JP2504620Y2 - Vehicle altimeter - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an altimeter for a vehicle, which is installed in, for example, an automobile and calculates and displays the present height (elevation) of the automobile based on atmospheric pressure.

[0002]

2. Description of the Related Art For example, as a conventional vehicle altimeter system for detecting the altitude of a driving point driving a mountainous area, as shown in FIG. The measurement is performed, the measurement signal is input to the calculation unit 2, the height of the point is calculated, and the altitude value at which the vehicle is positioned is displayed on the display unit 3 by the calculation signal.

[0003]

However, in such a conventional vehicle altimeter, the atmospheric pressure at the point where the automobile is located is measured, and the altitude at that point is calculated based on this atmospheric pressure. Is.

That is, altitude: H absolute temperature at 0 m above sea level: T ₀ pressure at measurement point: P at 0 m above sea level: P ₀ H = 153.85 × T ₀ × {1- (P / P ₀ ) ^0.190255 } ... (a) The altitude can be ^calculated by the following equation. Since the altitude value obtained by such a calculation formula is calculated based on the atmospheric pressure at the measurement point and the atmospheric pressure at 0 meters above sea level (sea level pressure), for example, if the atmospheric pressure changes due to weather changes, However, there is a problem that the altitude value changes even when the car is parked. That is, if a vehicle is stopped, the altitude at the stop point of the vehicle is constant, but if the atmospheric pressure decreases with the arrival of a typhoon, the altitude display value of the vehicle altimeter changes. However, there is a problem that the reliability of the display is low because an error occurs between the actual altitude value and the altitude display value displayed by the vehicle altimeter.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems. When a vehicle such as an automobile is stopped, the altitude indication value changes even if the atmospheric pressure fluctuates. Another object of the present invention is to provide a vehicle altimeter capable of increasing the accuracy and reliability of the indicated value without causing the fluctuation of

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in FIGS.

First, the structure of the vehicle altimeter according to the present embodiment will be described. Reference numeral 11 is a pressure detection unit for detecting atmospheric pressure, 12 is a vehicle speed detection unit for detecting a parked / stopped state of the vehicle,
13 is an input interface, 14 is the pressure detection unit 1
1 and an arithmetic unit for inputting the outputs from the vehicle speed detecting unit 12 through the input interface 13, 15 for inputting the output from the arithmetic unit 14 through the output interface 16, and a display unit for displaying the altitude value, 17 A storage unit connected to the arithmetic unit 14.

Next, the operation of this embodiment will be described with reference to the flow chart shown in FIG.

First, the flow when the vehicle (automobile) is parked and stopped will be described. The pressure detection unit 11 detects the atmospheric pressure value P 21, and the vehicle speed detection unit 12 further parks the vehicle. It is detected 22 whether the state, that is, the vehicle speed V = 0. Next, the first judgment step 23 detects whether the vehicle is parked or stopped (V = 0) in the parking / stop detection step 22, and if the vehicle is parked / stopped (V = 0) in the first judgment step 23. For example, the altitude value Z immediately before parking / stopping is stored in the atmospheric pressure storing step 24. When it is detected by the parking / stop detection step 22 that the vehicle is traveling, it is determined by the second determination step 25 whether or not the cycle after starting is the first cycle, and the first cycle after starting. If so, the reading step 26 reads the altitude value Z stored in the atmospheric pressure storing step 24, and the detecting step 27 detects the on-site atmospheric pressure P ₁ immediately after the vehicle starts, and then the sea level 0 m, that is, the sea level atmospheric pressure P.
_x is calculated in the calculation step 28, and a correction value is set.

This calculation formula is derived from the above formula (A): P _x = P _I /[-Z/(153.85×T ₀ ) +1] ^5.2561 (B) Next, in the altitude calculation step 29, the vehicle is positioned. The altitude H is calculated according to the equations (a) and (b): H = 153.85 × T ₀ × {1- (P / P _x ) ^0.190255 } ... (ha) ) The altitude at which the vehicle is located (elevation)
Is calculated, and this calculated value is output in the output step 30.

