JPH0218137A - Controlling method for automatic defroster - Google Patents

Abstract

PURPOSE:To properly control a defroster always independently of changes in the number of passengers, air-conditioning, season, etc. by driving the defroster when the output of dew condensation sensors reached either of a specific operational value or upper limit value after exceeding a specific threshold limit value. CONSTITUTION:Dew condensation on the front and rear windshields 1, 3 is removed by controlling, with a control part 5, the front and rear defroster driving parts 6 and 7, based on each output of the front and rear dew condensation sensors, 2 and 4, which are respectively installed on the front and rear windshields 1, 3 of an automobile. At the control part 5, then, an operational value is set with the initial value of each dew condensation sensor, 2 and 4, as a reference value when the electric source was turned on. The saturated humidity of each dew condensation sensor, 2 and 4, is set as the upper limit value while an output value of each dew condensation sensor, 2 and 4, corresponding to the lowest humidity required for the generation of dew condensation is set as the lower limit value. Each defroster driving part, 6 and 7, is operated when the output of each dew condensation sensor 2 and 4, reached either of the operational value or the upper limit value after exceeding the lower limit value.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for automatically driving a defroster and a heat wire provided as an anti-fog device on the windshield and rear glass of an automobile.

[Conventional technology]

A conventional automatic defrosting device called an auto defroster is known to turn on or off power to a heating wire disposed on a rear window based on a change in the resistance value of a dew condensation sensor, for example.

[Problem to be solved by the invention]

However, the above-mentioned conventional methods are not compatible with the complex environment that occurs in a car, such as changes in the humidity inside the car due to the number of occupants, changes in the temperature inside the car due to heating and cooling equipment, and changes in the outside environment due to weather changes such as seasonal changes and rainfall. Changes are not taken into account, and it is not possible to respond to all the changes mentioned above.For this reason, the defroster drive may be canceled before the condensation has been removed, or even when no condensation has occurred. This results in the inconvenience that the defroster is driven regardless of the condition, and the development of a solution to this inconvenience has been a challenge.

[Means to solve the problem]

As a specific means for solving the conventional problems described above, the present invention includes a dew condensation sensor disposed on a windshield of an automobile, a control section for processing signals from the dew condensation sensor, and a control section for processing signals from the condensation sensor. and a drive unit that drives the defroster based on a signal, and the control unit calculates an initial value at power-on when the condensation sensor starts operating as a reference value and sets an operating value, and also controls humidity saturation of the dew condensation sensor. value as a lower limit value, the output value of the dew condensation sensor corresponding to the lowest humidity required for condensation to occur on the window glass is held as the lower limit value, and the output from the dew condensation sensor exceeds the lower limit value and the operating value Alternatively, a method for controlling an auto defroster is characterized in that when any of the lower limit values is reached, an operation signal is issued to the drive unit to drive the defroster, and the dew condensation state is eliminated from the start of the operation of the defroster. A stop value is set as the elapsed time or the output value of the dew condensation sensor using the elapsed time as a coefficient, and when the output value of the dew condensation sensor reaches the stop value, a stop signal is issued to the drive unit to activate the defroster. The above-mentioned conventional problems are solved by providing a method for controlling an auto defroster, which is characterized by stopping the auto defroster.

