KR20010113100A - Oil level measurement by using unsteady hot-wire method - Google Patents

Abstract

The present invention relates to an oil level measuring method using an abnormal hot wire method, and an object thereof is to accurately measure the oil level regardless of whether or not the engine is operated.

The present invention for achieving the above object, the measurement voltage of the oil contact length (Ll) section having a first resistance (Rl) always in contact with only the oil relative to the oil surface in the state that the conductor is installed inside the oil pan Gas contact voltage (Vg), which is a measurement voltage of the gas contact length (Lg) section having a phosphorus oil contact voltage (Vl) and a fourth resistance (Rg) which always comes into contact only with the gas, and a second contact with oil and gas at the same time. Divided into variable contact voltage (Vi), which is the measured voltage of the variable contact length (Li) section with resistance (Rli, Rgi), and the wire submerged in the oil surface based on the oil surface to measure the temperature difference of the conductor. The oil contact lead temperature (Twl), which is the measured temperature of, and the temperature of the conductor exposed to oil, which is the measured temperature of the conductor exposed to the oil surface by being exposed to the oil surface, are divided into the gas contact lead temperature (Twg). Variable contact length (Li) section whose value changes with nothing The oil level change in the oil pan is measured using the oil contact voltage (Vl) between the variable contact voltage (Vi) and the oil contact length (Ll) and the gas contact voltage (Vg) between the gas contact length (Lg). It features.

Description

Oil level measurement by using unsteady hot-wire method

The present invention relates to an oil level measuring method using an abnormal hot wire method, and more particularly, to an oil level measuring method using an abnormal hot wire method that enables the oil level to be measured regardless of whether the engine is operated or not. .

In general, the lack of lubricant in the engine of the vehicle will cause fatal damage to the operation of the engine, so various methods are usually used to warn the driver of the lack of lubricant and to measure the oil level of the lubricant to compensate for the lack.

The most common method of measuring the oil level is to measure the level using the oil pressure in the main gallery. When the measured oil pressure is lower than the set reference value, the oil pressure in the main gallery is measured. The driver will be warned, but if it is judged whether oil has been replenished due to the drop in oil pressure, the parts (e.g., bearings, etc.) are already In many cases, after the engine is damaged, the rotation speed of the oil pump is low, so there is no difference in oil pressure regardless of the amount of oil. Therefore, it is fundamentally impossible to measure the oil level by measuring the oil pressure. Will be.

In addition, in the case of partial load, since the oil pressure varies depending on the rotational speed and the amount of oil, there is a disadvantage in that it is very difficult to obtain the oil level through measurement of the changed oil pressure.

In order to overcome this disadvantage, a level gauge method using a semiconductor or an ultrasonic wave may be used to directly measure the level of oil in the oil pan. However, such a method may be installed due to the nature of the oil pan having a high internal temperature. However, there are a lot of restrictions on mounting.

In addition, it is possible to use a method of measuring the oil level by measuring the temperature difference between the oil temperature and the gas inside the oil pan generated when the engine is operating, but this method using the temperature difference is the oil when the engine is not running Since there is no difference between the temperature of the gas and the gas temperature, there is a fundamental problem that the oil level cannot be measured using the temperature difference between the oil and the gas.

Accordingly, the present invention has been made in view of the above, and an object thereof is to enable the oil level to be accurately measured regardless of the operation of the engine.

