glycol is mixed with water as an antifreeze liquid in view of ease of handling, large latent heat of vaporization, cost, etc. It has been considered to use an aqueous solution of ethylene glycol with some rust inhibitor added, but for example, since an aqueous solution of ethylene glycol is a non-azeotropic mixture, the vapor of the aqueous solution contains almost no ethylene glycol. There is no water vapor, only water vapor. For example, the vapor of a 50% (weight %) aqueous solution of ethylene glycol contains only about 2% ethylene glycol.

Therefore, when the boiling cooling device described above is continuously operated, a large amount of ethylene glycol is unevenly distributed in the water jacket, and the ethylene glycol concentration becomes extremely low on the condenser side. Therefore, there is a risk that the capacitor may freeze inside the capacitor during the winter, damaging the capacitor, or that the solenoid valve or refrigerant supply pump may freeze and malfunction.

In particular, when boiling continues for a long time under operating conditions such as low speed and low load, where the amount of refrigerant carried out as droplets along with the flow of steam generated in the water jacket is small, the above-mentioned antifreeze components are unevenly distributed. occurs significantly.

Means for Solving the Problems This invention aims to reliably prevent freezing due to uneven distribution of antifreeze components in the refrigerant as described above, by converting the liquid phase refrigerant in the water jacket into a vapor flow from the water jacket to the condenser. In addition to providing a refrigerant mixing mechanism that forcibly mixes the refrigerant, the amount of refrigerant (L) that flows into the condenser along with the vapor flow is determined by the liquid conversion capacity ratio (
The present invention is characterized in that the amount of liquid phase refrigerant mixed in the refrigerant mixing mechanism is set so that L/W) is 4 or more.

As a result of boiling of the refrigerant, the concentration of ethylene glycol and propylene glycol, which are antifreeze components in the working refrigerant, becomes higher on the water jacket side and lower on the condenser side, as described above. The refrigerant mixing mechanism prevents uneven distribution of antifreeze components by forcibly entraining the refrigerant in the water jacket, which has a high antifreeze concentration, into the vapor flow and flowing it into the condenser together with the vapor. By keeping the liquid equivalent capacity ratio (L/W) between the amount of refrigerant flowing into the condenser (L) and the amount of vapor generated (W) at 4 or more, the concentration of antifreeze can be maintained within a range that can reliably prevent freezing. I can do it.

Figure 2 shows the ethylene glycol concentration in a boiling-cooled internal combustion engine for small automobiles when boiling is performed using a so-called long-life coolant (LLC), which is an aqueous ethylene glycol solution with a small amount of rust preventive added, as the refrigerant. This shows experimental data examining the uneven distribution of . The initial concentration is 50% of the cold region specification, and when the operation is performed for a few minutes to more than ten minutes and boiling and condensation occurs, an equilibrium state is reached when the concentrations in the water jacket and condenser change to a certain extent. Become. Figure 2 is organized by taking the equilibrium concentration on the vertical axis and the liquid equivalent volume ratio L/W between the amount of ethylene glycol aqueous solution accompanying the vapor flow and the amount of generated vapor (condensation amount) W on the horizontal axis. As is clear from the figure, if the capacity ratio L/W is 4, the uneven distribution of ethylene glycol is suppressed to about +4% and -3%, and if the L/W is larger than this, the uneven distribution is suppressed. Become even smaller. Moreover, when L/W becomes 4 or less, the uneven distribution suddenly becomes noticeable.

FIG. 3 shows simulation results organized by factors that affect such concentration imbalance. This is based on the assumption that when an aqueous ethylene glycol solution boils, it becomes only pure water or steam (in reality, 50% ethylene glycol
Approximately 2% ethylene glycol becomes vapor in an aqueous solution, but
The effect is small, so ignore it. ), and assuming that this water vapor is accompanied by an ethylene glycol aqueous solution, how the initial concentration of 50% is biased and what percentage equilibrium concentration is reached can be calculated using a simultaneous differential equation (however, the concentration on the Cc dicondenser side (x 100 %), C
E: engine side 1 degree, vc: condenser side aqueous solution amount, v
E: Amount of aqueous solution on the engine side, I: Amount of entrained aqueous solution, W: Amount of generated steam (amount of condensation)). That is, the ratio L/W of the amount of entrained ethylene glycol aqueous solution to the amount of water vapor generated W and the engine side aqueous solution i! vE and the amount of aqueous solution on the condenser side v
Equilibrium concentration can be arranged using the ratio VE/l/C to c, and the vertical axis in FIG. 3 is the equilibrium concentration, the horizontal axis is the ratio VE/Vc, and the parameter in the figure is the ratio L/W. From this figure, it can be seen that when the amount of entrained liquid is small (L/W is small), the concentration is biased greatly.
It is clear that the larger E/Vc, the greater the leanness on the capacitor side and the smaller the change on the engine side.

However, when considering this VE'/Vc and the danger of freezing of the condenser, the amount of aqueous solution ME on the engine side is equal to the capacity ゛ below the set level of the water jacket, and the aqueous solution IVc on the condenser side is In a configuration that changes the heat dissipation capacity,
When the outside temperature is low, most of the inside of the capacitor is considered to be occupied by the liquid phase refrigerant region in order to control the heat dissipation capacity, so in practical use 0.9< VE for internal combustion engines for small automobiles.
/VC<1.3. Therefore, the third
As shown in the figure, within this range, if L/W is maintained at 4 or more, concentration deviation can be suppressed to within about 50±6%, and a freezing temperature of -30°C can be ensured.

In this way, the experimental results shown in FIG. 2 above agree with the simulation results that analyzed the factors.

That is, the liquid phase refrigerant is forcibly introduced by the refrigerant mixing mechanism so that the liquid conversion ratio (L/W) between the refrigerant liquid 1i (L) accompanying the vapor flow and the amount of generated vapor (W) is maintained at 4 or more. By entraining it, freezing caused by uneven distribution of ethylene glycol concentration can be reliably prevented.

Incidentally, since the propylene glycol aqueous solution also has non-azeotropic properties similar to the ethylene glycol aqueous solution, substantially the same results as in FIGS. 2 and 3 are obtained.

FIG. 4 and FIG. 5 show phase diagrams of an ethylene glycol aqueous solution and a propylene glycol aqueous solution, respectively.

Embodiment FIG. 1 shows a boiling-cooled internal combustion engine equipped with an antifreeze device according to the present invention.

The water jacket 2 provided in the internal combustion engine main body 1 is
It is formed across both the cylinder block 3 and the cylinder head 4, and a plurality of steam outlets 5 are provided in the upper part thereof. In this water jacket "KERAT 2", a liquid phase refrigerant consisting of, for example, an aqueous ethylene glycol solution is in the first state.
The liquid is stored up to a set level determined by a liquid level sensor 6, and a temperature sensor 7 is mounted below the set level.

The condenser 8 includes an upper tank 11 that communicates with the steam outlet 5 of the water jacket 2 via a steam manifold 9 and a steam passage 10, a core section 12 mainly composed of fine tubes extending in the vertical direction, and It consists of a lower tank 13 that temporarily stores condensed liquefied refrigerant, and an electric cooling fan 1 for forced cooling on the back side.
It is equipped with 4. The lower tank 13 is connected to the water jacket 2 via a refrigerant circulation passage 15, and an electric refrigerant supply pump 16 is interposed in the refrigerant circulation passage 15. The refrigerant supply pump 16 operates intermittently based on the detection signal of the first liquid level sensor 6, and supplies the refrigerant from the condenser 8 to the water jacket 2 so as to keep the refrigerant liquid level in the water jacket 2 near a set level at all times. This replenishes liquid phase refrigerant. Note that a second liquid level sensor 17 is installed in the lower tank 13 to detect the presence or absence of liquid phase refrigerant.
is provided.

Above water jacket 2. The condenser 8, the refrigerant circulation passage 15, and the refrigerant supply pump 16 constitute a refrigerant circulation system that is normally kept in a sealed state from which air is removed, and the refrigerant circulates within the system while repeating a cycle of boiling and condensation. become.

In addition, 21 is a reservoir tank provided outside the refrigerant circulation system, and includes a normally open type solenoid valve 22 and a three-way type solenoid valve that can be switched between "flow path A" and "flow path B" as shown in the figure. 23
The liquid phase refrigerant can be introduced and discharged between the lower tank 13 and the condenser 8 through the
Variable control of heat dissipation capacity is possible. Moreover, 24 is an air exhaust passage provided with a normally closed electromagnetic valve 25.

