JPS62103522A - Mass flowmeter and signal processing system thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates generally to the measurement of mass flow rates of fluids, and more particularly to signal processing systems for mass flow meters and mass flow meters using the signal processing systems. It pertains to.

BACKGROUND OF THE INVENTION It is often necessary to very accurately measure the flow rate of prior art materials as they flow through a supply line. for example,
The actual amount of material sent to the material buyer is measured by a meter that measures the amount or mass of material flowing from the seller's material storage to the buyer's container. If the meter that measures the amount or mass of material sent to the buyer is inaccurate, the buyer or seller will suffer. In addition, the mass flow rate of materials produced for human consumption can be measured at 4Ig by meters placed in the conduits supplying the materials, such that there are no obstacles in the material flow path that could contaminate the materials. It is most desirable that the

One type of mass flow meter that meets the above requirements uses a movable conduit placed in the line supplying the fluid whose mass flow rate is to be measured.

Often referred to as a "vibration" meter or a "Coriolis force" meter. As the fluid moves within the conduit, the conduit itself vibrates, exerting forces on the conduit causing it to deform. The magnitude of these forces, one of which is the Coriolis force, is related to the mass flow rate of the fluid within the conduit. Therefore, either by determining the magnitude of this force or by measuring the properties of the conduit, i.e. its movement, that are affected by this force.

The mass flow rate of the fluid can be measured. The following US patents disclose vibratory mass flow meters using various shapes of conduits and various types of signal processing systems: US Pat.

U.S. Patent No. 3,485,098; U.S. Patent No. 4.10
No. 9.524; U.S. Pat. No. 4,127,028; U.S. Pat. No. 4,192,184; U.S. Pat. ．． 252
,028; U.S. Patent No. 4,311.054; U.S. Patent Reissue No. 31,450; U.S. Patent No. 4.422,3
No. 38; US Pat. No. 4,444,059; and US Pat. No. 4,491,025.

Each meter disclosed in the above patents uses a sensor that generates electrical signals related to movement of the conduit at two points. The above two points are chosen such that there is a phase and time difference between the two signals, and this phase and time difference is .

Ideally, it should be zero when the mass flow rate of the fluid is zero,
The flow rate difference changes from a state of zero to a state related to the mass flow rate of the fluid. In general, the movement of the conduit at three selected points when the meter is under no flow conditions can be expressed as:

Z (A) = ZA sin (vt)
(1) Z (D) = ZOsin (wt)
(2) Z(B) = ZB sin (wt)
(3) However, A and B indicate the two sensing points of the conduit where the movement sensors are placed, D indicates the driving point of the conduit where a driving force is applied to the conduit and vibrates the conduit, and Z (A ) and Z(B
)teeth.

Denotes the displacement or position of two points A and B at time t, Z(D) is the position or displacement of the conduit at the driving point, and ZA, ZD and ZB are the resting states of points A, D and B. represents the maximum displacement from .

t is 1 hour (seconds) and W is the frequency of the driving force (7 radians).

When fluid flows through the conduit, the above equation (1), (
2) and (3) become linear.

Z (A) = ZA sin [wt+f(M)]
(4) Z (D) = ZD sin [wt]
(5) Z(B) = ZB sin
[wt-f(M)] (6) However, f(M)
is a mathematical expression that expresses the difference between two phase angles in terms of mass flow rate.

Known meters often use position sensors to convert the movement of the vibrating conduit at points A and B into electrical signals, which can be expressed as:

Vl = VPA sin Cvt + f (M)]
(7) V2=VPB sin [wt
-f (M)] (8) However,
Vl and vl represent the voltages corresponding to the movement of the vibrating conduit, and VPA and VPB are the peak voltages of the electrical signal corresponding to the maximum displacement of the conduit at points A and B. A graph representing Vl and vl is shown in FIG. Note that velocity or acceleration sensors are often used to detect conduit movement.

The velocity and acceleration sensors generate signals represented by the appropriate derivatives with respect to time of equations (7) and (8) above.

Therefore, mass flow rate information is included as phase information in each variable of equations (7) and (8). The magnitude of the peak voltage of the speed and acceleration sensor is based on the frequency of the driving force.

Known vibratory mass flowmeters generally use either differential amplification techniques or time difference techniques to satisfy equations (7) and (
8) Derive mass flow rate information from

When using differential amplification techniques, voltages v1 and vl are sent to a differential amplifier, which determines the difference between vl and vl as follows.

Vl-V2=VPA sin[vt+f(M)]
VPB sin[vt-f (M)] (9) By using appropriate trigonometry, equation (9) becomes:

Vl-V2=(VPA-VPB) [cosf (M)]
sin wt+(VPA+VPB) [sin f (
M) ] cos wt (10) By adjusting the gain associated with each position sensor to set VPA equal to VPB, the maximum value of the formula % f (M) above is small, about 2 degrees or less. If , then ginf (M) is equal to W f (M), and there are a number of drawbacks when using differential amplification techniques.

First, since the output of the differential amplifier is in analog form,
Problems arise when interfacing with digital devices. Second, a vibratory mass flow meter using differential amplification technology
Values of l) greater than about 3 degrees introduce at least some inaccuracy to equation (12). Furthermore, the value of the difference between vl and 2, and thus the calculated mass flow rate, will be based on the vibration amplitude of the vibrating conduit and the gain constant of the position sensor.

When using the time difference technique, a pair of voltage comparators A and B of the type shown in FIG. 19 are used. Comparator A is
Its non-inverting terminal receives the input voltage ■1, and its inverting terminal receives the threshold voltage VT^. Comparator B receives the input voltage v2 at its non-inverting terminal and the threshold voltage VTA at its inverting terminal.

Each comparator generates a high level signal when the input voltage exceeds a threshold voltage and generates a low level signal when the threshold voltage is higher than the input voltage. The electric signals v1 and v2 generated by the movement sensor and the threshold voltages VTA and VTB are the 20th
This is shown in Figure (a). Also shown in FIG. 20(b) are signals Cx and Cy generated by comparators A and B. In the time difference technique, the time difference between the occurrence of a pair of signal edges for each cycle of Cx and cy is measured, as shown in FIG. 20(b). When using the time difference technique, the above equations (7) and (8) become as follows.

V1=VTA=VPA sin[w(TA)+f
(M)ko (13)
V2=VTB=VPB sin[w(TB)+f (
M) (14) However, TA represents the time when ■1 is equal to VTA, and TB number -t, V2 represents the time equal to VTB.

Solving for TA and TB results in the following.

TA= [(arcsin VTA/VPA)/w −
f (M)/w (15) TB= [(a
rcsin VTB/VPB)/w -f (M)/w
(16) Taking the difference between TA and TO gives the following.

TB-TA= 2 f (M)/w+[(arcsin
VTB/VPB-(arcsin VTA/VPA)
co/w (17) This equation (17) is expressed as the time difference (
TB-TA) is directly proportional to the 1-hour term f(M)/w and the constant divided by the frequency W. The time difference term (TB-TA) is most commonly converted to a corresponding voltage by analog/digital approximation techniques.

A major drawback associated with the use of time difference techniques is that the time difference depends on the frequency W of the conduit. The frequency changes due to changes in the density of the fluid flowing through the conduit and changes in the properties of the conduit due to temperature.

SUMMARY OF THE INVENTION Accordingly, there is a need for a mass flow meter that utilizes the Coriolis force and is independent of conduit frequency or motion amplitude to measure fluid mass flow. Additionally, there is a need for a mass flow meter that produces a digital output that can be commonly used by digital computer equipment.

SUMMARY OF THE INVENTION The present invention provides a system for indicating the phase difference that exists between two periodic electrical signals. The system includes apparatus for generating a measurement comparison signal from a first of the periodic electrical signals and a measurement threshold signal, the measurement comparison signal and the first periodic electrical signal is based on the level of the measurement threshold signal relative to the first periodic signal. or,
Apparatus is provided for generating a measured characteristic signal related to the peak amplitude of the first periodic signal.

Also included is an apparatus for generating a command signal, the nature of which is based on whether the measured comparison signal leads or lags the reference signal. A device is also provided for accumulating a count signal, the command signal determining when the level of this count signal increases and when it decreases. A device is also provided for combining a signal corresponding to the count signal and the measurement characteristic signal to generate a measurement threshold signal. The reference signal is
Preferably, it is a second signal of the periodic electrical signals, ie a signal having a constant phase. However, more preferably the reference signal is derived from said second periodic signal, in which case said generator further comprises a reference comparison signal from said second periodic electrical signal and a reference threshold. A hold signal is generated. The phase difference between the reference comparison signal and the second periodic signal is based on the level of the reference threshold signal relative to the second periodic signal. The generating means further generates a reference characteristic signal related to the peak amplitude of the second periodic signal. The nature of the command signal generated by the command signal generator is based on whether the measured comparison signal leads or lags the reference comparison signal.The synthesizer combines the reference characteristic signal and the signal derived from the count signal. to generate a reference threshold signal.

The invention further includes a conduit attached at both ends to a support, a device for vibrating the conduit, and a device for generating a pair of periodic electrical signals representative of the motion characteristics of the conduit at two predetermined points. A mass flow meter is provided. The flow meter includes a system that indicates the phase difference that exists between two periodic electrical signals. The system includes apparatus for generating a measurement comparison signal from a first of the periodic electrical signals and a measurement threshold signal. The phase difference between the measurement comparison signal and the first periodic signal is based on the level of the measurement threshold signal with respect to the first periodic signal. The system includes a device for generating a measured characteristic signal.

This measured characteristic signal is related to the peak amplitude of the first periodic signal. A device is also provided for generating a command signal, the nature of which is based on whether the measured comparison signal leads or lags the reference signal. In this case too.

The reference signal can be in any of a number of formats.

Apparatus is also provided for accumulating the count signal, and the command signal determines when the level of the count signal increases and when it decreases. A device is also provided for combining a signal corresponding to the count signal and a measurement characteristic signal to generate a measurement threshold signal.

Furthermore, the present invention provides a mass flow meter having a conduit attached at one end to a support and a device for vibrating the conduit. A device is provided for generating a pair of periodic electrical signals representative of the motion characteristics of the conduit at two predetermined points. The flow meter includes a system for indicating the phase difference between the two periodic electrical signals.

The system includes apparatus for receiving the periodic signals and generating a comparison signal from at least a first of the periodic electrical signals. A device for shifting the comparison signal so as to reduce the phase difference between the comparison signal and the reference signal to a predetermined magnitude is also provided. A device is also provided for monitoring and accumulating angles. This accumulated angle therefore indicates the phase difference between the periodic electrical signals when the phase difference between the comparison signal and the reference signal reaches a predetermined magnitude.

Preferably, the flowmeter is capable of compensating for mechanical and electrical noise occurring at zero flow rate to eliminate deviations occurring in the flowmeter. It is also preferred to perform the compensation using a two-step procedure.

In this case, first a rough adjustment of the system is performed.

Then, its fine-tuning is performed.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

TECHNICAL FIELD This invention relates to flow meters that measure mass flow rates of fluids, and signal processing systems particularly useful for such mass flow meters. Preferred mass flow meters generally include a sensing assembly that generates a pair of electrical signals containing mass flow information and a signal processing system that extracts the mass flow information from the signals generated by the sensing assembly.

1-8 illustrate a preferred flow meter sensing assembly IO of the present invention. This sensing assembly 10 includes 19
U.S. Patent Application No. 655, filed on September 26, 1984.
It is of the type disclosed in No. 305. However, a sensing assembly having a suitable conduit of known shape may be used in the system according to the invention. Sensing assembly 10 includes a conduit 12 defining conduit portions 18 and 20. Conduit portion 18 defines an inlet 14 and an outlet 16. Conduit section 20 defines an inlet 33 and an outlet 35. The central body 11 defines a manifold portion 22 that includes flow passages 61
provides fluid communication between inlets 14 and 33 and a supply line (not shown). Outlet manifold part 2
4 joins and provides fluid communication between the supply conduit and the outlets 16 and 35 by a flow path 51. Macholt 22 defines an inlet 13 that can be placed in fluid communication with a supply line using a circular flange 15 and an outlet 25 that allows fluid to reach conduit 12 . Manifold 24 defines an inlet 49 for receiving fluid from conduit 12 and an outlet 17 that can be placed in fluid communication with the supply line using circular flange 19. Flanges 15 and 19 are
Each channel 21 and 23 receives fluid from the supply line and bolts (not shown) securing the supply line to the conduit 12
Defining each bolt hole 57 and 59 for receiving a. The flow path 61 of the manifold 22 is connected from the supply line to the manifold 22.
It is circular at the inlet 13 to facilitate the flow of fluid into the inlet. Channel 61 is oblong at outlet 25 of manifold 22 to facilitate splitting the fluid into two streams. Each split stream flows into conduit section 18 or 20. A one-piece oblong inlet casing 27 is sized to mate with the outlet 25 of the manifold 22. The casing 27 is.