The present invention for achieving the above object, the first resistance is always in contact with the oil only on the basis of the oil surface in the state in which the conductor is installed to measure the voltage difference due to the difference in contact between the oil and the gas inside the oil pan ( Gas contact which is the measured voltage between the oil contact voltage Vl, which is the measurement voltage of the oil contact length Ll section having Rl), and the gas contact length Lg, which has the fourth resistance Rg, which always comes into contact only with the gas. The voltage Vg and the variable contact voltage Vi, which are measured voltages of the variable contact length Li section having the second and third resistors Rli and Rgi which are in contact with the oil and the gas at the same time, are divided into the oil pans. In order to measure the temperature difference between the conductors due to the difference in contact between the oil and the gas, the oil contact conductor temperature (Twl), which is the measurement temperature of the conductor submerged in the oil surface with respect to the oil surface, and the lead exposed to the gas Wire exposed to oil, the measured temperature of Is divided by the gas contact lead temperature (Twg), and the variable contact voltage (Vi) between the variable contact length (Li) where the value is changed by the conductor heated or cooled according to the presence or absence of current. The oil level change in the oil pan is measured based on the oil contact voltage Vl of the oil contact length Ll section and the gas contact voltage Vg of the gas contact length Lg section.

1 is a schematic diagram showing the principle of the oil level measurement method using the abnormal heating method according to the present invention

Figure 2 is a state diagram of the oil level measured by heating the conductor in accordance with the present invention

Figure 3 is a state diagram of the oil level measured by cooling the wire in accordance with the present invention

4 is a flow chart of the oil level according to FIG.

5 is a flow chart of measuring the oil level according to FIG.

<Description of the symbols for the main parts of the drawings>

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows a schematic diagram showing the principle of the oil level measurement method using the abnormal hot wire method according to the present invention, in order to measure the voltage difference due to the difference in contact between the oil and the gas inside the oil pan according to the present invention The oil resistance voltage Vl, which is a measurement voltage of the oil contact length Ll section having the first resistance Rl that always contacts only oil with respect to the oil surface with the conductor installed, and the fourth resistance that always contacts only the gas. Variable contact length (Li) having a gas contact voltage (Vg), which is a measurement voltage of the gas contact length (Lg) section having (Rg), and second and third resistors (Rli, Rgi) simultaneously contacting oil and gas. The measured temperature of the wire submerged in the oil surface based on the oil surface to measure the temperature difference of the conductor due to the difference in contact between the oil and the gas inside the oil pan. Oil contact lead temperature (Twl) The temperature of the wire part exposed to the oil, which is the measurement temperature of the wire exposed to the surface and in contact with the gas, is divided by the gas contact wire temperature (Twg), and the wire is heated or cooled according to the presence or absence of current. The oil contact voltage (Vl) of the variable contact length (Li), oil contact length (Ll), and gas contact voltage (Vg) of the gas contact length (Lg) of the variable contact length (Li) section where the value is changed are mediated. This will measure the amount of oil level change inside the oil pan.

Here, this principle uses a temperature rising rate that varies with time according to the natural convection coefficient of the surrounding fluid when the conductor is heated by applying a current to the conductor, that is, the temperature of the conductor according to the heat generation of the conductor in which convective heat transfer occurs on the surface. Can be obtained from the following equation (1).

q-hconv A (Ts-T _∞ ) = ρCp (dTs / dt) (π / 4) D ² l ------- (1)

Where q: calorific value, hconv: convective heat transfer coefficient, A: surface area of the conductor

Ts: temperature of lead, T _∞ : temperature of fluid, ρ: density of lead

Cp: specific heat of the conductor, t: time, D: diameter of the conductor, l: length of the conductor

Therefore, if the amount of heat generated minus the amount emitted to the surface is stored in the wire to raise the temperature of the wire or if the amount of heat generated is less than the amount emitted to the surface, the temperature of the wire is lowered.

In addition, the resistance of the metal which changes with temperature can be calculated | required from following formula (2).

R (T) = R0 (1 + a _w T) ------------------ (2)

Where R = resistance, R0: resistance at reference temperature, a _w : temperature resistance coefficient,

T: temperature

However, for metals, the temperature resistance coefficient is positive.

Therefore, if the current of the same magnitude is flowed from the equations (1) and (2) to the conductors always in contact with the air in the oil pan and the conductors always in contact with the oil, the temperature between the two conductors is different due to the difference in the convection heat transfer coefficient Therefore, it can be seen that the voltage difference between the resistance of the wire and the both ends of the wire is different.