On the other hand, 26 indicates a heater core for heating provided in the vehicle interior, and the upper refrigerant inlet is connected to the heater core inlet passage 26.
The lower refrigerant outlet is connected to the cylinder block 3 side of the water jacket 2 via the heater outlet passage 29.
It is connected to the cylinder head 4 side via. 30 is a heater pump installed in the heater outlet passage 29 to circulate liquid phase refrigerant between the water jacket 2 and the heater core 26, and is operated in conjunction with a heater switch (not shown). The structure is as follows. On the discharge side of the heater pump 30, a refrigerant mixing passage 31 is branched from the heater outlet passage 29.
And its tip is connected to the upstream side of the steam passage 10. That is, in this embodiment, the heater pump 30 and the refrigerant mixing passage 31 constitute a refrigerant mixing mechanism. In addition, 32 is a three-way solenoid valve that can be switched to "flow path C" and "flow path DJ." It is now possible to do so.

In the above configuration, since heating is always required in winter when there is a risk of freezing, the heater pump 30 is driven, and at that time, the liquid phase refrigerant returns from the heater core 26 to the water jacket 2. A part of the refrigerant is led to the steam passage 10 through the refrigerant mixing passage 31 and sent to the condenser 8 along with the steam flow. Here, the flow rate of the liquid phase refrigerant to be mixed into the vapor flow is set so that the liquid equivalent capacity ratio L/W between the entrained refrigerant liquid amount and the generated vapor amount W is always 4 or more, as described above. There is. Specifically, when the amount of refrigerant that is naturally carried out with the steam flow is small, that is, under operating conditions where the heat load of the engine is small, a flow rate of about four times the amount of generated steam is secured. The passage diameter, passage length, orifice diameter, etc. of the refrigerant mixing passage 31 are set, and when the heat load is large, the L/W is set to 4 due to the increase in the amount of entrained refrigerant that is naturally carried out by the vapor flow.
The configuration is such that the above state is maintained continuously. Incidentally, in an automobile engine with a total displacement of around 2000 cc, the flow rate of the refrigerant to be mixed through the refrigerant mixing passage 31 is II2/
This is a relatively small amount that is less than a win. If a flow rate of more than four times the maximum steam generation amount is given only with the refrigerant that is forcibly mixed in, the amount of naturally generated entrained refrigerant will increase and the amount of circulation will increase more than necessary, resulting in a decrease in the performance of the condenser 8, etc. This is not desirable because it causes

Effects of the Invention As is clear from the above explanation, the antifreeze device for boiling-cooled internal combustion engines according to the present invention can suppress the uneven distribution of antifreeze components to an extremely small range, and prevent damage to capacitors due to freezing even in extremely cold regions. It is possible to reliably prevent malfunctions of refrigerant supply pumps, etc.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the configuration of a boiling-cooled internal combustion engine equipped with an antifreeze device according to the present invention, and Fig. 2 is a characteristic showing the results of an experiment on the relationship between the equilibrium concentration of ethylene glycol concentration and the capacity ratio L/W. 3 and 3 are characteristic diagrams showing the simulation results of analyzing factors that influence the concentration, and FIGS. 4 and 5 are state diagrams of an ethylene glycol aqueous solution and a propylene aqueous solution. 2...Water jacket, 8...Capacitor, 1
0... Steam passage, 16... Refrigerant supply pump, 26.
... Heater core, 30 ... Heater pump, 31 ...
・Refrigerant mixing passage. Figure 2 1) I cow LLC/shi 25 creation, t/departure ^(ru i amount (
This is the third figure.

Claims (1)

[Claims] (1) A water jacket in which a liquid-phase refrigerant consisting of an aqueous ethylene glycol solution or an aqueous propylene glycol solution is stored up to a predetermined level, a condenser into which the refrigerant vapor generated in this water jacket is introduced, and a space between this condenser and the water jacket. is located in
and a refrigerant supply pump that replenishes liquid phase refrigerant from the condenser to the water jacket so as to maintain the refrigerant liquid level in the water jacket at the predetermined level. A refrigerant mixing mechanism is provided that forcibly mixes the phase refrigerant into the vapor flow from the water jacket to the condenser, and the liquid refrigerant amount (L) flowing into the condenser along with the vapor flow and the amount of generated vapor (W) are mixed. Converted capacity ratio (L
1. A freeze prevention device for a boiling-cooled internal combustion engine, characterized in that the amount of liquid phase refrigerant mixed in the refrigerant mixing mechanism is set so that /W) is 4 or more.