JPH03216579A - Ultrasonic speedometer - Google Patents

Abstract

PURPOSE:To achieve cost reduction, miniaturization and the enhancement of reliability by providing two pairs of ultrasonic transmitting and receiving terminals at a predetermined interval in a vehicle so that one pair are provided in reversed-opposed relation to an advance direction and the other pair are provided so as to be opposed in reverse relation thereto. CONSTITUTION:The transmitting terminal S1 and receiving terminal R1 of an ultrasonic transceiver are arranged on the line a-a' in a vehicle Q advancing in a D-direction at speed Va at an interval L and the transmitting terminal S2 and receiving terminal R2 of an ultrasonic transceiver are also arranged on the line b-b' in the vehicle Q in the reverse direction at the same interval. P1 shows the position of R1 when an ultrasonic signal reaches the receiving terminal R1 from the transmitting terminal S1 through a time t1 and P2 shows the position of R2 when the signal of the transmitting terminal S2 reaches the receiving terminal R2 through a time t2. When the advance speed of the vehicle Q is set to Va and the propagation speed of an ultrasonic wave in the vehicle Q is set to V(T), the relation of Va=(t2-t1)L/2t1t2 is formed and the times t1, t2 are measured to calculate Va by CPU. By this method, Va is obtained regardless of temp. and miniaturization, cost reduction and the enhancement of reliability can be achieved.

Description

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

The present invention relates to an ultrasonic speedometer that measures the speed of a vehicle or the like.

[Conventional technology]

Conventionally, many speedometers used to measure the speed of vehicles, etc., utilize rotating mechanisms, such as those found in vehicles.

[Problem to be solved by the invention]

When measuring traveling speed using a rotating mechanism, the durability of the rotating mechanism must be considered. Additionally, when processing the rotating mechanism to improve speed measurement, etc., the work is difficult. In the case of vehicles, speed is often measured using the number of rotations of the wheels, so errors in the diameter of the wheels can cause variations in speed, resulting in poor accuracy. Further, an ultrasonic speed meter using a pair of transmitter/receiver is troublesome because temperature changes inside the vehicle change the propagation speed of the ultrasonic signal. Therefore, it is an object of the present invention to measure the traveling speed of a vehicle without using a rotating mechanism. In the case of vehicles, the value determined by the speed of the vehicle should be directly determined, rather than being measured indirectly using the number of rotations of the wheels. Another object of the present invention is to provide a speedometer that does not require consideration of the temperature value even if the temperature inside the vehicle changes when measuring speed using ultrasonic waves.

[Means for Solving the Problems and Effects thereof] In order to achieve the above object, the present invention provides an ultrasonic signal transmitter and a receiver at a predetermined interval in a vehicle whose traveling speed is to be measured. Two pairs of vessel combinations are provided. One pair transmits ultrasonic waves from the transmitting end of the transmitter toward the receiving end of the receiver provided in the direction opposite to the traveling direction of the vehicle, and receives the ultrasonic waves at the receiving end. The other pair transmits an ultrasonic signal from the transmitting end of the transmitter to the receiving end of the receiver provided in the direction of travel of the vehicle at the same time or at the same time as the transmission of the ultrasonic signal. The ultrasonic signal transmission/reception system is configured so that it can receive f3 at In addition, a time measurement system using an electronic circuit or the like is configured to measure the time required for an ultrasonic signal to propagate between the two pairs of transmitting ends and receiving ends whose intervals are set in advance. Furthermore, by manually calculating the two pairs of transmitting/receiving distances and the propagation time of the ultrasonic signal, calculations using a computer circuit or the like can be used to calculate the vehicle's traveling speed in a manner that is not affected by temperature changes inside the vehicle. Configure the system. In addition, a speed output system such as a speed display device and a speed control panel used for automatic speed control is configured so that the measurer can perceive the information obtained by the above calculation. The object of the present invention is achieved by the above configuration and its operation.

【Example】

Although the subject matter of the present invention has been described with respect to a vehicle, it is not limited thereto. Embodiments of the present invention will be described below with reference to the attached drawings. Figure 1 is a simple block diagram showing an example of the configuration of the present invention. 1 is the ultrasonic signal transmission/reception (YX system) including the ultrasonic signal transmitting circuit, receiving circuit, power supply circuit, transmitting end S, receiving end R, etc. 2 is the transmitter whose name changes depending on the speed of the vehicle・A time measurement system that measures the propagation time of the ultrasonic signal between the receiving ends, 3 is a time measurement system that measures the propagation time of the ultrasonic signal between the two pairs of transmitting and receiving ends, and the vehicle progresses based on the distance between the two pairs of transmitting and receiving ends and the time that the ultrasonic signal propagates between them. A speed calculation system including a CPU that calculates the speed; 4 converts the value calculated in step 3 into a signal using a D-A converter or the like so that the measurer can perceive the vehicle's traveling speed or something equivalent thereto; Fig. 2 shows an example for explaining the measurement principle of the present invention, in which a vehicle Q traveling at a speed V in the D direction has a velocity output along the D direction. A combination of the transmitting end S of the ultrasonic transmitter and the receiving end R of the receiver is provided on the top, and the transmitting end S2 and receiving end R2 are similarly arranged at a distance of L from each other on b-b. P1 is the position of R1 when the ultrasonic wave fs transmitted from the sending end S reaches the receiving end after time t, and P2 is the position of f8 sent from the transmitting end S2. Let it represent the position of R2 when the signal reaches the receiving end after time t2.If the traveling speed of the vehicle is ■5 and the propagation speed of the ultrasonic signal inside the vehicle is V (T), then the following The relational expression holds: L=V (T)t, +v,t, ( 1
)V (T)t2=L+V,t2 (2
) (1) From equations (2), with the temperature parameter
By eliminating the propagation speed V (T) of the ultrasonic signal, the following equation is obtained. V,= (t2-t,)L/2t,t2 (3)
As is clear from equation (3), the vehicle's progress level, V, is calculated from the distance between the two pairs of transmitting and receiving ends and the propagation time of the ultrasonic signal, 1,,1. Figure 3 similarly shows two pairs of transmitting and receiving ends s/,, on the C-C' Keyaki along the direction of travel.
R'1, s/2, R'2, respectively at intervals L,, L
This is an example of placing it at 2. P゛, is the position where the iR signal transmitted from s+1 is received at t', or R', as in the previous example, and p+2 is the position where the signal transmitted from s + 2 is received at j2/mugi at R2. Indicates the position where the image will be pressed. In this case, the relational expressions are (4) and (5), and from this, (6)
is guided. L+ =V (T)t', +v,t,
(4)V(T)t2=L2+V,t,
(5) v, = (L.t'2-Lat, I/
2 t', t'2 (6) Fig. 4 shows an example in which the present invention is applied to an automobile, where S indicates the transmitting end and R indicates the receiving end. S and R are provided with directivity by a horn force bar N to avoid mutual interference of ultrasonic signals. The traveling speed of the vehicle is displayed on the front panel of storage case C, which compactly houses a system for measuring the propagation time of ultrasonic signals and calculating the traveling speed of the vehicle.

【Effect of the invention】

According to the present invention, an ultrasonic speed meter that does not use a rotating mechanism and is not affected by temperature changes inside the vehicle can be used, so speed measurement systems can be made lower in price, smaller in size, higher in quality, and more reliable. It will be possible to achieve this.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the present invention, Figures 2 and 3.
The figure explains the principle of an ultrasonic speed meter, and FIG. 4 is a schematic diagram of the present invention applied to an automobile. (A) is a plan view (opening) is a side view. Transmit/receive system Time measurement system Speed calculation system Speed output system − r−−=−−−−−−− −−→ Ne21 to 3rd 1,000 4M

Claims (1)

[Claims] In a speedometer installed inside a vehicle to measure the vehicle's traveling speed, one pair of ultrasonic signal transmitters and receivers facing each other at a predetermined interval is transmitted along the traveling direction of the vehicle. An ultrasonic signal transmitting/receiving system in which the transmitting end of the device is placed in the front, the receiving end of the receiver is placed in the rear, and the other pair is placed with the transmitting end in the rear and the receiving end in the front, and the ultrasonic signal is Using a time measurement system that measures the propagation time from the transmitting end to receiving it at the receiving end, the distance between the transmitting end and the receiving end of each of the two pairs of ultrasonic signals described above, and the propagation time described above. An ultrasonic speed meter comprising a speed calculation system that calculates the speed of a moving vehicle and a speed output system that outputs the calculation result.