It defines two channels 29 and 31, each of which has a population of 1
4 or 33. Casing 27 is welded to outlet 25 of manifold 22 and inlets 14 and 33 of conduit sections 18 and 20. Therefore, casing 2
7 splits the fluid flowing to outlet 25 into two streams and guides these streams into conduit sections 18 and 20.

The flow passages 51 of the manifold 24 have a circular cross section at the outlet 17 to facilitate fluid flow between the outlet 17 and the supply line. Further, the flow path 51 is connected to the conduit portion 18
and has an oval cross section at the inlet 49 to facilitate fluid flow between the inlet 20 and the inlet 49. The oval outlet casing 53 defines a pair of openings 63 and 65 that are connected to the outlet 16 of the conduit sections 18 and 20.
and 35 respectively. Oval insulation 37 defines a passageway 39 for receiving conduit section 18 and a passageway 41 for receiving conduit section 20 . Oval insulation 43 defines a pair of passageways 45 and 47 that receive outlets 16 and 35 of conduit sections 18 and 20. Insulators 37 and 43 are connected to conduit sections 18 and 20.
The vibrations of the insulators 37 and 43 are limited to the area between the insulators 37 and 43.

Walls 58 and 60 of body 11 have rectangular openings 62 and 6
4, which receive conduit sections 18 and 2o to facilitate assembly of assembly 10. A pair of housings 66 and 68 (shown in phantom in FIGS. 1 and 8) may be secured to channels 70, 72, 74 and 76 to form a cover for central body 11.

Sensing assembly 10 is installed in a supply line supplying a fluid whose mass flow rate is to be measured. This conduit.

broken to form a fluid outlet and fluid re-entrance.

The inlet 13 of the sensing assembly 10 is placed in fluid communication with the outlet of the conduit using a flange 15, and the outlet 17 is
The flange 19 is placed in fluid communication with the re-entrance of the conduit. Accordingly, fluid flowing into the conduit exits the outlet of the 5 conduit and enters the sensing assembly at the inlet 13. After passing through the flow passages 61 of the manifold 22, the fluid is split by the casing 27 into two streams of generally the same mass flow rate. These two flows are connected to section 18 of the conduit.
and 20 and flows. These flows flow into the casing 5
3 and after entering manifold 24.

The two streams merge. The combined flow passes through channel 61, exits the sensing assembly outlet 17, and reenters the conduit.

Sensor assembly 10 includes a conduit drive assembly 26 and a pair of speed sensors 28 and 30. Instead of speed sensors 28 and 30, position or acceleration sensors or other types of motion sensors can also be used. Conduit drive assembly 26 applies force to conduit sections 18 and 20 along axis z-z'. The direction in which assembly 26 applies a force to portions 18 and 20 is
It can be periodically reversed to oscillate 0.

The direction in which assembly 26 applies a force to portion 18 is determined by assembly 26
is always opposite to the direction in which force is applied to portion 20.

As shown in FIG. 7, each sensor 28 and 30 and conduit drive assembly 26 includes a cylindrical permanent magnet 48 secured to a magnet holder 50. As shown in FIG. This permanent magnet 48 is connected to a passage 52 formed by a cylindrical electric coil 54.
accepted.

Magnet holder 50 is secured to section 20 and coil 54 is secured to conduit section 18 in any suitable manner. Thus, as conduit sections 18 and 20 move relative to each other, magnet 48 is moved within passageway 52 of sensors 28 and 30.

Movement of magnet 48 within coil 54 of speed sensor 28 or 30 produces a voltage (of the type shown in FIGS. 10 and 18) that is proportional to the speed at which conduit sections 18 and 20 move relative to each other. The conduit drive assembly 26 also includes a permanent magnet 48 secured to a magnet holder 50 and an electrical coil 54 defining a passageway 52. The magnet holder 50 of the assembly 26 is secured to the conduit portion 20; coil 5
4 is fixed to part 18 of the conduit. When a sinusoidal voltage is applied to coil 54 of assembly 26, coil 54 and holder 50 vibrate relative to each other, causing conduit sections 18 and 20 to vibrate. Accordingly, conduit drive assembly 26
Applying a sinusoidal voltage to coil 54 causes conduit sections 18 and 20 to vibrate and causes sensors 28 and 3 to vibrate.
0 generate a sinusoidal voltage signal that is proportional to the speed at which the section of conduit to which they are attached moves.

When the mass flow rate of fluid flowing through sections 18 and 20 is zero, the sinusoidal signals produced by velocity sensors 28 and 30 are ideally in phase with each other. However,
Fluid flowing into conduit sections 18 and 20 interacts with the vibrating conduit sections 18 and 20, creating a Coriolis force acting on conduit sections 18 and 20.

The generation of Coriolis forces in a vibrating conduit and the effect of these forces on the movement of the conduit are discussed in detail in the prior art description above. When Coriolis forces occur, the vibrating portions 18 and 20 of the conduit are moved out of phase with each other. Therefore.

When fluid flows through conduit 12 and conduit drive assembly 26 vibrates sections 18 and 20 of the conduit, velocity sensors 28 and 30 generate signals in mutually out-of-phase form, shown as vl and v2 in FIG. occurs. The magnitude of this phase shift is related to the magnitude of the Coriolis force generated by the vibrating conduit and, in turn, the magnitude of the mass flow rate flowing through the conduit 12.

Preferred signal processing system 1 provided by the present invention
00 is shown in FIG. This system 100 is
A sinusoidal signal generated by speed sensors 28 and 30 is received. System 100 directly indicates the amount of phase shift that exists between two signals. Once the magnitude of the phase shift is known, the relationship between phase shift and mass flow rate (which depends on the characteristics of the sensor assembly used and the properties of the fluid whose mass flow rate is to be measured) can be used to determine the mass flow rate. can do. The technique used by signal processing system 1oO allows the phase shift to be determined essentially without regard to the peak amplitude or angular frequency of the sinusoidal force applied by conduit drive assembly 26 to conduit sections 18 and 20. . Therefore, the many factors that affect the amplitude and frequency of conduit vibrations do not significantly affect the phase shift measurements made by system 100.

Rather than taking the difference between equations (15) and (16) (this is
system 1).
00 effectively makes equation (15) equal to equation (16). This equalization involves generating comparison signals that correspond to the electrical signals generated by sensors 28 and 30 and shifting one of the comparison signals toward the other signal to essentially create a position between the two comparison signals. It is obtained by ensuring that no phase difference exists and recording the amount of shift required to eliminate the phase difference. Equating equations (15) and (16) yields the following.

[arcsin (VTR/VPB) + f (M)]
/w=[arcsin (VTA/VPA)-f (M
)]/w (18) Solving this for 2f(M) yields the following.

2 f (M) = arcsin (VTA/VPA) - a
rcsin(VTB/VPB) (1
9) System 100 uses VTA as a constant determined at zero flow rate in conduit 12.

The solution for VTB is as follows.

VTB=VPB sin [5rcsin(VTA/V
PA)−2f (M)] (20) Therefore, the DC voltage VTB is determined by the phase difference sj,n 2 f (M ) is proportional to The technique used in system 100 provides highly accurate results if the following conditions are met:

=90° < [arcsin(VTA/VPA)-
2f (M)ko <+90'' (21) Another solution is to generate only one comparison signal from one of the signals generated by sensors 28 or 30 and to transfer this comparison signal to (i) the other sensor 28 or 3o or (ii) a reference signal having a constant phase to bring the phase difference to zero.The magnitude of this phase shift represents the phase difference.

Using equation (2o) in system 100, conduit 12
How to derive measurements of mass flow rate that are essentially independent of frequency or amplitude of oscillations will be described with reference to the details of system 100 shown in FIG. As is clear from FIG. 9, the system 100 includes the speed sensor 3
Two channels are used, termed the measurement channel signaled by 0 and the reference channel signaled by speed sensor 28. The reference channel is
A preamplifier 102 is provided to boost the speed signal received from speed sensor 28 to an appropriate level. Preamplifier 140 operates similarly to preamplifier 1.2. The conduit drive circuit 1.4 receives the amplified velocity signal sent along line 148 from the preamplifier 102, suitably amplifies the amplified velocity signal to generate a drive signal, and generates a drive signal. is sent to coil 54 of conduit drive assembly 26 to vibrate conduit sections 18 and 20. The gain of conduit drive circuit 104 is controlled by automatic gain controller 106 such that the drive signal sent to conduit drive assembly 26 produces a desired amplitude of vibration in conduit section 18 .

The switched capacitor integrator 108 is connected to the preamplifier 10
Receives the amplified speed signal from 2.

A switched capacitor integrator 108 integrates the amplified velocity signal to generate an integrated velocity signal, a quadrature signal, which is used by a peak detector 110 to output a quadrature signal in a preamplifier 102. A peak amplitude of the generated amplified velocity signal is determined. In addition to generating a quadrature signal, switched capacitor integrator 108 improves the performance of system 100 through noise rejection. However, the inclusion of switched capacitor integrator 108 clearly increases the cost of system 100. The improved performance provided by switched capacitor integrator 108 is not necessary for system 100 to function properly, and a conventional integrator may instead be used in system 100. If switched capacitor integrator 108 is eliminated, any known device capable of generating a quadrature signal for peak detection purposes can be provided.

The signal generated by switched capacitor integrator 108 is also sent to auto-zero circuit 112. The auto-zero circuit 112 integrates the DC component of the signal generated by the preamplifier 102 and switched capacitor integrator 108 and returns the integrated signal to the terminal of the preamplifier 102, which is normally grounded. do. Accordingly, the accumulated DC offset generated or received by preamplifier 102 is removed, and the signal generated by preamplifier 102 becomes an AC signal with substantially no DC component. The switched capacitor integrator 109 and the automatic zero circuit 142 are similar to the switched capacitor integrator 1 described above.
08 and automatic zero circuit 112, respectively.

Peak detector 110 receives the amplified velocity signal produced by preamplifier 102 and the integrated velocity signal or quadrature signal produced by switched capacitor integrator 108 . Peak detector 110 includes preamplifier 102 and switched capacitor integrator 108.
generates positive and negative peak signals VPA representing the peak amplitude of the integrated velocity signal generated by VPA.

Peak detector 111 receives the amplified velocity signal generated by preamplifier 140 and switched capacitor integrator 109 and
A positive and negative peak signal VPB is generated representing the peak amplitude of the integrated velocity signal produced by VPB.09.

Automatic gain controller 106 receives the peak signal generated by peak detector 110 and converts the peak signal into
A reference level representative of the desired vibration amplitude of conduit 12 is compared. Automatic gain controller 106 generates a command signal representative of the difference between the peak signal and the reference signal and provides this command signal to conduit drive circuit 104 . With this command signal, the gain of the conduit drive circuit 104 is
The drive signal sent to the conduit drive assembly 26 by this circuit is adjusted to cause the conduit section 18 to vibrate at the desired amplitude.

Peak detectors 110 and 111, high precision comparators 114 and 126, D/A converters 116 and 130, direction controllers 128 and 134, phase comparator 118, digital counter 120, read only memory (ROM) 122,
Latch 132 in turn forms a closed loop feedback control system 124 . This control system 1
24 is a switched capacitor integrator 108 and 10
9 and generates a periodic comparison signal corresponding to each integrated velocity signal. Control system 124 shifts one of the comparison signals, the measurement signal, toward the other comparison signal, the reference signal, as necessary to eliminate the phase difference between the two signals. Record the amount. Therefore, the signal recorded is.

It is related to the phase difference between the two speed signals generated by speed sensors 28 and 30. This recorded signal is stored in digital counter 120 of control system 124. The change in phase difference between the two velocity signals that occurs when the fluid mass flow rate changes is represented by a corresponding phase shift between the comparison signals. system 1
24 changes the count stored in counter 120 to represent the new phase shift that exists between the comparison signals as it shifts the comparison signals to reduce the phase shift to essentially zero. Therefore, the count stored in counter 120 at steady state, or zero, conditions represents the total phase difference that exists between the velocity signals and, therefore, the current mass flow rate.

Generally, system 124 shifts the measured comparison signal toward the reference comparison signal until they are substantially in phase with each other. The measurement comparison signal is shifted by adjusting the value of the signal VTR. As can be seen from FIG. 10, increasing the value of VTR shifts the measured comparison signal toward the right, and decreasing the value of VTB shifts the measured comparison signal toward the left. As the count contained in counter 120 is increased or decreased, D/
The A converter 130 increases or decreases the value of VTB, respectively. When the mass flow rate changes, the speed sensor 28
The phase difference between the velocity signals generated by and 30 also changes correspondingly. High precision comparators 114 and 126 generate comparison signals with corresponding phase differences existing therebetween. During each cycle, the count of counter 120 is incremented or decremented and the level of the VTR is correspondingly incremented or decremented, respectively. As the level of the VTR increases or decreases, the measured comparison signals are shifted towards the left or right, always in a direction that reduces the phase difference between the comparison signals. This process continues until a zero condition is reached, in which both comparison signals are essentially in phase, and successive cycles of the measurement comparison signal shift the measurement signal to the right and left, causing the measurement comparison signal to shift to the right and left. The measurement signal is oscillated around the point where the signal is in phase with the reference comparison signal.