As such, when the conductor is heated, the temperature, resistance, and voltage of the conductor are changed according to the fluid characteristics around the conductor, and according to the present invention, a constant current (I) is applied to the conductor bounded by the oil surface inside the oil pan. When flowing or blocking, as shown in Figures 2 and 3, the temperature difference between the conductor submerged in the oil and the conductor in contact with the gas without being submerged in oil based on the oil surface.

That is, as shown in FIG. 2, when the current is heated through the wire, the difference in temperature between the two wires can be seen to be large as time elapses. At this time, the heating is performed to measure with excellent sensitivity and a small measurement error. Of course, it is measured after the dead time (t ') after a certain time has passed.

In addition, when the conductor is cooled by cutting off the current, the temperature difference between the two conductors disappears as time passes, so that the temperature becomes the same.

Therefore, as shown in the present invention, when a constant current I flows through the conductor located on the boundary line of the oil surface inside the oil pan, the resistance R1, Rg, Rli, and Rgi provided in each section of the conductor The voltages Vl, Vg, and Vi of each of the sections L1, Lg, and Li are dropped, and a relational expression thereof is expressed by the following equation (3).

Vg = I.Rg = I.P.Lg / A x (1 + a _w Twg)

Vi = I.Rgi + I.Rli = I.P. (Li-h) / A x (1 + a _w Twg)

+ IPh / A x (1 + a _w Twl) ---- (3)

Vl = IRl = IPLl / A x (1 + a _w Twl)

Here, P is the resistance coefficient, A is the cross-sectional area of the conductor, h is the oil level is the length of the third resistance (Rgi) section in contact with the oil of the variable contact length (Li) section in contact with the oil and gas at the same time.

In addition, the relationship between the resistance and the resistance coefficient is expressed by the following equation (4).

R = P (L / A) ---------------- (4)

Therefore, the oil level h from equations (3) and (4) is expressed by the following equation (5).

Vi / Li-Vg / Lg

h = Li x --------------- ---------------- (5)

Vl / Ll-Vg / Lg

If the length of each section of the conductor is the same as Ll = Lg = Li = L, equation (5) is expressed by the following equation (6).

Vi-Vg

h = L x -------- ---------------- (6)

Vl-Vg

Therefore, the oil level to be measured can be measured through Eq. (5) or Eq. (6) expressed as the voltage difference caused by the difference in the length of the conductor in contact with and non-contact between oil and gas inside the oil pan. do.

In addition, the present invention has a feature that can measure the oil level irrespective of whether the engine is operating, which is, for example, the current flows or is blocked in the lead wire according to whether or not the operation of the engine is heated wire Or cooled.

FIG. 4 illustrates a case in which a conductor is heated by applying a current to the conductor, in which case, first, an oil contacting conductor temperature Twl of the conductor submerged in the oil surface and the oil of the conductor exposed to the oil surface are in contact with the gas. It is determined whether the contact lead temperature Twg satisfies the equilibrium condition, and when the equilibrium condition of the two temperatures Twl and Twg is satisfied, the current is energized so that the dead time t 'is shown in FIG. 3. After that, the voltages (Vl, Vg, Vi) of the conductors are simultaneously measured and converted into digital.

Then, when the voltage (Vl, Vg, Vi) converted to digital is equal to Eq. (5) or the length (Ll, Lg, Li = L) of each section is equal to each other, the oil level (h) is expressed using Eq. (6). Get it and mark it to the driver.

In addition, FIG. 5 shows the characteristics as shown in FIG. 3 as the current of the conductor is blocked. In this case, first, the gas contact conductor temperature (Twg) and the oil surface of the conductor exposed to the oil surface and in contact with the gas. Based on this, it is determined whether the condition that the difference in the oil contact lead temperature (Twl) of the conductor submerged in the oil surface is greater than the preset lead temperature (Ts) is satisfied, and the current is cut off when the set temperature (Ts) of the lead is small. By measuring the voltage (Vl, Vg, Vi) of the wire at the same time and converts it to digital.

Then, when the voltages (Vl, Vg, Vi) converted to digital are equal to Eq. (5) or the lengths (Ll, Lg, Li = L) of each section are equal to each other, the oil level (h) is expressed using Eq. (6). Will be saved and displayed to the driver.

At this time, in order to increase the accuracy of the measurement, it is a matter of course to determine the moment when the temperature difference (Twg-Twl) between the two conductors is large.

As described above, according to the present invention, the oil through the inside of the oil pan in which the oil and the air occupied section coexist by using the difference in temperature rise rate according to the natural convection coefficient of the fluid around the conductor generated according to whether or not the current conduction of the conductor Since the oil level is measured, the oil level can be accurately measured regardless of the engine operation.

Claims (7)

Based on the oil surface inside the oil pan where oil and gas occupy coexist, it is submerged in oil and takes advantage of the natural convection generated from the fluid around the conductor heated or cooled according to the presence or absence of current flow in the conductor exposed to the gas. Oil level measurement method using the abnormal hot wire method to measure the oil level. 2. The oil contact voltage (Vl), which is the measurement voltage of the oil contact length (Ll) section having the first resistance (Rl) that always contacts only the oil, is always at the gas Variation with gas contact voltage (Vg) which is the measured voltage of gas contact length (Lg) with fourth resistance (Rg) in contact and second and third resistors (Rli, Rgi) in contact with oil and gas at the same time Measure by dividing by the variable contact voltage (Vi) which is the measured voltage of the contact length (Li) section, Subsequently, in order to measure the temperature difference of the conductor due to the difference in contact between the oil and the gas inside the oil pan, the oil contact lead temperature (Twl), which is the measurement temperature of the conductor submerged in the oil surface with respect to the oil surface, is exposed to the Measures the temperature of the wire part exposed to oil, which is the measurement temperature of the wire in contact with the gas, by using the gas contact wire temperature (Twg). Subsequently, the dropped voltages Vl, Vg and Vi of the respective sections Ll, Lg, and Li are calculated according to the resistances Rl, Rg, Rli, and Rgi provided in each section of the conductive line, and then Vg = I.Rg = I.P.Lg / A x (1 + a _w Twg) Vi = I.Rgi + I.Rli = I.P. (Li-h) / A x (1 + a _w Twg) + IPh / A x (1 + a _w Twl) Vl = IRl = IPLl / A x (1 + a _w Twl) Where, P: resistance coefficient, A: cross sectional area of the wire, h: the oil level, a _w: a temperature coefficient of resistance. Subsequently, using the relation R = P (L / A) of resistance and resistance coefficient in the voltage drop equation, Vi / Li-Vg / Lg h = Li x --------------- Vl / Ll-Vg / Lg or Vi-Vg h = L x -------- (if equal interval length Ll = Lg = Li = L) Vl-Vg Oil level measurement method using the abnormal hot wire method, characterized in that to calculate the oil level (h). 3. The method of claim 2, wherein the voltages Vl, Vg, and Vi dropped for each section Ll, Lg, and Li of the conductive line are simultaneously measured. The oil level measurement method according to claim 2, wherein a current flows through the conductive wires in a state where the oil contact lead temperature Twl and the gas contact lead temperature Twg are in equilibrium with each other. 5. The method of claim 4, wherein the dropped voltages (Vl, Vg, Vi) of the lead wire are measured after a dead time (t '). The abnormal hot wire method according to claim 2, wherein the current is cut off when the difference between the oil contact lead temperature Twl and the gas contact lead temperature Twg becomes larger than a predetermined lead temperature Ts. Oil level measurement method using. 7. The method of claim 6, wherein the temperature difference between the two wires (Twg-Twl) is a point at which the wires are formed largely due to the characteristics of the wires.