JPH0447661Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an abnormality detection device for a speed detection circuit of a rotating body such as a dynamometer.

The rotating bodies used in dynamometers etc.
Usually, the rotational speed is controlled by a command from a speed control device so as to maintain a predetermined rotational speed. For this reason, the rotating body is provided with a rotational speed detection circuit. The schematic structure of this kind of rotational speed detection circuit is as shown in FIG. In FIG. 1, P and P are pulse pickups disposed in a non-contact or contact manner on a rotating body (not shown), and these pulse pickups P and P convert rotational speed into electrical signals. The pulse signals obtained by the pickups P and P are supplied to a frequency/voltage converter F/V, and a voltage proportional to the rotational speed is obtained at its output. This voltage is applied as a speed detection signal to a speed control device (not shown), and the speed of the rotating body is controlled by this signal.

In the rotational speed detection circuit shown in Fig. 1 above, the pulse pickups P, P and the frequency/voltage converter F/
If either one of V fails, the speed detection signal will
Ov, so no detection signal is input to the speed control device. Then, the speed of the rotating body could not be controlled, and the speed of the rotating body became abnormally high.
If this occurs, there is a risk that the rotating body may be destroyed. In order to prevent such accidents, a generator TG for rotation detection as shown in Figure 2 is installed on the rotating body, and the output of this generator TG is applied to the speed relay OSP. There is a means to detect speed. The failure rate of the method shown in FIG. 2 is the same as that of the method shown in FIG. 1, and there is no change in reliability.
In addition, in the case shown in Fig. 2, when the load is light and GD ² (moment of inertia) is small, the rate of increase in rotation after a failure occurs is large, and there is a delay time (about several tens of milliseconds) for protective operation. Therefore, there is a risk of destroying the rotating body. In addition, in FIG. 2, N is a tachometer.

This idea was made in view of the above circumstances, and it detects abnormalities in the speed detection circuit of a rotating body by providing two speed detection circuits and automatically switching to the other circuit when one circuit fails. The purpose is to provide equipment.

An embodiment of this invention will be described below with reference to the drawings.

In FIG. 3, P, P ₁ , P, P ₂ are first and second pulse pickups, and these first and second pulse pickups P, P ₁ , P, P ₂ are non-contact with a rotating body (not shown). It is arranged using the following means. The first and second pulse pickups P, P ₁ , P, P ₂
The output is obtained by converting the rotational speed into an electrical signal. These electrical signals have a first frequency, a second frequency,
It is supplied to voltage converters F/V ₁ and F/V ₂ to obtain output voltage signals S ₁ and S ₂ that are proportional to the rotational speed. The output terminals of the first and second frequency/voltage converters F/V ₁ and F/V ₂ are the switching contacts RY ₁ T which become the switching circuit of the relay RY ₁ described later, and the first and second fixed contacts T _a , T connected to _b . Note that a voltage signal S ₃ is sent to the movable contact T _c , and this signal S ₃ is supplied as a speed detection signal to a speed control device (not shown).

COP ₁ and COP ₂ are the first and second comparators that constitute the discriminator, and the outputs of both comparators COP ₁ and COP ₂ include the first and second comparators.
Second relays RY ₁ and RY ₂ are provided. These first and second relays RY ₁ and RY ₂ are operated as follows. That is, when the voltage signal S ₁ <S ₂ , the first
Relay RY ₁ is turned on, and when voltage signal S ₁ >S ₂ , second relay RY ₂ is turned on. Normally open contacts RY _1a and RY _2a of the first and second relays RY ₁ and RY ₂ are connected in parallel and input to an alarm device (not shown) that notifies a failure.

Next, the operation of the above embodiment will be described. Assume that the first pulse pickups P and _P1 are operating normally. At this time, the voltage signals S ₁ and S ₂ are S ₂ =S ₁ , and the signals of the first pulse pickups P and P ₁ are transferred from the first frequency/voltage converter F/V ₁ to the switching contact RY _1.
A speed detection signal is supplied to the speed control device via T. Here, the first pulse pickup P, P ₁
If either the frequency/voltage converter F/ _V1 or the first frequency/voltage converter F/V1 fails, the first comparator _COP1 determines that _S1 < _S2 and turns on the first relay _RY1 . By turning on, the movable contact T _c of the switching contact RY ₁ T is connected to the fixed contact T _b side which is different from that shown in the figure. As a result, the speed detection signal is supplied from the second pulse pickups P and _P2 , and the speed of the rotating body is controlled without abnormality. When the first relay RY ₁ is turned on, its normally open contact RY _1a is turned on and a failure alarm device (not shown) is activated, allowing confirmation and detection of failure.

On the other hand, the second pulse pickup P, P ₂
When either frequency/voltage converter F/V ₂ fails, the second comparator COP ₂ detects this and the second relay RY ₂ is turned on. As a result, the normally open contact RY _2a connected to the input of the failure alarm device is turned on and a failure alarm is issued. In this case, the rotating body is controlled by the output signals of the first pulse pickups P, _P1 . In the embodiment described above, when a failure is detected, the contacts are switched relatively quickly, so that the speed increase of the rotating body is extremely small. However, in the conventional example using a speed relay, the overspeed of the rotating body is detected when it reaches about 105 to 110%, so damage to the rotating body is not caused.

As described above, according to this invention, two circuits are provided to separately detect the rotational speed of the rotating body,
When one system fails, the system instantly switches to the other system and obtains a speed detection signal. This enables reliable detection of speed detection circuit failure and increases the speed of the rotating body without causing an overspeed condition. It has the advantage of being able to continue operating without any problems.

[Brief explanation of the drawing]

1 and 2 are schematic structural diagrams showing a conventional example, and FIG. 3 is a schematic structural diagram showing an embodiment of this invention. P, P ₁ , P, P ₂ ... 1st, 2nd pulse pickup, F/V ₁ , F/V ₂ ... 1st, 2nd frequency/voltage converter, COP ₁ , COP ₂ ... 1st , second comparator, RY ₁ , RY ₂ ... first and second relays.

Claims (1)

[Scope of utility model registration request] First and second speed electrical signal converters are separately provided on the rotating body and convert the rotational speed of the rotating body into electrical signals, and the output signals of these first and second converters are supplied separately to the output. first and second frequency/voltage converters that obtain voltage signals;
The voltage signal of the voltage converter is supplied separately to a first discriminator that determines abnormality from both voltage signals, and the voltage signal of the first frequency/voltage converter is normally sent as a speed detection signal, and the speed detection is performed. and a switching circuit that is switched in response to the determination signal when the first discriminator determines that the signal is an abnormality determination signal, and transmits a speed detection signal based on the voltage signal of the second frequency/voltage converter. An abnormality detection device for a speed detection circuit of a rotating body, characterized by: