JPH0225172Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The invention outputs the rotational speed of a rotating body, such as a propulsion shaft of a main marine engine, as a pulse with a frequency corresponding to the speed, and transmits the pulse to a control system. Regarding pulse transmission circuits, it is used in the actual rotational speed feedback system or actual rotational speed display system of marine main engine control devices.

(Prior art) Conventionally, this type of pulse transmission circuit was
There is a technique disclosed in Japanese Patent No. 38637, and this conventional technique is shown in FIG. 5 and explained below.

A first pulse generator 1 and a second pulse generator 2 are provided adjacent to a gear 51 fixed to a marine main engine propulsion shaft 50 as a rotating body. Both pulse generators 1 and 2 are composed of a pickup magnetically coupled to a gear 51, and output a first pulse 1P and a second pulse 2P having a phase difference of 90 degrees in accordance with the rotational speed of the propulsion shaft 50. do. The transmission circuit 52, which receives both pulses 1P and 2P, outputs a rotation direction signal to one output terminal 52a, and outputs the first pulse 1 to the other output terminal 52b.
P or the second pulse 2P is output. The signal from the output terminal 52a is sent to the AND gate 5
The pulse at the output end 52b is transmitted to one input end of each of the AND gates 56, 57 via the frequency divider circuits 53, 54 and the changeover switch 55.
is transmitted to the other input terminal of the . The output terminals of these AND gates 56 and 57 are connected to a drive circuit 58. The drive circuit 58 has a normal rotation input terminal 58a.
and a reverse rotation input terminal 58b, and based on the signals of these input terminals 58a and 58b, the motor 59 is
is rotated forward and reverse, and the pointer 60 is rotated forward and reverse.

That is, when the propulsion shaft 50 rotates normally, the output terminal 52a becomes high level, opens the AND gate 56, closes the AND gate 57, and closes the output terminal 5.
After the pulse 2b is frequency-divided, it is transmitted to the drive circuit 58 via the AND gate 56, and the motor 59 rotates in the normal direction, causing the pointer 60 to rotate in the normal direction. Further, when the propulsion shaft 50 is reversed, the output terminal 52a becomes a low level, closes the AND gate 56, and opens the AND gate 57, and the pulse at the output terminal 52b is frequency-divided and transmitted to the drive circuit 58, which drives the motor 59. is reversed and the pointer 60 is reversed. Note that the forward/reverse speed of the pointer 60 is the first pulse 1P or the second pulse 2P.
Since the speed corresponds to , the rotational speed of the propulsion shaft 50 can be roughly determined. Furthermore, the output terminal 52
The pulse b is taken out of the diagram and monitored by frequency-voltage conversion, and it is determined that the pulse is abnormal when the fuel rack (not shown) of the fuel pump is not 0 mm and the rotation speed is 0 rpm. There is.

(Problems with the prior art) However, the above conventional pulse transmission circuit has the following problems:
Since the pulse taken out to the output terminal 52b and transmitted to the subsequent stage is fixed to either the first pulse 1P or the second pulse 2P, for example, the first pulse 1P, the second pulse 2P is abnormal and the first pulse 1
If P is normal, a normal first pulse 1P can be transmitted to the subsequent stage but an abnormality in the second pulse generator 2 cannot be detected, or if the second pulse 2P is normal but an abnormality occurs in the first pulse 1P Although it is possible to detect an abnormality in the first pulse generator 1, there is a problem in that it interferes with the control that allows the normal second pulse 2P to be transmitted to the subsequent control system.

(Technical Problem of the Invention) Therefore, the present invention includes first and second pulse generators that each output pulses with a frequency corresponding to the rotational speed of one rotating body, and the pulses from one of the pulse generators are A technology that monitors the first and second pulses in a pulse transmission circuit to distinguish between normal and abnormal pulses, and selects and transmits the normal pulse. (Technical Means of the Invention) The technical means of the present invention to solve this technical problem is that, in the pulse transmission circuit, first and second pulses are configured to detect the edge of each pulse from the pulse generator. 2 edge detection circuit, first and second frequency dividing circuits that frequency divide each pulse from both of the pulse generators by 1/n (where n is an integer of 1 or more), and the second frequency dividing circuit. a first edge discriminating circuit for discriminating the presence or absence of a first edge signal from a first edge detecting circuit in one period of a second frequency-divided pulse; A first latch circuit that latches based on a frequency division pulse, and a second edge determination circuit that determines the presence or absence of a second edge signal from a second edge detection circuit during one cycle of the first frequency division pulse from the first frequency division circuit. a second latch circuit that latches a second discrimination signal from a second edge discrimination circuit with the first frequency-divided pulse; and a discrimination circuit that discriminates a normal pulse generator based on the latch outputs from both of these latch circuits. and a switching circuit that selects a pulse from one of the pulse generators when both pulse generators are normal, and selects a normal pulse from the other when one of the pulse generators is abnormal, based on the discrimination signal from the discrimination circuit. It is.

(Operation) According to the technical means of the present invention, both edge detection circuits detect the edges of each pulse, and both frequency dividing circuits divide each pulse into 1/n,
Both edge discrimination circuits each discriminate whether or not the other pulse edge exists during one cycle of one frequency-divided pulse, and both latch circuits each latch one discrimination signal in synchronization with the other frequency-divided pulse. Then, the discrimination circuit compares the outputs of both latches to discriminate whether both pulse generators are normal or abnormal, and the switching circuit transmits the pulse from the normal pulse generator to the next one based on the discrimination signal.

(Effect of the invention) Therefore, according to the invention having the above-mentioned technical means, one pulse is frequency-divided, and the edge of the other pulse is set as a reference during one cycle of the divided pulse that is the reference. Since both pulses mutually monitor whether or not they exist, it is possible to detect which of the two pulses is abnormal.
Since the pulse and the second pulse are switched, the normal pulse can always be transmitted.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4. Furthermore, Figure 1 is a block diagram.
2 to 4 are operation time charts.

First, Fig. 1 and 2 show the case where there is no abnormality in both pulse generators 1 and 2 and both pulses 1P and 2P are normal.
This will be explained using figures.

The first and second pulse generators 1 and 2 are rotating bodies (fifth
First and second pulses 1P and 2P having a phase difference of 90 degrees are output at a frequency corresponding to the rotation speed of the motor (see figure). The first and second edge detection circuits 11 and 21 detect edges on both sides of the first and second pulses 1P and 2P and output first and second edge signals 11P and 21P. The first and second frequency dividing circuits 12 and 22 are
Pulses 1P and 2P are frequency-divided by 1/4 to output first and second frequency-divided pulses 12P and 22P.

The first edge discrimination circuit 13 uses the fifth frequency divided pulse 2
Since there is no first edge signal 11P at the rise of 2P, the first discrimination signal 13P is abnormal (low level)
When the first edge signal 11P is detected, the first discrimination signal 13P is set to normal (high level) and maintained normal until the next rise of the second divided pulse 22P. Divide-by-2 pulse 2
Repeat every time 2P rises. First latch circuit 1
4 latches the first discrimination signal 13P just before the second frequency-divided pulse 22P rises, so that the first latch output 14P is always normal (high level).

Similarly, the second edge discrimination circuit 23 detects the second edge signal 21P at the rising edge of the first frequency-divided pulse 12P.
Therefore, the second discrimination signal 23P is set to abnormal (low level), and when the second edge signal 21P is detected, the second discrimination signal 23P is set to normal (high level), and the first edge signal 23P is set to normal (high level). Peripheral pulse 12P
The normal state is maintained until the next rising edge of , and this is repeated every rising edge of the first frequency-divided pulse 12P. The second latch circuit 24 latches the second discrimination signal 23P just before the first frequency-divided pulse 12P rises, so that the second latch output 24P is always maintained at a normal level (high level).

Then, the discrimination circuit 30 discriminates that both pulses 1P and 2P are normal, and the discrimination signal 30
Let P be a low level for selecting one of the pulses, for example the first pulse 1P. This low level discrimination signal 30P
Accordingly, the switching circuit 31 selects and outputs the first pulse 1P, and transmits it to the frequency-voltage converter 40.

Next, regarding the case where there is no abnormality in the first pulse generator 1 and the first pulse 1P is normal, but an abnormality occurs in the second pulse generator 2 and the second pulse 2P becomes abnormal (for example, held at a low level). , will be explained based on FIGS. 1 and 3.

In this case, since the first pulse 1P is normal,
First edge signal 11P and first frequency divided pulse 12
P is the same as in FIG.

In FIG. 3, when the second pulse 2P goes to a low level at time t1 and continues to remain at a low level thereafter, the second edge signal 21P disappears and the second frequency-divided pulse 22P also does not exist thereafter.

Therefore, since the second frequency divided pulse 22P does not rise after t1, the first edge signal 13P of the first edge discrimination circuit 13 is held at the previous normal high level, and the first edge signal 13P of the first latch circuit 14 The latch output 14P is also held at its previously normal high level.

On the other hand, in the second edge discrimination circuit 23, since the second edge signal 21P already does not exist at the time t2 of the first rise of the first frequency divided pulse 12P after t1, the second edge discrimination signal 23P is abnormally (low level) ), and the subsequent first frequency divided pulse 12
Since there is no second edge signal 21P even when P rises, the second discrimination signal 23P is held abnormally (low level) after t2. Therefore, the second latch circuit 24 latches the immediately preceding second discrimination signal 23P at the rise of the first frequency-divided pulse 12P at time t2, and holds the second latch output 24P at normal (high level). , first frequency divided pulse 1 after t2
At the first rise of 2P, at t3, the immediately previous second discrimination signal 23P is latched, so the second latch output 24P is changed to abnormal (low level).

Then, the discrimination circuit 30 discriminates between the abnormality of the second pulse 2P and the normality of the first pulse 1P at time t3, and holds the discrimination signal 30P at a low level for selecting the first pulse 1P. Therefore, the switching circuit 31 selectively outputs the first pulse 1P based on the low-level discrimination signal 30P and transmits it to the frequency-voltage converter 40.

Conversely, if there is no abnormality in the second pulse generator 2 and the second pulse 2P is normal, but an abnormality occurs in the first pulse generator 1 and the first pulse 1P becomes abnormal (for example, held at a high level). The case will be explained below based on FIGS. 1 and 4.

In this case, since the second pulse 2P is normal,
Second edge signal 21P and second frequency divided pulse 22
P is the same as in FIG.

In FIG. 4, when the first pulse 1P becomes high level at time t5 and continues to be at a high level thereafter, the first edge signal 11P disappears after that, and the first frequency-divided pulse 12P also disappears thereafter.

Therefore, the first edge discrimination circuit 13
Since there is already no first edge signal 11P at the first rise after t5 of the divided pulse 22P, the first edge signal 11P
Change the discrimination signal 13P to abnormal (low level),
Since the first edge signal 11P is not present at the subsequent rise of the second frequency-divided pulse 22P, the first discrimination signal 13P is held at an abnormal level (low level). For this reason, the first latch circuit 14 latches the immediately preceding first discrimination signal 13P at the first rise of the second frequency-divided pulse 22P after t5, and outputs the first latch output 1.
4P is maintained at normal (high level), but at time t5
At the second rise time t6 of the second frequency-divided pulse 22P, the previous first discrimination signal 13P is latched, so the first latch output 14P is changed to abnormal (low level).

On the other hand, in the second edge discrimination circuit 23, since there is no second edge signal 21P at the rise of the first frequency-divided pulse 12P at time t5, the second discrimination signal 23P is determined to be abnormal (low level). The second discrimination signal 23 is determined by the second edge signal 21P of
P is returned to normal (high level), and since there is no rise of the first divided pulse 12P, the second
The discrimination signal 23P is kept normal (high level).
The second latch circuit 24 maintains the second latch output 24P at a normal level (high level) since the first frequency-divided pulse 12P does not rise after time t5.

Therefore, the discrimination circuit 30 discriminates whether the first pulse 1P is abnormal or the second pulse 2P is normal at time t6, and converts the discrimination signal 30P to a high level for selecting the second pulse 2P. Therefore, the switching circuit 31 selectively outputs the second pulse 2P based on the high level discrimination signal 30P at time t6 and transmits it to the frequency-voltage converter 40.

In the above embodiment, both frequency dividing circuits 1
The frequency division ratio of 2 and 22 was set to 1/4, but this is 1/1, 1/2,
It can be set appropriately to 1/3, 1/5, etc., and is generally expressed as 1/n. However, n is an integer greater than or equal to 1, and the smaller n is, the higher the abnormality detection accuracy is.

Further, in the above embodiment, the double edge detection circuits 11 and 21 are of a double edge detection type, but may be of a single edge detection type that detects only either the rising edge or the falling edge of a pulse.

Furthermore, in the above embodiment, both pulses 1
It is assumed that P and 2P have a phase difference of 90 degrees, but
This is because the rotation direction is generally determined at the same time as the rotation speed is detected, and phase difference is often used as a means for determining the rotation direction. It can also be applied when there is no phase difference.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the pulse transmission circuit of the present invention, FIGS. 2 to 4 are time charts showing the operation of the same embodiment, and FIG. 5 is a conventional technique. 50... Rotating body, 1... First pulse generator, 2
...Second pulse generator, 11...First edge detection circuit, 21...Second edge detection circuit, 12...First frequency division circuit, 22...Second frequency division circuit, 13...First edge detection circuit Discrimination circuit, 23...second edge discrimination circuit, 14...first latch circuit, 24...second latch circuit, 30...discrimination circuit, 31...switching circuit.

Claims (1)

[Claims for Utility Model Registration] (1) A first and second pulse generator each outputting pulses with a frequency corresponding to the rotational speed of one rotating body, and transmitting the pulses from one of the pulse generators. In the pulse transmission circuit, first and second edge detection circuits detect edges of respective pulses from both the pulse generators, and 1/n (where n is 1) each pulse from both the pulse generators. (integer greater than or equal to)
first and second frequency dividing circuits that divide the frequency into
a first edge determination circuit that determines the presence or absence of a first edge signal from the first edge detection circuit in one cycle of the second frequency-divided pulse from the frequency division circuit;
The first discrimination signal from the edge discrimination circuit is
A first latch circuit that latches according to a frequency division pulse, and a second edge detection circuit that latches a second edge from a second edge detection circuit during one period of the first frequency division pulse from the first frequency division circuit.
a second edge discriminating circuit for discriminating the presence or absence of an edge signal; and a second edge discriminating circuit for latching a second discriminating signal from the second edge discriminating circuit using the first frequency-divided pulse.
a latch circuit, a discrimination circuit for discriminating a normal pulse generator based on the latch outputs from both latch circuits, and a pulse from either pulse generator when both pulse generators are normal based on a discrimination signal from the discrimination circuit; a switching circuit that selects a normal pulse from the other when one is abnormal;
A pulse transmission circuit comprising: (2) The pulse transmission circuit according to claim 1, in which the rotating body is a marine main engine propulsion shaft.