【Example】

Next, the present invention will be explained in detail based on an embodiment shown in the drawings. FIG. 1 is a block diagram showing the auto defroster control method of the present invention, in which a front dew condensation sensor 2 is attached to a windshield 1, a rear dew condensation sensor 4 is attached to a rear glass 3, and both of the above dew condensation sensors are attached. Both outputs 2 and 4 are input to the control section 5. The control unit 5 calculates the input from the dew condensation sensor 2.4, and detects dew condensation on the windshield 1 and rear glass 3, respectively, according to the result, and corresponds to the glass 1.3 on the side where dew condensation is detected. Either or both of the defroster drive unit 6 and the rear defroster drive unit 7 are operated to perform an anti-fog action. Even during the operation of the defroster drive units 8 and 7, the calculation by the control unit 5 of the dew condensation sensor 2.4 is continued, the effect of driving the defroster is monitored, and the value of the dew condensation sensor 2.4 reaches a predetermined value. Sometimes, the operation of the defroster drive section 6.7 is stopped, assuming that the anti-fogging action has been completed. As is clear from the above explanation, the control method of the present invention is not only applied to the hot wire installed on the rear glass 3 as in the conventional example, but also applies to a windshield defroster device using air blowing from an automobile's heating/cooling system, etc. It also makes it possible to operate both at the same time. The gist of the present invention will be explained in more detail below. Here, the dew condensation sensors 2 and 4 are conventionally used, for example, two electrodes are disposed close to the glass surface, and the resistance value between the electrodes is reduced by water droplets adhering to the glass surface. Any type of sensor can be used, such as a parallel line sensor that detects the resistance using a sensor that detects moisture, or a sensor that is made of a mixture of resin that expands when it absorbs moisture and conductive particles, and whose resistance value increases when it absorbs moisture. FIG. 2 shows the principle of starting the drive by the control section 5 of the present invention when the dew condensation sensor 2.4 is selected to have a resistance that increases with humidity. Since both are processed using the same principle at the start of driving, only the front dew condensation sensor 2 will be described. According to the results of the study conducted by the inventor to realize this invention, the front dew condensation sensor 2 (hereinafter abbreviated as sensor 2) is as follows:
For example, when the power is turned on to start operation, the resistance value is set to the atmospheric humidity at that time as an initial value, and changes depending on the state from this initial value. The characteristic line and the characteristic line H in Fig. 2 specifically show this.For example, the characteristic line shows the characteristic when the atmospheric humidity is low, and the initial value at the start of measurement is A□. Yes, as the humidity of the glass surface increases, the resistance value decreases to B.
, to rise to. Similarly, the characteristic line H is obtained when the above-mentioned atmospheric humidity is high, and the initial value is A2, and the resistance value increases to B2 as the humidity of the glass surface increases. From the above results, for example, the method of setting the operating point at a predetermined resistance value as represented by a horizontal line in the figure tends to be delayed when the atmospheric humidity at the start is low; When it is high, it tends to be too early, and it has been found that this is mainly due to the fact that the time taken to reach the predetermined resistance value differs depending on the initial value due to the time-moisture absorption characteristics of the sensor 2. In consideration of the above conditions, in the present invention, the above-mentioned initial value AM initial value A2 or an arbitrary initial value A between them is stored in the control unit 5, and the resistance value of the sensor 2 is adjusted to a predetermined magnification. If the defroster drive section 6 is started to operate when the above-mentioned condition is reached, the optimum operation can be obtained without causing problems such as the above-mentioned time delay, that is, the magnification F=BI/A. ``B2/A2 = B, /A.'' We found that it is good to set it as ``B2/A2 = B, /A.'' As a result, the operating point B, = magnification F x initial value A, ...■ can be obtained, and in principle, The controller 5 may be configured to titrate Equation 0. However, as a result of further study by the inventor, the Equation 0 also has an exception term under extreme conditions, and specifically, the initial When the value A is very close to 100% humidity, it is impossible to change the magnification F after the fact, and therefore the operating point B2 of the characteristic line H shown in FIG.
% point, and set this point of 100% humidity as the lower limit value UP, and as shown by the characteristic line HH in the figure, the resistance value of the sensor 2 reaches the lower limit value UP. In some cases, the control section 5 operates the defroster drive section 6 regardless of the initial value, that is, without satisfying Equation 0. Similarly, when the humidity is low, such as in cold weather, even when the above equation 0 is satisfied, there are situations where the humidity is so low that no condensation occurs, and therefore condensation occurs at the condensation point B1 shown in Figure 2. The lower limit value DW is set to be the lower limit value DW.
When the value of the sensor 2 does not reach W, the defroster drive unit 6 is not operated even if the formula 0 is satisfied. Next, what is shown in FIG. 3 shows the operating principle of the control section 5 when transitioning from operation to stop.
As a result of studies conducted by the inventor, condensation occurs due to the interaction between the temperature of the glass surface and the humidity and air temperature inside the vehicle.In particular, in the case of automobiles, the temperature of the glass surface tends to rise as the defroster operates. In addition, the humidity and temperature inside the vehicle vary depending on the number of occupants, etc., and the resistance value of the sensor 2.4 when dew condensation is eliminated is not necessarily constant, but rather the control unit uses time as a factor. It has been found that it is preferable to calculate the stopping point using 5. To specifically explain the above using curves P1 to P4 shown in FIG. 3, curve P1 is for example when there is one occupant;
At this time, there are relatively few changes in the humidity and temperature inside the vehicle over time, so the defroster effect appears on the sensor 2 relatively quickly. Changes (increases) in the humidity and temperature in the vehicle interior become drastic, and as a result, the sensor 2 responds to the increase in humidity in the vehicle interior, and the sensor 2 follows a transition that appears to be upward but has no effect. Become. In fact, the above-mentioned increase in the humidity inside the vehicle reduces the effectiveness of the defroster and extends the time, but at the same time, as the time elapses after using the defroster becomes longer, the temperature of the glass surface also rises, causing the temperature inside the vehicle to increase. This increases the humidity which causes condensation. Therefore, it is most appropriate to change the stopping point depending on the coefficient of elapsed time. What was determined based on the above-mentioned facts is the stopping point shown as the step-like broken line R in Figure 3, and the dew condensation point B.
, and passes through the dew condensation point B again after passing through the dew condensation point B. From the elapsed time To to T, the initial value A is set as the stopping point. From time TI to T2 is (A, +α), from elapsed time T2 to T, is (A, +β), and from elapsed time T3 is (A, +γ) [However, α < β × γ, (
The stopping point is determined at (Ax+γ) <Bx). Here, we will specifically explain the stopping point on the rear glass 3. Although the stopping point may be determined by the same means as explained above, since the hot wire is laid directly on the surface of the rear glass 3, etc. Since the temperature of the glass surface rises rapidly and the anti-fogging effect is remarkable, and it is not affected by the increase or decrease in the number of occupants mentioned above, the rear defroster drive section 7 passes through the dew condensation point B again as shown in FIG. There is no practical problem even if the stopping point is a fixed time period T starting from the time point To. Since the control section 5 is required to perform complex operations as described above, it is preferable to use a microcomputer or the like when constructing an electric circuit embodying this operation.

【Effect of the invention】

As explained above, according to the present invention, the occurrence of dew condensation is calculated and operated using the initial value or limit value of each dew condensation sensor as a reference value, and the elimination of dew condensation is determined based on the elapsed time from the start of the operation and the By using a driving method that calculates and stops the dew condensation sensor value using the elapsed time as a coefficient, this is particularly noticeable in automobiles, such as changes in the number of occupants, changes in the state of the cabin due to air conditioning equipment, and seasonal changes. It can respond to any changes, such as changes in the US outside the vehicle due to other factors, without impairing visibility.
This has an excellent effect on improving safety and livability.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the auto defroster control method according to the present invention, FIG. 2 is a graph showing the principle of determining the operating point of the defroster in the same embodiment, and FIG.
This figure is a graph showing the principle of determining the stopping point for the windshield, and FIG. 4 is a graph showing the principle of determining the stopping point for the rear glass. 6...Front defroster drive unit 7...Rear defroster drive unit A1-A,...Initial value B, ~B,...Operating point

Claims (2)

[Claims] (1) A dew condensation sensor disposed on the windshield of an automobile, and a control unit that processes signals from the dew condensation sensor;
and a drive section that drives the defroster in response to a signal from the control section, and the control section calculates and sets an operating value using an initial value at power-on when the condensation sensor starts operating as a reference value. The humidity saturation value of the dew condensation sensor is set as an upper limit value, the output value of the dew condensation sensor corresponding to the lowest humidity required for generation of dew condensation on the window glass is held as a lower limit value, and the output from the dew condensation sensor is held as the lower limit value. A method for controlling an auto defroster, characterized in that when the value exceeds the operating value and reaches either the operating value or the upper limit value, an operating signal is issued to the drive section to drive the defroster. (2) A stop value is set as the elapsed time from the start of the operation of the defroster or the output value of the dew condensation sensor using the elapsed time as a coefficient for eliminating the condensation state, and the output value of the dew condensation sensor is set to the stop value. 2. The method of controlling an auto defroster according to claim 1, further comprising: issuing a stop signal to the drive unit to stop the defroster when the defroster reaches the predetermined limit.