As for the flow when the vehicle is in a traveling state, the signal from the output step 30 is returned to the atmospheric pressure detection step 21, and thereafter, the parking / stop detection section step 22 and the first determination step 23 are stepped. At this time, in the second judgment step 25, since there is no stored value because it is the second cycle after starting, the altitude at which the vehicle is located is obtained from the above formula (c) by the altitude calculation step 29, and is output again at the output step 30. While the vehicle is running, this level is repeated.

As the flow when the vehicle is parked or stopped, the atmospheric pressure detection step 21 and the parked / parked state detection step 22 are stepped as described above, and in the parked / parked state detection step 22, the vehicle is parked (V = 0). So the first
In the judgment step 23, it is judged that the vehicle is parked. As a result, the vehicle position altitude immediately before parking / stopping is stored in the atmospheric pressure storing step 24, and the stored value at this time is Z
And

Therefore, according to this embodiment, the altitude at the vehicle position immediately before the vehicle is parked, that is, immediately before the vehicle is stopped is calculated, and the atmospheric pressure changes between the time the vehicle is parked and the vehicle is started again. Even if occurs, if the vehicle is parked or stopped, the altitude does not change, and if the vehicle starts again, the altitude at the time of starting is accurately displayed.

Further, in this embodiment, it is possible to predict the weather by displaying the atmospheric pressure value on the display unit.

[0015]

As described above, according to the present invention, the atmospheric pressure detecting section 11 for detecting the atmospheric pressure, and the current point altitude data are calculated based on the current point atmospheric pressure data and the sea level atmospheric pressure data from the atmospheric pressure detecting section 11. An arithmetic unit 14, a vehicle speed detection unit 12 that detects whether the vehicle is parked or stopped, and a storage unit 17 that stores current position altitude data immediately before the vehicle is parked or stopped, and the arithmetic unit 14 is provided immediately before the vehicle is parked or stopped. Based on the current position altitude data and the current position pressure data immediately after the vehicle starts, the sea level pressure data is calculated from the relational expression of the sea level pressure and the current position altitude and the current position pressure, and the sea level pressure data and the atmospheric pressure detection unit are also calculated. Since it is a vehicle altimeter that calculates the current position altitude data from the relational expression between the atmospheric pressure and the sea level pressure based on the current position atmospheric pressure data from 11, the vehicle stops or stops, that is, the vehicle stops. With height at said vehicle position immediately before is calculated, if the vehicle is in a state in which pressure variation is also parked occur until again starting from the parked,
The altitude does not change, and if the vehicle starts again, the effect that the altitude at the time of starting is accurately displayed is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a vehicle altimeter according to the present invention.

FIG. 2 is a flowchart for explaining the operation of this embodiment.

FIG. 3 is an explanatory block diagram of a conventional example.

[Explanation of symbols]

11: Pressure detection unit 12: Vehicle speed detection unit 13: Input interface 14: Calculation unit 15: Display unit 16: Output interface 17: Storage unit

Claims (1)

(57) [Scope of utility model registration request] 1. An atmospheric pressure detection unit (11) for detecting atmospheric pressure.
And a calculation unit (14) for calculating the current position altitude data based on the current position pressure data and the sea level pressure data from the pressure detection unit (11), and a vehicle speed detection unit (12) for detecting whether the vehicle is parked or stopped. And a storage unit (17) for storing altitude data of the current position of the vehicle immediately before parking and stopping, and the calculating unit (14) includes altitude data of the current position immediately before parking and stopping of the vehicle and the current position immediately after starting the vehicle. The sea level pressure data is calculated from the relational expression between the sea level pressure and the current position altitude and the current position pressure based on the barometric pressure data, and based on the sea level pressure data and the current position pressure data from the pressure detection unit (11). An altimeter for a vehicle, which calculates altitude data of the current location from a relational expression between atmospheric pressure and sea level pressure.