In other words, in the zero state, system 124 alternately increases or decreases counter 120 by one count and alternately advances or lags the measured comparison signal by a very small angle relative to the reference comparison signal.

In other words, in the zero state, system 124 alternately increases or decreases counter 120 by one count and alternately advances or lags the measured comparison signal by a very small angle relative to the reference comparison signal.

Counter 120 includes a measured count signal that is proportional to the mass flow rate of fluid flowing into conduit 12 when system 124 is in the zero condition. When the mass flow rate changes one more time, the comparison signals are out of phase with each other and the system 124 shifts the measured comparison signal toward the reference comparison signal so that the two comparison signals are essentially in phase with each other.

In particular, directional controller 134 receives a directional signal from counter 120 along lines 498 that corresponds to the direction of fluid flowing through conduit 12 .

When the flow direction is positive, i.e. in the direction indicated by the arrow in FIG.
The positive peak signal from 11 is sent to D/A converter 130. If the direction of fluid flowing through conduit 12 is negative, i.e., opposite to the direction indicated by the arrow in FIG.
A negative peak signal is transmitted from the D/A converter 130 to the D/A converter 130.

Directional controller 128 directs lines 50 from counter 120.
Receive a direction signal latched along 0. As discussed in more detail below, this latched direction signal maintains its value throughout operation of the flow system such that the velocity signal generated by sensor 28 is generated by sensor 30 during zero flow conditions. Indicates whether the speed signal is ahead or behind the specified speed signal. The velocity signals should be in phase with each other at zero flow conditions, but misalignment issues cause them to be out of phase.

D/A converter 16 receives a peak signal (VPA) from direction controller 128 and a 12-bit latch count signal (Y) along lines 496 from latch 132. This latch count signal Y represents the degree of flow meter misalignment at zero flow conditions. The value of the latch count signal is held constant during flow meter operation and is used to offset the effects of flow meter misalignment. D
/A converter 116 generates an analog threshold signal VTA, which is expressed as:

V ding A = K (Y /4096) V PA
(22) where is a constant between O and 1 used for scaling purposes, Y is the latch count signal generated by the counter 120 and ROM 122, and the constant 4096 is the Y
There is a numerical value (0 to 4095) 't'' that can be taken by V
PA is the peak signal generated by peak detector 110. Similarly, D/A converter 130 receives a peak signal (VPB) from peak detector 111 and a 12-bit measurement count signal (X') from counter 120 via lines 494. This measured count signal represents the mass flow rate of fluid flowing through conduit 12 under steady state conditions. D/A converter 13
0 generates a signal VTR expressed by the linear equation.

VTB=K (X/4096) VPB
(23) However, VTB is D/A:M/verter 13
0 is the signal generated, and X is the signal generated by the counter 12.
0 and the value of the measurement count signal generated by ROM 122, and VPB is the signal generated by peak detector 111. The equations of VTA and VTB are expressed as (2
0), we get the following:

KX/4096=sin[arcsin(KY/409
6)-2f (M)] (24) Solving for X gives the following.

X=[4096/nico sin[arcsin(KY/
4096)-2f (M)ko (2
5) is a 12-bit binary number whose magnitude is proportional to the force generated by the fluid flowing through the conduit 12 and the vibrations of the conduit 12;

The value of X is essentially independent of the amplitude of the velocity signals generated by velocity sensors 28 and 30, and therefore independent of the vibration amplitude of conduit 12. Furthermore,
The value of X is independent of the frequency W of the conduit 12 and thus independent of the frequency of the sinusoidal signals generated by the velocity sensors 28 and 30.

High precision comparators 114 and 126 and phase comparator 11
8 is operative to record the measurement count signal X in the counter 120. A precision comparator 114 receives the integrated speed signal from switched capacitor integrator 108 and receives VTA from D/A converter 116 . A precision comparator 114 compares the integrated velocity signal to VTA. FIG. 10 shows each high precision comparator 114
and 126 operations are shown. Comparator 114 generates a low level signal when the value of the integrated velocity signal is less than VTA, and generates a high level signal when the integrated velocity signal is greater than VTA. Therefore, high precision comparator 11
4 is shifted from the integrated velocity signal to the extent indicated by VTA. High precision comparator 126 is connected to switched capacitor integrator 10
9 and the VTR generated by D/A converter 130. High precision comparator 126 operates in the same manner as high precision comparator 114 operated to generate a measured comparison signal.

Generally, the output VTA of the D/A converter 116 is held at a constant value to generate a reference comparison signal that is consistent with the corresponding speed signal, toward which the measured comparison signal can be shifted. The measured comparison signal produced by comparator 126 is shifted toward the reference comparison signal by changing the value of the VTR.

As the measured comparison signal is shifted toward the reference comparison signal, counter 120 records the extent of the shift. Counter 120 is incremented or decremented once during each cycle of the measurement comparison signal. A phase comparator 118 receives the comparison signal and outputs a counter 12 during each cycle of the measured comparison signal.
Determine whether 0 should be incremented or decremented. Phase comparator 118 increments counter 120 if the measured comparison signal lags the reference comparison signal;
If the measured comparison signal leads the reference comparison signal, counter 120 is decremented. Therefore, when the system 124 is in the zero state, the value of X contained in the counter 120 is proportional to the force developed by the fluid flowing through the conduit 12 and can determine the magnitude of the mass flow rate.

Equation (25) shows that the measurement count signal X is non-linear. If desired, ROM 122 can be provided to make the count signal linear. ROM
122 is mapped as follows.

X=4096/K 5in (KX'/4096)
(26) Solving for X' gives the following.

X'=(4096/K) arcsin(KX/4096
) (27) When the equation for X found in equation (25) is substituted into equation (27), the following is obtained.

X' = (4096/K) [arcsin (KY/
4096)-2f (M)] (28) This is a linear expression for the count contained in counter 120. In a state where the flow rate is zero, equation (28) becomes as follows.

2 f (0) = arcsin (KY/4096)
(29) However, f(0) is f(M) in a state where the flow rate is zero. Therefore, it becomes as follows.

Y = (4096/K) sin [2f (0)]
(30) When the flow rate is zero, as long as the value of Y in equation (28) satisfies equation (30), the value of X' in equation (28) is zero. Therefore, X' can be expressed as:

X' = 4096/K [2f (0) - 2f (M) (31) The value of K is calculated by substituting the value of X' into equation (31) for the phase shift of all scales, and It can be determined by solving. However, it is necessary to convert from 1 degree to radians, and it is not noted that 2π radians = 360 degrees.

X' (4095)=4095=[4096/K][F
(3,14159)/3601 (32) where F is the full-scale phase shift (degrees) and 4095
is the value of X' when a full-scale phase shift is achieved. Solving for K, we get the following.

K = 0.017453292F
(33) arcsin (K Y /4096)
term occurs because there is a mismatch or misalignment between conduit sensors 18 and 20, sensors 28 and 30, and system 100. Due to these factors,
There will be a count on the counter 120 even under zero flow conditions. If the count when the flow rate is zero is left in the counter 120, the result will be inaccurate when the flow rate is flowing. The latch 132 is
It is provided to remove the count at zero flow rate from the counter 120.

The latch 132 receives the measurement count signal X from the ROM 122.
receive. Strobe latch 132 transfers the signal appearing at its input to its output. Initiating oscillation of conduit 12 at zero flow to eliminate counting at zero flow causes velocity sensors 28 and 30 to move relative to each other if there is a misalignment between the components of sensing assembly 10 and signal processing system 100. Generates a sinusoidal signal that is not in phase.

Press the zero switch 136 (Fig. 15) to reset the counter 12.
0 and causes the zero output to be latched into the latch 132. After some delay, control system 124 reaches a zero condition and causes counter 120 to accumulate a count representing the phase difference between the two speed signals produced by speed sensors 28 and 30. ROM 122 provides signal X to the input of latch 132, which is strobed to send the value of X to its output and maintain it as signal Y. D/A converter 116 by latch 132
Applying signal Y to VTA changes the value of VTA sent to high precision comparator 114. The reference comparison signal from precision comparator 114 is derived from the integrated speed signal received from switched capacitor integrator 108 at speed sensor 28.
and 30 by an amount corresponding to the phase shift that exists between the velocity signals generated by . This shift in the reference signal causes a difference in the phase of the input to the single phase comparator 118, which causes the counter 120 to begin counting toward zero. When counter 120 reaches zero, system 100 enters the zero state. The value of Y latched at the output of latch 132 ensures that the count X' generated by counter 120 accurately represents the mass flow rate.

11-15 are circuit diagrams illustrating circuits particularly useful in implementing the corresponding blocks shown in FIG. 9. Preamplifier 102 (FIG. 11) includes amplifier 200 and resistor 202. Preamplifier 102 (FIG. 11) includes amplifier 200 and resistor 202.

The velocity signal produced by amplifier 200 on line 204 is equal to the signal appearing on lines 206 and 208 (which is
(constituting the speed signal generated by speed sensor 28)
It is an amplification of the difference between

Resistor 202 determines the gain of amplifier 200 based on the following equation.

1 +40,000/RG (34)
However, RG is the resistance value of resistor 2o2.

A switched capacitor integrator 108 (FIG. 11) receives the amplified velocity signal along line 204 from preamplifier 102. Resistor 210, capacitor 212 and operational amplifier 214 form an inverting integrator 216. Without further compensation, the DC offset contained in the amplified speed signal received along line 200 by switched capacitor integrator 108 reduces the integrated speed signal produced by amplifier 200. increases or decreases, causing amplifier 214 to generate a DC signal equal to the level of the control voltage applied thereto. Therefore, the switched capacitor inverter 230
Sampling the output of the amplifier 214 generated at 18,
The DC component of the output of amplifier 214 is fed back along line 220 to amplifier 214. The amplifier 214 is
The accumulated DC signal appearing on line 220 is subtracted from the amplified speed signal to remove significant DC components from the integrated speed signal. The output of amplifier 2] 74 is sampled at a frequency of approximately IKHz to 5KHz. switch 222 and capacitors 224, 226 and 2
28 forms a switched capacitor inverter 230, the AC gain of which is approximately 0.001:1. A suitable lock signal is provided to establish the sampling frequency.

A signal is sent along lines 236 and 238 to time switch inputs 232 and 234 and cause switch 222 to switch at the frequency of the clock signal. Alternatively, switched capacitor inverter 2
30 internal clocks can be used as the switching signal, in which case the value of capacitor 228 determines the sampling frequency. When switch 222 assumes the state shown in FIG. 11, capacitor 226 is charged by the DC component of the integrated speed signal.

Upon receipt of the next clock pulse, switch 222 toggles its state and transfers the charge on capacitor 226 to capacitor 224 . Due to the difference in capacitance between capacitors 224 and 226, the voltage on capacitor 224 is approximately 1/1 OOO of the voltage on capacitor 226 after the charge on capacitor 226 is transferred to capacitor 224. Due to the grounded configuration of switched capacitor inverter 230, the voltage on capacitor 224 is always opposite to the voltage on capacitor 226. Therefore, line 22
The voltage sent to amplifier 214 along line 21
It works to reduce the DC deviation originally included in the signal of No. 8. Therefore, the DC gain of the integrator 216 is approximately 1,
The AC gain is substantially determined by the combination of resistor 210 and capacitor 212.

Auto-zero circuit 112 (FIG. 11) receives the integrated speed signal from switched capacitor integrator 108 and provides a signal operative to remove the DC component generated by amplifier 200 from the integrated speed signal. is supplied to the preamplifier 102. Amplifier 244, resistor 246, and capacitor 248 form an integrator with a long time constant (on the order of several seconds). Resistors 250 and 252 divide the output of amplifier 244 through capacitor 248 and resistor 246.
It operates by multiplying the time constant obtained by amplifier 2
The output of 44 is provided to a terminal of amplifier 200, which is normally grounded along line 256.

The peak detector 110 (FIG. 12) is connected to the preamplifier 102.
along line 258 and an integrated signal, ie, a quadrature signal, generated by amplifier 214 is received along lines 218, 260, and 262. Peak detector 110 uses the amplified velocity signal as a timing signal to indicate when peak amplitudes of the integrated velocity signal occur and to form the amplitude of the integrated velocity signal at these times. Resistors 264 and 266 and capacitor 268 create AC and DC hysteresis such that the edges of the signal generated from amplifier 270 occur simultaneously with the zero crossings of the amplified speed signal generated by preamplifier 102. do.

The signal produced by amplifier 270 on line 272 is high when the amplified velocity signal is less than zero and low when the amplified velocity signal is greater than zero. The output of amplifier 270 is connected to lines 272 and 2
74 to the inverting input of one-shot multivibrator 278, and lines 272 and 276.
is supplied to the non-inverting input of the one-shot multivibrator 280 along the line. One-shot multivibrator 278 generates a negative pulse or negative strobe signal each time the trailing edge of the signal generated by amplifier 270 occurs, and one-shot multivibrator 280 generates a negative strobe signal each time the trailing edge of the signal generated by amplifier 270 occurs. generates a positive pulse, or positive strobe signal, each time it appears. In Figure 12.

An integrated FET switch 282 is shown schematically. Switches 284, 286, 288 and 290 close when receiving low level signals on their inputs. Switch 284 of integrated switch 282 receives the negative strobe signal along line 292 and the integrated velocity signal along lines 262 and 296. Switch 286 of integrated switch 282 receives the positive strobe signal along line 294 and the integrated velocity signal along line 262. switch 284
Whenever switch input 298 of receives a negative pulse,
Switch 284 is closed during the pulse. Capacitor 302 charges to the level of the integrated velocity signal that occurs during the occurrence of the negative strobe pulse. Since each negative strobe signal occurs during the negative peak of the integrated speed signal, capacitor 302 is always charged to a voltage level equal to the then occurring negative peak value of the integrated speed signal. Similarly, switch 286 is
Switch 286 closes during each positive strobe signal it receives on human power 300. Since each positive strobe signal occurs when the positive peak amplitude of the integrated velocity signal occurs, capacitor 304
It is constantly charged to a voltage level equal to the positive peak value of the integrated speed signal. Switches 288 and 290 of integrated switch 282 provide a latched direction signal that indicates whether the speed signal generated by sensor 28 is leading or lagging the speed signal generated by speed sensor 30 during zero flow conditions. are received from counter 120 along lines 500 at their inputs 306 and 308.

Line 310 takes a low level value when the signal generated by sensor 30 lags the signal generated by sensor 28, and takes a high level value otherwise. line 3
The signal at 12 is low when the signal generated by sensor 30 leads the signal generated by sensor 28, and high otherwise. The direction signal is never high or low at the same time.

When the direction signal on line 310 is low, line 31
2 direction signal goes high and only switch 288 closes. The voltage on capacitor 302 is applied to buffer amplifier 31
4 input and represents the negative peak amplitude of the integrated velocity signal. When the direction signal on line 312 is low, the direction signal on line 310 is high and only switch 290 is closed. The positive voltage on capacitor 304 is sent to the non-inverting input of amplifier 314 and represents the positive peak amplitude of the integrated velocity signal.

Thus, when the direction signal on line 310 is low, amplifier 314 sends a negative signal along line 316 to D/A converter 116.

When the direction signal on line 312 is low, amplifier 314 sends a positive signal along line 316 to D/A converter 116 representing the positive peak amplitude of the integrated velocity signal.

D/A converter 116 receives a suitable peak amplitude signal along line 316 from direction controller 128 and a latched count signal Y generated by latch 132 along lines 496. 12th
The figure shows a general configuration for D/A converter 116.

D/A converter 330 is a commercially available D/A converter. D/A converter 116 generates a signal VTA on line 334 having the form expressed by equation (22).

Precision comparator 114 outputs signal VT along line 334.
A and the integrated velocity signal along line 260 to generate a reference comparison signal of the type shown in FIG. Comparator 336 receives both signals and generates a signal on line 338. This signal has a low level when the level of the integrated speed signal is higher than the VTA level, and has a high level at other times. Amplifier 34.0 generates a reference comparison signal on line 342. A resistor 344 is provided to limit the current, and Schottky diodes 346 and 348
The degree of input signal supplied to amplifier 340 is limited to increase the operating speed of amplifier 14.

The size of resistors 343 and 345 determines the total phase shift range provided by phase comparator 114, and thus:
The value of F in Equation 33, which determines the value of K, is determined.

Automatic gain controller 106 receives a positive peak signal VPA along line 350 from peak detector 110. Amplifier 352 receives the positive peak signal and resistors 351 and 35.
A command signal is generated on line 354 representing the integrated difference between the reference value of approximately 10 volts which is sent to amplifier 352 by a voltage divider formed by V.3. Conduit drive circuit 104 receives command signals generated by automatic gain controller 106 via line 356. The command signal on line 356 is the optical isolator 3
Received by 58. The amount of current flowing through LED 360 determines the conductivity of FET 362. FET36
The conductivity of 2 is proportional to the amount of current flowing through the LED 360. Since the gain of amplifier 364 varies proportionally to the conductivity of FET 362, the gain of amplifier 364 varies proportionally to the level of current flowing through diode 360. Typically, an output of approximately zero volts is produced on line 354 by amplifier 352, which indicates that the desired level of vibration in conduit 18 has been reached, and which causes a predetermined level of current to flow through diode 360 and 364 to a predetermined gain.

Increasing the vibration level of conduit 12 causes a more positive output to be generated by automatic gain controller 106, which
While reducing the current in diode 360, amplifier 36
Decrease the gain of 4. When the vibration level is lowered below the desired level, a more negative signal is generated by automatic gain controller 106, which increases the current in diode 360 and increases the gain of amplifier 364. The output of amplifier 364 is sent along line 366 to power drive circuit 368. Power drive circuit 368 suitably amplifies the signal generated by amplifier 364 to generate a drive signal and provides the drive signal along line 370 to coil 54 of conduit drive assembly 26 .

Preamplifier 14o, automatic zero circuit 142, switched capacitor integrator 109, peak detector 111, direction controller 134. The high precision comparator 126 and the D/A converter 130 have the same configuration as their corresponding parts described above.

13, 14, and 15 illustrate in detail the phase comparator 118, latch 132, and digital counter 120 shown in FIG. 9. Timing signal generator 37
2 generates a timing signal that controls the operation of counter 120. A 2 MHz crystal 374, a Nant gate 376, and a resistor 378 form the heart of a typical crystal oscillator 380. Inverter 382 inverts the signal generated by oscillator 380 and provides the inverted signal to the clock input of divider network 384 . Split network 384 splits the 2 MHz signal received from gate 382 and outputs a 1 MHz square wave on line 386.
and 388 occur. The signals on lines 386 and 388 are 180° out of phase with each other and thus form the basis of two separate timing phases.

Exclusive-OR gate 390 receives a +15 volt control voltage along lines 398 and 400 and a reference signal along line 342 from precision comparator 114. Exclusive-OR gate 392 receives a +15 volt control voltage along line 398 and a measured comparison signal along line 396 from precision comparator 126. Each gate 390 and 392 is connected to line 342
or generate a high level signal when the input of the 396 falls to a low value. The outputs of gates 390 and 392 are sent along lines 402 and 404 to phase comparator 118. The signal on line 404, i.e., the clock signal CLOCK
is used by counter 420 (FIG. 14) to
The count signal maintained by counter 420 indicates when it is changed and is used by phase comparator 118 to determine whether the measured comparison signal leads or lags the reference comparison signal. The signal generated on line 406 by phase comparator 118, ie, up/down signal UP/DN, is used to determine whether each change to the count should be made by increasing or decreasing the count. line 404 before the leading edge of the clock signal on line 404 reaches phase comparator 118.
When the signal No. 2 takes a high value, the UP/DN signal becomes high level. Before the signal on line 402 takes a high value, the leading edge of the clock signal on line 404 reaches phase comparator 11.
If 8 is reached, the UP/DN signal on line 406 goes low until the next cycle.

Flip-flop 408 receives the clock signal through gate 392. Flip-flop 408 is
Flip-flop 384 to lines 386 and 412
synchronizes the clock signal with a 1 MHz signal received along the Flip-flop 408 therefore generates a synchronized clock signal, ie, the 5YNCCLOCK signal, on line 414. This signal is connected to gate 392
equal in frequency to the signal generated by gate 39
2 and is 180 DEG out of phase with the signal generated by Flip-Flop 384 and synchronized to a 1 MHz clock signal generated at the Q' terminal of flip-flop 384. 5Y
The NCCLOCK signal is used to drive the binary counter of clock 120. When the CLOCK signal is synchronized with the signal generated on line 386 by flip-flop 384, rate multipliers 530, 532 and 534 are no longer timed while their inputs change. Flip-flop 416 connects phase comparator 118
and generates signal 5YNCUP/DN on line 418 by synchronizing the UP/DN signal with a 1 MHz noninverting signal generated at terminal Q by flip-flop 384. Therefore, the measurement comparison signal is essentially synchronized with one phase of the 1 MHz clock signal, and the measurement comparison signal is synchronized to the phase comparator 11.
The UP/DN signal generated by 8 is synchronized with the other phase of the 1 MHz tarok signal. 5YNCUP
/DN signal 418 determines whether the count generated by counter 420 should be incremented or decremented, and the 5YNCCLOCK signal on line 414
controls the timing of transfer of count data to the output of

Each time phase comparator 118 is timed, it determines whether clock 120 should be incremented or decremented and the UP on line 406
/DN signal to the appropriate level of logic "1" or "0". When the leading edge of the 5YNCCLOCK signal appears, a 12-bit binary counter 420 is timed and incremented or decremented based on the 5YNCUP/DN signal on line 418. The counter 420 has four 2
It includes advance counter units 422, 424, 426 and 428. These binary counter sections 422.424.42
6 and 428 receive the 5YNCCLOCK signal from flip-flop 408 along lines 414.430.432.434 and 436, respectively, and
18° 438.5YNCUP/DN signals are received along 440, 442 and 444, respectively. Counter 422.
424.426 or 428 increases or decreases based on the level of the 5YNCUP/DN signal whenever it receives a clock pulse and is enabled by a logic 'O' sent to its CIN input. Transfer the count to its outputs QO, Ql, Q2 and Q3. Therefore, if the 5YNCUP/DN signal sent to each counter 422, 424, 426 and 428 is high, the count stored in the counter will be incremented when the next leading edge of the 5YNCCLOCK signal is received. 5 sent to counters 422, 424, 426 and 428
If YNCUP/DN signal is low level, 5Y
When the next leading edge of the NCCLOCK signal is received, the count accumulated in the counter is decremented. counter 42
2. The outputs of 424 and 426 are the digital counter 42
1 generated by o (and thus counter 120)
It represents a 2-bit measurement count signal X'. counter 4
Terminal Q1 of 22 is the least significant bit, and the terminal Q1 of counter 426
Terminal Q3 is the most significant bit of the count signal. The output QO of counter 428 is a sign bit and is a direction signal indicating whether the flow in conduit 12 is in a positive or negative direction.

D/A converters 116 and 130 require positive binary inputs. Exclusive or gate 446°448 and 45
0 ensures that the binary inputs to D/A converters 116 and 130 are always positive, i.e. gates 446.448
and 450 so that the output always forms a positive 12-bit binary number.

Gates 446, 448 and 450 are connected to binary counter 42.
2. the outputs generated by 424 and 426, respectively;
and outputs QO of counter 428 and generates a measurement count signal X' at their output. Gate 446.4
48 and 450 perform an exclusive OR function on (i) the output QO of counter 428 and (11) each output QO through Q3 of each binary counter 422, 424 and 426. Therefore, when the output QO of counter 428 is high, indicating that the outputs of counters 422, 424 and 426 form a negative 12-bit binary number, gates 446, 448 and 450 At the output, a negative 12 bit number formed by counters 422, 424 and 426 is generated. When the QO small output of counter 428 is low level, gates 446, 448 and 4
50 does not convert the 12 bit numbers formed by counters 422, 424 and 426.

The output QO of binary counter 428 represents the direction signal sent to direction controller 134. Inverter 492 inverts the output QO of counter 428.

Form complementary directional signals. The direction signal and complementary direction signal are sent to direction controller 134 along line group 498.

The outputs of exclusive-OR gates 446, 448 and 450 forming signal X' are connected to latches 452, 454 and 4, respectively.
Sent to 56. Latches 452, 454 and 456 are
A latched count signal Y is generated on line group 496. As mentioned above, as shown in FIG.
Inclusion is optional. The system shown in FIGS. 11-15 does not include ROM 122 for linearizing count signal X. Therefore, X' is
be equivalent to. The measurement count signal can be linearized using a conventional ROM suitably programmed as described above.

The latched command is transferred to the latched offset switch 4.
72 is sent to the clock input of flip-flop 470. The Q output of flip-flop 470 is sent to the data terminal of flip-flop 474. The I MHz output of flip-flop 384 is
Flip-flop 4 along lines 476 and 478
Sent to 74. Therefore, the latch command is 5YNC
Synchronized with UP/DN signal. Latch commands always occur at alternating clock phases from where a change in effect occurs on the 5YNCCLOCK signal. The Q output of flip-flop 474 is connected to line 480 and line 4 each.
Latch 452.454 along 82.484 and 486
and 456. Latches 452.454 and 45
Each of 6 transfers the signal appearing on its input to its output when it receives a latch command on its clock input. The latch command generated by flip-flop 474 on its Q output is output on lines 480 and 490.
along to flip-flop 488. Flip-flop 488 receives the complementary direction signal generated by inverter 492. Therefore, whenever flip-flop 488 receives a latch command from flip-flop 474 on its clock input, flip-flop 488 outputs its Q and Q' ratio outputs, the latched direction signal and the complementary Each generates a direction signal. The configuration of flip-flop 470 allows the terminals of flip-flop 470 to be activated after the first latch command is generated and before flip-flop 470 is timed to generate the second latch command. Two latch commands cannot be generated one after the other unless a reset signal is supplied to R.

The measured count signal X' is transmitted along line group 494 to
The latched count signal Y sent to the A converter 130 is sent to the D/A converter 11 along line group 496.
Transferred to 6. The latched direction output is line group 5
00 to the direction controller 128, the direction output is
It is sent along line group 498 to direction controller 134 .

The outputs of latches 452, 454 and 456 can be reset to zero by operating reset switch 136, which generates a reset signal. Latch 452.
454 and 456 require the application of an inverted reset pulse to reset their outputs to zero.

Accordingly, the reset signal is inverted by inverter 502 to form a reset command, which is then sent to latches 452, 454 and 456. Reset signals are also provided on lines 499 and 601 and line 499, respectively.
．． Flip-flop 47 along 603 and 605
0 and 474 to enable a synchronized latch command to be generated by flip-flop 474. The reset signal is for each counter 422.424.426.
and input terminal R of 428 to reset these counters. Additionally, a reset signal is sent to the R input of flip-flop 488 to alternate the latched direction signal. To be able to establish the proper values of the Y signal and the latched direction signal, the reset switch 136 must be actuated upon start-up of the flow meter.

Response controller 504 monitors the number of consecutive count commands in the direction sent to counter 420 . That is,
The response controller 504 examines the number of consecutive increments or decrements that it commands the counter 420. If counter 420 is commanded to increase at least 16 consecutive times or decrease at least 16 times, response controller 504 causes counter 42 to
0 is incremented or decremented one after another in groups of 17 counts. If 16 more groups of 17 consecutive increment or decrement commands are given, response controller 504 causes counter 4
20 are increased or decreased one after another in groups of 273 counts. The response controller 504 continues to increment or decrement the counter 420 in groups of 17 or 273 counts until the 5YNCUP/DN signal causes the counter 420 to either stop incrementing and start decrementing or stop decrementing and start incrementing. , at which point the response controller 504 causes the counter 420 to begin incrementing or decrementing by one count. The response controller 504 also causes the counter 420 to stop counting at 17 counts or 273 counts when the direction of fluid flowing through the conduit 12 is reversed. Counter 510 is on line 4
14 and 512, which is driven by the 5YNCCLOCK signal when it is received. Counter 510 is reset each time it receives a reset signal along line 497, which causes the 5YNCUP/DN signal on line 418 to change state or when the output QO of counter 428 changes state to Occurs when indicating that the direction of flow has reversed.

While counter 510 is reset, 5YNCCL
Until at least 16 falling edges of the OCK signal are received by counter 510 before receiving the reset signal.
Outputs Q5 and Q6 of counter 510 are low.

The output Q' of each flop-flop 514 and 594 is high.

Since the co output of each binary counter 422 and 424 is high, the output of each AND gate 518 and 596 is high, the CIN input of each binary counter 424 and 426 is high, and these counters are Becomes inoperable. Therefore, binary counter 422 is the only binary counter that is enabled unless a carry condition exists, and counter 420 is incremented or decremented by one count. When the 5YNCCLOCK signal, or 16 falling edges of the Glock pulse, is received by counter 510 before the reset signal appears on line 497, the output Q5 of counter 510 goes high and flips along line 516. - Timing the flop 514. Output Q of flip-flop 514
' will be low, and the 0-N input of counter 424 will be low, enabling counter 424.

Therefore, both counters 422 and 424 are enabled, the clock pulses occurring on line 418 are registered by both counters 422 and 424, and the output of counter 420 is increased or decreased by 17 instead of 1. counter 510 before the reset signal appears on line 497.
If receives 16 more tarok pulses, then
Output Q6 of counter 510 goes low, flip-flop 594 is timed to generate its Q' small output low level signal, and counter 426's CIN input generates a low level signal. do. Therefore, counters 426, 424, and 422 are all enabled, and counter 420 increases or decreases its count by 273 counts instead of 17 or 1. When the level of the 5YNCUP/DN signal changes, resistor 522, capacitor 524, and exclusive-OR gate 526 generate a pulse on line 528, which causes OR gate 527 to generate a reset signal on line 497. Counter 510 and flip-flops 514 and 594 are reset, the outputs Q' of flip-flops 514 and 594 go high, and AND gates 518 and 596 provide high level signals to the CIN inputs of binary counters 424 and 426. , disables these counters and causes counter 420 to start counting one more time.

The same reset signal is generated on line 497 when the QO output of counter 428 changes state. capacitor 5
29, resistor 531 and exclusive OR gate 533 generate a pulse on line 535, which causes OR gate 5
27 generates a reset signal on line 497. Note that counter 510 accumulates the trailing edge of the 5YNCCLOCK signal. The decision to reset the response controller 504 based on the 5YNCUP/DN signal is made based on the 5YNCUP/DN signal.
NCC: Occurs on the trailing edge of the LOCK signal.

The outputs of exclusive-or gates 446, 448 and 450 are:
are sent to the inputs of binary flow multipliers 530, 532 and 534, respectively. Binary ratio multipliers 530, 532 and 534
together with a binary counter 536 forms an output interface 537.

Output interface 537 produces a particularly useful form of output from signal x'. In particular, interface 53
7 generates pulses at a low frequency proportional to the mass flow rate of fluid flowing through conduit 12. Therefore, using a suitable technique, the pulses generated by interface 537 can be accumulated to determine the mass of fluid flowing into conduit 12. Flow multipliers 530, 532 and 534 are connected in a standard cascade. Flow multipliers 5.3o, 532 and 534 receive another phase of the I MHz clock signal generated by oscillator 372. Multiplier 530 generates a pulse with a frequency fO expressed by the following equation.

f o= f 1(X)/4096
(35) where fi is the frequency of the clock signal received by interface 537, IMHz. The output fO of multiplier 530 is too high to be useful.

Therefore, fo is divided by counter 536 by a factor from 21 to 212.

If desired, a position sensor can be used to detect conduit movement rather than a velocity sensor. When using a position sensor, the mathematical derivation method of the equation solved by the present invention is the same as in the above case, but the term W representing the frequency of the conduit 12 does not appear as a multiplier in equation (18). .

A suitable position sensor is a linear variable displacement transducer.
Sa(LVDT) 1? be. , m(7)LVD
T is mounted at each location where speed sensors 28 and 30 are mounted. When detecting the movement of the conduit 12 using a displacement sensor instead of a speed sensor,
A preamplifier 102 generates an amplified position signal,
This signal must be shifted +90' before being applied to the drive assembly 26 to sustain the vibration. The drive force generated by assembly 26 is proportional to the drive current that assembly 26 receives, and thus lags the drive signal by 90'. The amplified position signal generated by preamplifier 102 is in phase with the drive force and thus lags the drive voltage signal by 90°. The amplified position signal generated by preamplifier 102 may be integrated before being sent to conduit drive circuit 104 to eliminate the phase shift between this signal and the drive signal. This integration can be done in one of two ways. First, the amplified position signal generated by preamplifier 102 can be integrated by integrator 146. Integrator 146
receives the amplified position signals along lines 148 and 150 and provides an integrated position signal along line 152 to conduit drive circuit 1.4. Or again,
Conduit drive circuit 104 may receive an integrated position signal along line 154 from switched capacitor integrator 108 . Similar compensation can be made using acceleration sensors rather than displacement or velocity sensors.

If an LVDT were to be used rather than a speed sensor, a number of changes would need to be made to the circuits of FIGS. 11 and 12. FIG. 16 shows LV useful for driving an LVDT.
The DT drive circuit is shown in detail. A 320 KHz clock signal is provided along line 542 to binary counter 540.

Binary counter 540 generates 20.10 and 5 KHz square waves at output terminals Q4, Q5 and Q6, respectively.

Therefore, the signals on lines 544, 546 and 548 are 3
It represents a binary number of bits, and its value changes sequentially from 0 to 7. The output of counter 540 is A of decoder 550.
, B and C inputs. Resistance 552, 554, 55
6 and 558 are connected in series between the positive control voltage and ground to send various portions of the positive control voltage to decoder 550.
Construct a voltage divider that supplies xi large inputs.

The voltage on resistor 558 is supplied to the xl and x7 inputs of decoder 550. The voltages on resistors 556 and 558 are provided to inputs x2 and x6 of decoder 550. resistance 55
4.556 and 558 voltages are provided to inputs x3 and X5 of decoder 550. Decoder 550 input x4
A full positive control voltage is applied to. Input XO is grounded.

With inputs to input terminals A, B, and C of decoder 550, decoder 550 sequentially applies the voltages appearing at terminals x1 through XO to its Q output.

Each time a rising edge of the signal appears on any of terminals A, B, and C, decoder 550 passes it to the next xi large input Q output. As is clear from FIG. 16, the input XO receives zero voltage because it is grounded. Input x4 is
Receives full positive control voltage. Inputs x1 and xl each receive 15% of the positive control voltage. input x2 and x6
each receives 50% of the positive control voltage. Input x3
and x5 each receive 85% of the positive control voltage.

Therefore, when the binary counter 540 sequentially sweeps through the possible values of its 3-bit output, the Q of the decoder 550
The output sweeps through the voltage levels appearing at its xi large inputs, and a stepwise approximation of the sinusoidal signal appears at the Q output. The voltage at terminal XO represents the negative peak of the cycle;
The voltage at input terminal x4 represents the positive peak level of the cycle, and the voltage at input terminal x1. The voltages appearing at x3 through x3 and x5 through xl represent the midpoint values of the cycle. The stepped sinusoidal signal generated by decoder 550 is capacitively coupled to the input of complementary pair 560 via capacitor 562. Complementary pair 560 provides current gain and L
It has a sufficiently low impedance to drive the VDT's primary circuit. Capacitor 564 and resistor 566 are
The stepwise approximation sine wave generated by decoder 550 is smoothed.

The 5 KHz signal appearing at the Q6 output of binary counter 540 is sent to flip-flop 568. counter 5
The 640 KHz signal generated at the Q2 output of 40 is sent to the clock input of the second flip-flop 570. Flip-flops 568 and 570 generate a series of pulses, or strobe signals, each of the width of which is sent to flip-flop 570.
The period of the signal is KHz. Each pulse is sent to the decoder 5
It is timed to occur when the 50 x 4 input voltages appear at the Q output of decoder 550.

Therefore, a pulse occurs simultaneously with the positive peak of the drive signal generated by complementary pair 560.

FIG. 17 shows an LVDT demodulator.

Since the components of channels A and B are the same, only channel A will be described in detail. The LVDT demodulator shown in FIG. 17 receives the sinusoidal position signal generated by the LVDT sensor on line 570. The signal on line 570 is a high frequency signal that is amplitude modulated at the location of the conduit at the point where the LVDT sensor is secured to the conduit. The LVDT demodulator therefore produces a signal corresponding to 172 of the envelope of the signal appearing on line 570. The signal generated by the LVDT sensor is sent along line 570 to amplifier 572. Amplifier 572 and resistors 574 and 576 form a non-inverting amplifier with a gain of approximately 2.5. The output of amplifier 572 is
It is sent to the source terminal of ET switch 578. The output appearing at the drain terminal of FET 580 of FET switch 578 is sent to an amplifier 582 with a gain of approximately 2.5, the input of which is held by capacitor 584. FET
The gate of 580 is controlled by the output of amplifier 586. Amplifier 586 receives the strobe signal generated by flip-flop 570 (FIG. 16). The inverting input of comparator 586 is held at approximately 1/2 of the positive control voltage source by resistor 588. Therefore, comparator 58
When a 1.6 microsecond pulse is received by the non-inverting input to 6, the output of comparator 586 is pulled from the negative control voltage and is normally held at the positive control voltage by resistor 590. FET 580 turns on and the input sent to channel A is amplified by a factor of approximately 2.5 times, charging capacitor 584 to the voltage appearing at the output of amplifier 572. At the end of the 1.6 microsecond pulse, F
ET 580 is turned off and capacitor 584 retains its charge. The voltage on capacitor 584 is applied to amplifier 582.
and held at that level until amplifier 586 receives the next pulse. Also, the circuit 592
constitutes a level translator that can use CMOS levels.

The operation and properties of channel B are similar to channel A. The output of the LVDT demodulator represents a periodic position signal corresponding to conduit motion and is sent to preamplifiers 102 and 140 as shown in FIG.

Particularly suitable commercially available circuit components are indicated by manufacturer's part numbers, and suggested values for a number of circuit elements are shown in the drawings.

It should be noted that the circuitry shown in FIGS. 13, 14 and 15 may be replaced by a suitably programmed general purpose microprocessor.

Furthermore, a latch 132, a digital counter 120, a ROM
122 and auto-zero circuit 142 may also be replaced with a suitably programmed general purpose microprocessor. 21-30 are flowcharts of suitable computer programs for a microprocessor.

FIG. 31 shows a microprocessor or control board 1000 operated with the program shown in FIGS. 21-30, together with its outputs and the components of system 100 (FIG. 9) with which this microprocessor communicates. It shows. The system of FIG. 31, along with the parts of FIG. 9 not shown in FIG. 31, are referred to herein as system 200. FIG. 32 shows microprocessor 1000 in detail.

The microprocessor 1000 generates a phase comparator 118 which is a series of commands that increment or decrement the measurement count signal.
is received along line 1002. The signal generated along line 1002 by phase comparator 118 determines whether the program increments or decrements measurement count signal X. Moreover, the microprocessor 1000 is
A two digit (decimal) mode signal is received along line 1006 from manual mode switch 1004. This mode signal determines in which of a number of modes the program operates. Therefore, the operating mode of the program is established by appropriate operation of the mode switch. Microprocessor 1000 receives a zero signal along line 1008 that is generated by zero switch 1010 when it is activated. With this zero signal, a new latch count signal Y is calculated and used by the program. As mentioned above, the latch count signal is

3 represents the no-flow offset of flowmeter 10 due to mechanical and electrical noise. This latch count signal forces the measurement count signal to zero under no flow conditions.

Therefore, the calculation of zero, or in other words, the new determination of the no-flow offset, is performed when the zero switch is operated and the enable switch is set appropriately. microprocessor 1
000 receives an authorization signal along line 1012 from authorization switch 1014. The permission switch 1014 is
The permission signal is the first when it is appropriate to calculate a new Y.
A suitable switch that allows it to assume a state and assumes a second state when it is not appropriate to calculate a new Y. When the grant signal is in its second state, the program does not establish a new latch count signal. Enable switch 1014 may be a simple manual switch or an automatic flow sensor that can establish a new value for Y upon closing a valve that forces the flow through meter 10 to zero. good. Microprocessor 1000 generates an error signal along line 1016, the value of which is based on the nature of the error that generated it. The microprocessor 1000 has a temperature sensor 10
A temperature signal is received along line 1018 from 20.

Temperature sensor 1020 is placed on the wall of conduit 12 and thus monitors the temperature of conduit 12. line 1
The value of the temperature signal appearing at 018 is the value of the temperature signal appearing at temperature sensor 1020.
changes with the temperature sensed by.

This temperature signal causes the program to change the output and, in turn, the elastic modulus of the conduit 12 based on temperature. Microprocessor 1000 is on line 1
022 to generate an output signal.

This output signal represents a measured count signal that has been modified to represent the effect of the temperature of conduit 12 as sensed by temperature sensor 1020.

This output signal is transmitted along line 1022 to binary flow multiplier 530. of output interface 537 (FIG. 15).
532 and 534. The 12-bit output signal is sent to binary quantity multipliers 530, 532 and 534, which determine the frequency of the output of binary counter 536, as described above. Therefore, binary counter 536
The output frequency fo' can be expressed as follows.

fo'=fi(output signal)/4096 (
36) where fi is the frequency I M Hz of the clock signal received by the interface 537 and the output signal is the measurement count signal X and the temperature sensor 10
20.

The following variables are used by the program.

MODE: This is an 8-bit variable whose value is derived from the two-digit (decimal) mode signal established by mode switch 1004. 8 of MOD E
Bit has the following meaning.

One bit O and 1: indicates one of the four minimum values for the variable RESULT (which generally corresponds to the measurement count signal). Below that, the program indicates that the flow in flow meter 10 is zero.

Bits 2 and 3: Can be used by appropriately designed TEST subroutines.

- Bit 4: Indicates whether the variable MC0UNT (which generally corresponds to the measurement count signal) should be increased or decreased by a value greater than 1 for each command generated by the phase comparator 118.

One bit S: Indicates whether the output signal should represent a compensation of the temperature sensed by temperature sensor 1020.

Indicates whether temperature compensation should be performed using 1-bit 6-duplex resolution.

Bit 7: Indicates whether the program should perform a test measurement or a normal measurement.

MC0UNT: This is used by the program to represent the mass flow rate of fluid flowing into the flow meter 10]
, is a 6-bit variable. This MCOUNT is incremented or decremented each time a command is received from phase comparator 118. Bits O through 11 of MC0UNT correspond to the magnitude of the mass flow rate, and bit 15 represents the direction of fluid flow through the flow meter 10.

MDAC: This is a 16-bit variable whose bits 0-11 correspond to bits 0-11 of MC0UNT.
corresponds to MDAC is provided to D/A converter 130 and represents the measurement count signal X.

MDIR: This is an 8-bit variable whose bit O
is sent to the directional controller 134 and represents a directional signal, ie, the direction of fluid flowing into the flow meter 10.

RCOUNT: This is a 16-bit variable used by the program to represent the no flow offset of the flowmeter 10. Bits 0 through 11 represent the magnitude of the offset, and bit 15 represents the sign of the offset.

RDAC: This is a 16-bit variable whose bits 0-11 correspond to bits 0-11 of RCOUNT.
corresponds to RDAC represents the latched count signal Y sent to D/A converter 116.

RDIR: This is an 8-bit variable whose bit O is sent to the direction controller 128 and represents the latched direction signal, ie, the direction of the no-flow offset of the flow meter 10.

XC0UNT: This is ABSOLUTE VALUE
(Absolute value) This is a 16-bit variable on which the subroutine operates. When the program executes this absolute value subroutine, it uses XC0UNT to set MC0UNT or RC
Represents OUNT.

XDAC: This is a 16-bit variable whose value is established by the absolute value subroutine described above.

The absolute value subroutine determines whether the XDAC is
Bits 0 to 11 of T are taken or their two's complement is taken. Therefore, a variable (MDAC or RDAC) that receives a value specified in the XDAC is interpreted by the D/A converter 116 or 130 as a positive number.

XDIR: This is an 8-bit variable generated by the absolute value subroutine. Absolute value subroutine, XD
Cause IR to take the value of XC0UNT(7) bit 15. Therefore, XDIR represents the direction of fluid flowing into flow meter 10 if the value of XC0UNT is derived from MC0UNT for execution of the absolute value subroutine;
The value of XC0UNT, when derived from RCOUNT, represents the sign of the zero flow offset for flowmeter 10.

ZERO=This is an 8-bit variable used by zero switch 1010 to indicate whether a new zero calculation is requested. That is, ZERO indicates whether a new zero flow offset, or RCOUNT, calculation is requested.

AVE: This is an 8-bit variable whose bit O is used to indicate whether a new zero flow offset calculation is requested and has not yet been performed.

STEM: This is an 8-bit variable that indicates whether the enable switch 1014 has been set to allow a new zero flow offset calculation to be performed.

12 This is an 8-bit variable used by the ZERO subroutine as a timer to establish a time delay of approximately 255 (1/f conduit) seconds after a new zero flow offset calculation is requested. However, f
conduit is the frequency of the conduit 12.

, M-: This is an 8-bit variable used by the MODE subroutine. M is used as a counter or timer to allow the mode switch to be set mechanically before a new value for MODE is derived from the mode switch.

LMODE:,: is an 8-bit dummy variable used by the MODE subroutine.

NMODE: This is an 8-bit variable that receives the mode signal from mode switch 1004 and therefore represents the currently desired program operating parameters. N
MODE is used by the MODE subroutine.

PCOMP: This is an 8-bit variable that represents the command generated by phase comparator 118 and thus indicates whether M, COUNT, should be increased or decreased.

M'3 This is used to register the number of successive increments of MC0UNT commanded by 118 in the phase comparator.
This is an 8-bit dummy variable used by the LERATOR subroutine.

DWN: This is used to register the number of consecutive decreases in MC0UNT commanded by 118 to the phase comparator.
This is an 8-bit dummy variable used by the ELERATOR subroutine.

5NAFU: This is an 8-bit variable used to indicate the existence and nature of errors that occur during the execution of a 5 program.

DFAC: This is an 8-bit dummy variable used by the MASS subroutine.

This value of DFAC is the value of RE when temperature compensation is not required.
Used to change the value of MDAC to obtain SULT. The value of DFAC is typically 1.

FAC: This is an 8-bit variable that takes the value of DFAC or, if temperature compensation is required, the temperature compensation coefficient (TFAC:). FAC is multiplied by MDAC to form RESULT.

TEMP: This is an 8-bit variable generated by temperature sensor 1020. This TEMP is MA, S
Used by the S subroutine.

TFAC: This is the value derived from the temperature table8
Pi1 - variable. The appropriate position for the temperature table is TE.
Accessed using MP variables.

RESULT: This is a 16-bit variable used to generate the output signal. This RESULT represents the temperature compensated value of MC0UNT if temperature compensation is requested.

Length: This is an 8-bit dummy variable used as a counter by the AVE subroutine.

N: This is an 8-bit variable used as a counter by the AVE subroutine.

AVG: This is used to determine when the appropriate value of RCOUNT is established during the new zero flow calculation.
It is a 16-bit variable used to accumulate 128 successive readings of UNT.

FIG. 32 shows the configuration of the microprocessor 100o. The configuration of microprocessor 1000 is conventional and the operation of its components shown in FIG. 32 will be readily apparent to those skilled in the art.

At any time, the program is running as shown in FIG.
AIN (main) routine, ZER shown in Figure 22
O (zero) routine and POWER shown in FIG.
(power supply) to operate in one of the routines. The operation of each routine is initiated by a program interrupt. C.L.
The OCK interrupt starts execution of the main routine. The zero interrupt starts execution of the zero routine. A power interrupt initiates execution of a power routine. Power interrupts have the highest priority and clock interrupts have the lowest priority. A clock interrupt occurs each time a command is generated by phase comparator 118 (a command is generated by phase comparator 118 for each vibration of conduit 12). When phase comparator 118 sends a command to microprocessor 1000 along line 1002, the program increases or decreases MC0UNT based on the nature of the command.

At block 1026, when a clock interrupt occurs, the main routine executes the mode subroutine at 1028. As discussed in more detail below, the mode subroutine determines whether mode switch 1004 has been changed to request a new mode of operation for the program. At block 1030, bit 7 of the MODE established by the mode subroutine when a request for a new mode of operation is issued by the mode switch 1004.
is tested to determine whether normal operation or test operation should be performed. If bit 7 is set, a test operation is performed at 1032. I will not discuss the nature of test subroutines here, but
This is an appropriate subroutine to test the program.

If bit 7 is reset, ACCELERA
A TOR subroutine is executed at 1034.

As detailed below, this ACCELERATO
The R subroutine increases or decreases M COtJ N T based on commands received by microprocessor 1000 from phase comparator 118 . block 1
At 036, MC0U is the current value of the measurement count signal.
The value of NT is moved to dummy variable XC0tJNT. At block 1038, the absolute value subroutine is executed. In this case, in the absolute value subroutine, M
Bits 0 to 11 of C0UNT are entered and XDIR
Bit 15 of MC0UNT is placed in MC0UNT. block 1
In 040, XDAC (71 value is moved to MDAC,
The value of XDIR is moved to MDIR. Therefore 1MDA
C is the magnitude of the mass flow rate, i.e. the measured count signal X)
, and MDIR represents the direction of fluid flowing into the flow meter 10 (i.e., the direction signal).

In block 1o42, the variable ZERO is checked. If ZERO is set, the program proceeds to block 1044. If ZERO is reset, the MASS subroutine is executed at block 1046. As discussed in more detail below, the MASS subroutine modifies the measurement count signal based on the temperature provided by temperature sensor 1.20 if temperature compensation is required. RCOUNT to recalculate the zero flow offset if ZERO is set.
is requested to be recalculated, and this causes permission switch 101 to be recalculated.
This recalculation is performed if allowed by 4 and AVE is reset. If ZERO is set, AVE is checked at block 1044.

If AVE is reset, the ZERO subroutine is not executed because recalculation of the zero flow offset is required, and the ZERO subroutine returns to block 1.
It is executed at 050.

As discussed in detail below, in the ZERO subroutine, RCOUNT is roughly adjusted, i.e., RCOU
NT is made to take a value close to the zero flow offset of the flow meter 10 under zero flow conditions. If the AVE flag is set, then the ZERO subroutine was executed following the most recent request to calculate a new zero flow offset, and the AVE subroutine returns to block 10.
48. As detailed below, AVE
In the subroutine, RCOUNT is fine-tuned to more accurately represent the zero flow offset of flow meter 10.

FIG. 22 shows the ZERO routine.

A ZERO interrupt occurs at block 1052 each time zero switch 1010 is operated to indicate that a new calculation of RCOUNT is required in response to a request to recalculate the zero flow offset of flow meter 10. If the program is running in the main routine and a ZERO interrupt occurs, the program immediately proceeds to block 1052. The program then reads the STEM variables generated by permission switch 1014 at block 1054 . If STEM is set, the state of the permission switch indicates that a new calculation of RCOUNT is permitted, preferably meaning that the flow meter 10 is actually at zero flow, and the program returns to block 1056.
Then proceed to block 1058. If the STEM is reset, the new calculation of the zero flow offset for the flow meter 10 is inappropriate and the program returns to the main routine. If calculation of a new zero flow offset is permitted, then at block 1058 an electronically erasable programmable read-only IMoU (EEP
The current value of RCOUNT stored in ROM) is XC0.
Transferred to UNT. The absolute value subroutine is block 1
At 060, the contents of bits 0 to 11 of XC0UNT, which act on XC0UNT and represent the current value of the offset, are transferred to
The contents of bit 15 of 0UNT are moved to MDIH.

At block 1062, the XDAC(7) value is moved to RDAC and the XDIR value is moved to RDIR.

Therefore, RDAC and RDIR each contain the magnitude and sign of the offset represented by RCOUNT.

At block 1064, ZERO is set so that the program executes the zero subroutine on its next pass through the main routine, and T is set to O to initialize the timer used for the zero subroutine. The program exits the zero routine at block 1066.

FIG. 23 shows the POWER routine. The POWER interrupt occurs when the flow meter 10 is first powered or when powered following a temporary power outage. At block 1068, when the POWER interrupt occurs, the program immediately returns to block 1070.
Move to. At block 1070, 0 is moved to variable M;
The next time the program passes through the main routine, M is initialized when the MODE subroutine is executed. The value 80 (hex) is moved to MODE and the value 0 (16
The value established by the mode switch 1004 by the MODE subroutine is transferred to L M OD E .
It will be transferred to ODE.

At block 1072, the PIA 1024 is initialized to prepare the program for operation by initializing all counters and registers so that they are started in the proper order when power is applied or restored to the flow meter 10. do. In blocks 1074° 1076 and 1078, R
COUNT EEPROM contents are RDAC and RD
Transferred to IR. At block 1074, RCOUNT
The value stored in EEPROM is moved to XC0UNT. The absolute value subroutine, at block 1076, sets the XDAC and
Set the value of DIR. At block 1078,
The IR and XDAC values are moved to RDIR and RDAC, respectively. Line 50 by microprocessor 1000
It is necessary to establish appropriate values for RDAC and RDIR in order to transfer the appropriate signals along 0 and 496 to direction controller 128 and D/A converter 116, respectively. The program exits the POWER routine at block 1080.

FIG. 24 shows the MODE subroutine. In this MODE subroutine, the mode switch is read and a determination is made whether a change of mode is requested. If a mode change is requested, the mode subroutine establishes a wait time during which the program
before a new mode is established by updating the value of MODE.

The mode switch 1004 is mechanically rested.

If another new mode is requested by the mode switch 1004 during this standby time, the standby time is restarted, allowing the mode switch 1004 to mechanically rest again. When the standby time ends, the new mode value determined by mode switch 1004 is set to MO.
Transferred to DE.

The MODE subroutine begins at block 1082. At block 1084, the mode switch 1004
is read and the mode signal generated by mode switch 1004 is transferred to the NMODE variable. At block 1086, MODE and NMODE are compared with values that establish the operating mode in which the program is currently operating.

If N'MODE is equal to MODE, no new operating mode request has occurred and the program returns to the main routine. If NMODEfJ<MoDE, then a request for a new mode of operation has occurred, in which case, at block 1088, NMOD
E is compared to LMODE. The LMODE variable is a dummy variable that is not equal to NMODE the first time the program passes through the MODE subroutine following a request for a new mode of operation. If LMODE is not equal to NMODE, then in block 1090 the value of NMODE is equal to LMODE.
DE so that the appropriate branches are taken from block 1088 during the program's next pass through the MODE subroutine. Also at block 1090, the variable M is set to 0 to establish the start of the wait time.The program then proceeds to the main routine via block 1098. During the program's next pass through the main routine, block 1028 causes the program to again proceed to block 1082, the MODE subroutine. During this time, block 1088 causes the program to proceed to block 1092. This is because when the program previously passed through the MODE subroutine, N
This is because MODE is set equal to LMODE.

In block 1o92, variable M is incremented by one. At block 1094, it is determined whether M is equal to ten. If M is not equal to 10, the wait time has not been exceeded and the program returns to the main routine. The program repeats the MAIN routine and MODE subroutine until M equals 10, at which point the wait time is over and from block 1094 the program proceeds to block 1096. Block 1096 moves the value of NMODE to MODE to establish a new mode of operation for the program. Block 1096 also sets M to O to initialize M for the next execution of the mode change operation.

The program exits the MODE subroutine at block 1098.

FIG. 25 shows the ACCELERATOR subroutine. This ACCELERATOR subroutine uses MC0U in response to commands received from phase comparator 118 to increment or decrement the measurement count signal.
NT is increased.

Additionally, the increase or decrease of MC0UNT can be accelerated if a predetermined number of consecutive commands to increase or decrease are received by microprocessor 1000. The first to increase the measurement count signal
When six consecutive commands are received, rather than M COUNT being incremented by one count for each command received until microprocessor 1000 receives a command to decrement the measurement count signal.
MC0U by AC, CELERATOR subroutine
NT begins to be incremented by 16 counts. When the 32nd consecutive command to increment the measurement count signal is received, the MC
0UNT begins to be incremented by 256 and MC0UNT continues to be incremented by 256 for each command to increase the measurement count signal until the microprocessor 1000 receives a command to decrease the measurement count signal6.
Similarly, receiving 16 consecutive commands to decrease the measurement count signal causes the ACCELERATOR subroutine to decrease MC0UNT by 16 instead of 1, and receiving 32 consecutive commands to decrease the measurement count signal causes ACCE LERAT until a command is received to increment the measurement count signal.
The OR subroutine decrements MC0UNT by 256 instead of 1 or 16.

The program starts at 1100 with ACCELERATO
Enter the R subroutine. At block 1102, the variable P
COMP is read. That value is obtained from the commands that microprocessor 1000 receives from phase comparator 118. The value of PCOMP changes each time microprocessor 1000 receives a command from phase comparator 118 based on the nature of the command. If microprocessor 1000 receives a command from phase-comparator 118 to increase the measurement count signal, P
The value "1" is written to COMP.

Alternatively, if microprocessor 1000 receives a command from phase comparator 118 to decrease the measurement count signal, rOJ is written to PCOMP. At block 1104, it is determined whether MC0UNT should be increased or decreased. If PCOMP is equal to 1, MC0UNT is incremented and the program proceeds to block 1106. microprocessor 100
When the next command is received from the phase comparator 118 that 0 decrements the measurement count signal, the ACCELERAT
The OR subroutine causes successive commands to decrease the measurement count from 1 to the signal to begin counting appropriately. At block 11o8, it is determined whether increased acceleration is desired by examining bit 4 of MODE. MODE
If bit 4 of MC:0UN is set, no acceleration is desired and the program continues to block 1110
T is increased by 1. If bit 4 of MODE is reset, acceleration is desired and the program proceeds to block 1112. At block 1112, UP is incremented by one. UP has been initialized to O by the most recent command to decrease the measurement count signal. Therefore, the first command to increase the measurement count signal causes the program to increase UP to 1 at block 1112. At block 1114, it is determined whether UP is greater than 15. If UP is less than or equal to 15, then the number of consecutive commands to increment the measurement count signal received by microprocessor 1000 is sufficient to warrant accelerated counting operation, and the program proceeds to block 1110 where MCOU N T is increased by 1. If UP is greater than 15, acceleration is guaranteed;
At block 1116 it is checked whether UP is greater than 31. If UP is less than or equal to 31, microprocessor 1000 sends consecutive commands to increase the measurement count signal, but not enough to guarantee 256 accelerated count operations, but sufficient to guarantee 16 accelerated count operations. I received only a certain number of items. The program proceeds to block 1118, where MC0UNT
It is determined whether the value of MC0UNT is large enough that an overflow condition would occur if MC0UNT were increased by 16. MC0UNT is hexadecimal and FF01 is 4 in decimal.
If equal to or greater than 080, MC0
Increasing UNT by 16 causes MC0UNT to exceed the system limit of 4095, and the program proceeds to block 1110 where MC0UNT is increased by 1. Mc.

If UNT is less than FF○ (hex), block 1118 causes the program to proceed to block 1120 where MC0UNT is incremented by 16.

If UP is determined to be greater than 31 at block 1116, then the program sets MC0UNT to 25.
Increased by 6. However, the program is block 1
Proceeding to 122, it is determined whether lMC0UNT is less than FOO (hexadecimal), ie 3840 (decimal). If MC0UNT is less than 3840 (decimal), 256 can be added to MC0UNT without exceeding the system limit of 4095, and the program proceeds to block 1124 and sets MC0UNT to 256.
increase only. If MC0UNT is greater than or equal to 3840, adding 256 to MC0UNT will result in MC0U
NT exceeds 4095, therefore MC0UNT is 256
Only not increased.

The program proceeds to block 1118. As mentioned above, the program at block 1118 sets the MC:0U
Decide whether to add 16 or 1 to NT.

If PCOMP is determined to be equal to O at block 1104, the measurement count signal must be decremented and the program proceeds to block 1126. Block 11
At 26, O is moved to UP to ensure that the ACCELERATOR subroutine functions properly the next time microprocessor 1000 receives a command from phase comparator 118 to increment the measurement count signal. At block 1128, it is determined whether an accelerated count operation is desired by examining bit 4 of MODE. If bit 4 is set, no acceleration is desired and the program proceeds to block 1130, where MC0
UNT is increased by 1. If bit 4 is reset, the program proceeds to block 1132. Blocks 1128, 1130 and 1132 through 1138 are configured based on the number of consecutive commands that the microprocessor 1000 receives from the phase comparator 118 to decrease the measurement count signal described above as represented by the value of DWN. .1114.
1116.1118.112o, 1122 and 1124
operates in the same way that 4 decreases MC0UNT by 1.16 or 256. The program exits the AccELERATOR subroutine at block 140 and returns to the main routine.

FIG. 26 shows the absolute value subroutine. The absolute value subroutine establishes the value of the XDAC. The absolute value subroutine puts 0 in the lowest 4 bits of XDAC and stores the lowest 1 of XC0UNT in the highest 12 bits.
Insert 2 bits.

XDAC can be used by other routines or subroutines
transferred to DAC or RDAC. D/A converter 11
6 and 130 operate on the 12 most significant bits of RDAC and MDAC, respectively.6 Also, the absolute value subroutine places the most significant bit of XC0UNT into XDIR.

XDIR can be read by another routine or subroutine.
DIR or MDIR, which are used to provide appropriate directional information to directional controllers 128 and 134, respectively.

The absolute value subroutine is entered at block 1142. Block 1144 sets bit 15 of XC0UNT to
Move to R. Therefore, if RCOUNT is moved to XC0UNT before the program enters the absolute value subroutine, then XDIR represents the zero flow offset, ie, the sign of the latched count signal. MC0UNT is set to XC0UN before the program enters the absolute value subroutine.
When moved to T, XDIR represents the direction of fluid flowing into flow meter 10, ie, the sign of the measured count signal. Block 1146 indicates that bit 15 of XC0UNT is
Determine whether it is equal to bit 12 of C0UNT. Since the system limit is 4095 (decimal), all counting operations must be performed on the least significant 12 bits of MC01JNT and RCOUNT. Therefore, XC0
Bits 12, 13 and 14 of UNT must be 0 when XC0UNT represents a positive count signal. On the other hand, bits 12, 13 and 14 of XC0UNT are
XC0UNT must be 1 when it represents a negative signal. Bit 15 is 0 for positive count signals and 1 for negative count signals, so
Bit 15 of C0UNT is always bit 1 of XC0UNT
Must be equal to 2. Otherwise, XC0UN
T represents a signal greater than the 4095 system limit and an overrange condition occurs. If it is determined at block 1146 that bit 15 is not equal to bit 12, then the value of variable 5NAFU is sent to line 1016 as an error signal. Also, at block 1148, F
FFF (hex) is sent to XC0UNT, which causes output interface 537 to indicate zero mass flow. If bit 15 is equal to bit 12, then no overrange condition occurs and block 1150
determines the sign of XC0UNT. If bit 15 of XC0UNT is not 0, the sign of XC0UNT is negative, a two's complement of XC0UNT is formed in block 1152, and a positive binary number representing the magnitude of XC0UNT is sent to D/A converter 116 or 130. Allow it to be sent. If bit 15 of XC0UNT is equal to 0, then XC0UNT represents a positive number and no further processing of XC0UNT is necessary to cause a positive number to be sent to D/A converter 116 or 130. Block 11
54, XC0UNT is shifted 4 positions to the left and
:The lowest 12 bits of 0UNT are moved to the highest 12 bits of XC0UNT. Then XC0UNT is XDA
As a result, the lowest 4 bits of XDAC are set to 0, and the highest 12 bits of XDAC are set to 0.
It is made to represent the size of 0UNT. The program exits the absolute value subroutine at block 1156. The program then returns XC0UNT to RCOUNT
Depending on whether the T(7) value or the value of MC0UNT was represented, a return is made to one of the other routines or subroutines that moves XDIR to RDIR or MDIR and XDAC to RDAC or MDAC.

FIG. 27 shows the MASS subroutine. This MASS subroutine creates a variable RESULT for generating an output signal. The program is block 1
At 158, the MASS subroutine is entered. At block 1160, the current measurement count signal MDAC is collected and the MDAC is connected to the D/A along line 494.
It is sent to converter 130. At block 1162,
The value of DFAC is moved to FAC. DFAC is a dummy variable that is normally 1. FAC is used by the MASS subroutine as a multiplier to change the value of MDAC. The value specified for FAC is the value of DFAC if temperature compensation is not requested, and the value of TFAC if temperature compensation is requested. At block 1164, it is determined whether bit 5 of MODE has been set. If bit 5 is set, the program executes the temperature compensation branch 1165 of the MASS subroutine.
to go into. At block 1166, the output of temperature sensor 1020 is read. The value of TEMP must be between 00 (hexadecimal) and FF (hexadecimal). However, if TEMP is equal to either 0O or FF, an overtemperature or undertemperature condition exists. Therefore, at block 1168, TEMP
It is determined whether the value is equal to 00 (hexadecimal) or FF (hexadecimal). TEMP is 00 (hexadecimal) or FF
(hex), the program will block 1
170 and 5NAFU is set to indicate that a temperature error has occurred. If TEMP is within its proper range, the program returns to block 1172.
is executed and a one-dimensional temperature table is accessed using the value of TEMP. The temperature table input corresponding to TEMP is transferred to TFAC. At block 1174,
The value of TFAC is moved to FAC and the 5NAFU is cleared to indicate that the previously occurring temperature error no longer exists.

At block 1176, the value of bit 6 of MODE is determined. If bit 6 is set, block 1
At 178, the value of FAC is doubled and the resolution of temperature compensation branch 1165 is doubled. If bit 6 is reset, doubling the resolution is not required and block 1178 is not executed. Block 1180
Now, using FAC, the magnitude of the measurement count signal is changed by multiplying the value of FAC by the value of MDAC and moving the result to RESULT. If temperature compensation was not required, MDAC has been multiplied by DFAC. If temperature compensation was not requested, the MDA
C is multiplied by TFAC. At block 1182, it is determined whether the value of RESULT is small enough for flow meter 10 to indicate zero flow, as discussed in more detail below.

At block 1184, the value of RESULT is PIA10
24, which generates an output signal that is sent along line 1022 to output interface 537 and determines the split flow rate for each binary flow multiplier in interface 537. The program is block 11
The MASS subroutine is exited at 86.

FIG. 28 shows the ZERO subroutine. This ZERO subroutine performs the necessary preliminary steps to establish a new zero flow offset by establishing a new value for RCOUNT. especially,
In the ZERO subroutine, MC0U for the time
By changing RCOUNT so that the average value of NT is closer to zero than under zero flow conditions, RC
A rough adjustment is made to OUNT.

Generally, under zero flow conditions, non-zero measurement count signals are typically accumulated due to the presence of mechanical noise in the flow meter. Since mechanical noise changes over time, the count offset is not constant. Therefore,
The ZERO subroutine can be thought of as a rough adjustment that reduces the change over time from zero MC0UNT. The AVE subroutine, described in detail below, can be thought of as a fine-tuning that changes RCOUNT so that the time average value of MC0UNT is closer to zero. In particular, in the ZERO subroutine, during execution of this ZERO subroutine, RCOUNT is changed until the program determines whether MC0UNT is equal to zero (meaning that RCOUNT then represents an actual zero flow offset). . If the zero flow offset remains constant, no further adjustment of RCOUNT is necessary. However, the mechanical noise that causes the zero flow offset varies significantly, so MC0UN
T is rarely equal to zero and MC0UN
It is believed that T is almost non-zero. Therefore, A.V.
In the E subroutine, RCOUNT is changed over time to force the average value of MC0UNT to be very close to zero.

The program enters the ZERO subroutine via block 1188. At block 1190.

It is determined whether T is equal to 255. T is.

This is a variable used by the ZERO subroutine as a timer. When microprocessor 1000 receives a new request to calculate a zero flow offset, the program waits a delay time equal to the time required for the program to repeat the MAIN routine and ZERO subroutine 255 times.

This delay time is required to allow flow meter 10 to mechanically stabilize. I mean.

This is because the flow meter 10 includes a device that mechanically forces a zero flow condition into existence as a condition to enable a new calculation of the zero flow offset. Therefore,
If T is not equal to 255, the stabilization delay time has not elapsed, T is incremented by one at block 1192, and the program returns to the main routine via block 1194. If T is equal to 255, the program sets the MAIN routine and ZERO routine to 255.
Repeat twice, the delay time is over and the program is in block 1
Proceed to 196. At block 1196, it is determined whether MC0UNT is equal to zero.

If MC0UNT is equal to zero, the value of RCOUNT represents the zero flow offset of flow meter 10 at that time. Therefore, a rough measurement of RCOUNT has been made and block 1198 sets AVE and MAIN
The next time the routine is executed, the program moves to the AVE subroutine and fine adjustments to RCOUNT are made. At block 1200, J, N, and AVG are set to zero; all three are used in the AVE subroutine and must be equal to zero when the AVE subroutine is first entered. If MC0UNT is not equal to zero, then the coarse adjustment of RCOUNT is not complete and the program proceeds to block 1202. At block 1202, it is determined whether MC0UNT is greater than zero.

If M COU N T is greater than zero, then MC0
UNT is too large and RCOUNT must be decreased so that MC0UNT approaches zero.

Therefore, at block 1204, RCOUNT is decremented by one. If MC0UNT is less than or equal to zero,
MC0UNT is too small and RCOUNT must be increased to bring MC:0UNT closer to zero. Therefore, at block 1206, RCOUNT is incremented by one. At block 1208, the value of RCOUNT is moved to X, COUNT, allowing the new value of RDAC to be sent to D/A converter 116 and
The new value of DIR can be sent to direction controller 128. At block 1210, the program transitions to the absolute value subroutine where the magnitude of the zero flow offset represented by RCOUNT is moved to XDAC and the sign of the offset represented by RCOUNT is moved to XDIR. At block 1212, the XDA
The value of C is moved to RDAC and the value of XDIR is moved to RDIR, allowing these new values to be provided to D/A converter 116 and direction controller 128. The program then exits the ZERO subroutine at block 1194.

FIG. 29 shows the AVE subroutine. AVE
The subroutine makes fine adjustments to RCOUNT by adjusting RCOUNT to force the average value to zero when calculating the average value by averaging the 128 consecutive values of MC0UNT. The program enters the AVE subroutine at block 1206. At block 1208, the value of AVG is increased by the current value of MC0UNT. At block 1210, the value of N is increased by one. The variable N is used to determine how many times AVG is incremented by MCOUNT. Block 121
2, it is determined whether N is equal to 128. If N is not equal to 128, then a complete averaging operation has not been performed and the program returns A at block 1214.
Exit the VE subroutine and return to the MAIN routine and read MC0UNT as directed by phase comparator 118.
increase and decrease. If N is equal to 128, then 1
Two averaging operations have been completed and AVG is MC0UNT.
contains a value equal to the sum of the 128 previous values of . At block 1216.

The value of AVG is determined. If AVG is equal to zero, fine tuning of RCOUNT is complete and now RC
The value of OUNT accurately represents the zero flow offset of flow meter 10. At block 1218, 5NAFU is cleared, indicating that the calculation of RCOUNT is complete.

Block 1218 also clears ZERO and AVE, causing the program to execute neither the ZERO nor the AVE subroutines, but to execute the MASS subroutine the next time the MAIN subroutine is entered. At block 1220, the RCOUNTE PROM designated to store the value of RCOUNT is loaded.
A new value of COUNT is written. block 121
If it is determined at block 1222 that AVG is not equal to zero, then the averaging operation did not yield enough values for RCOUNT, and AVG is determined at block 1222 to
is greater than zero. If AVG is greater than zero, the value of MC0UNT is still too large;
RCOUNT is decreased to force the value of MCOUNT and AVG calculated during the next averaging operation toward zero. If AVG is less than or equal to zero, MC0UN
The value of T is too low and in block 1226 MC0UN
RCOUNT is increased so that T and the average value of MC0UNT over time approach zero. At block 1228, the value of RCOUNT is moved to XC0UNT, and the program is ready to execute the absolute value subroutine to which it enters at block 1230. In the absolute value subroutine, the value representing the current sign of RCOUNT is
DIR and the current size represented by RCOUNT is moved to XDAC. At block 1232, XDIR is moved to RDIR, XDAC is moved to RDAC, and the appropriate signals for the latched count signal are sent to D/A converter 116 and direction controller 128. At block 1232, J is incremented by one. J is used to count the number of averaging operations performed by the AVE subroutine.
A variable used by a subroutine. At block 1234, it is determined whether J is equal to 32.

If J is equal to 32, then 32 averaging operations have been performed on the AVG without producing a value of zero.

Here, it is assumed that AVG is not equal to zero, but that the value of MC0UNT associated with the original time of zero flow conditions is close enough to zero to warrant performing further averaging operations. Therefore, the program moves to block 1218. If J is not equal to 32, another averaging operation is performed by the AVE subroutine. At block 1236, the state of 5NAFU is changed to indicate that the new value of RCOUNT is still in effect. Therefore, if the signal on line 1016 changes periodically between high and low levels, it can be assumed that the flow meter is still calculating a new zero flow offset. Also, at block 1236, N and A
VG is zeroed and variables for the next averaging operation are initialized. The program exits the AVE subroutine through block 1214.

FIG. 30 shows the CUTOFF subroutine. Generally, this cutoff subroutine determines whether the value of RESULT is below a threshold level, and thus low enough that meter 10 should output a zero mass flow rate. The cutoff subroutine can use any of three threshold levels. Each threshold level is (n/4095)fsr, where fsr is the full-scale range of the system.

Bits 0 and 1 of MODE indicate whether the program should use a cutoff routine and, if so, specify the threshold level as follows.

Value of bit O11 Tongue: Lower - ○, O Cutoff subroutine not required 0.1 Cutoff subroutine required threshold level is (64/4095) X fsr 1.0 Cutoff subroutine required threshold level is (128/4095) Xfsr 1.1 Cutoff Subroutine Required Threshold Level is (192/4095) The Xfsr program enters the cutoff subroutine at block 1238. At block 1240, MODE
It is determined whether bits O and 1 of are both 0.

If bits O and 1 are both O, then the cutoff subroutine is not required and the program returns to 124
The cutoff subroutine is exited at 2. If bits 0 and 1 are both non-zero, block 1244.
At 1250 and 1254 their values are determined. If bit O is O and bit 1 is 1, then
The threshold level is 64/4095fsr, and block 1244 causes the program to block 12
Moving to 46, it is determined whether RESULT is less than 40 (hexadecimal). If RESULT is less than 40 (hexadecimal), then the value of RESULT is less than the threshold level and the RE
0 is sent to SULT. If bit 0 is 1 and bit 1 is O, then the threshold level is (
128/4095) fsr, and at block 1250 the program moves to block 1252 and the RES
It is determined whether ULT is less than 80 (hexadecimal);
If so, in block 1248 RESUL
0 is specified for T. If the value of RESULT is greater than or equal to 80 (hexadecimal), the program returns to the MASS subroutine. If bits 0 and 1 are both 1, the threshold level is (192/4095
) f s r and block 1254 transfers the program to block 1256 where RESULT is Co
(hexadecimal). RESUL
If T is less than Co (hex), RESUL
T is below the threshold level, block 12
48 moves O to RESULT. RESULT
If is greater than or equal to Go (hexadecimal), the program returns to the MASS subroutine. If for any reason, block 1245 determines that both bits O and 1 are not 1, the program returns the cant-off subroutine.
exit and return to the MASS subroutine.

[Brief explanation of drawings]

1 is a side view of a sensing assembly constructed in accordance with a preferred embodiment of the present invention, with the central body partially cut away; FIG. 2 is a side view of the sensing assembly of FIG. Front view of the solid. 3 is a bottom view of the sensing assembly of FIG. 1, FIG. 4 is a sectional view of the sensing assembly of FIG. 1 taken along line rV-rV, and FIG. 5 is a bottom view of the sensing assembly of FIG. 2. 6 is a sectional view of the sensing assembly shown in FIG. 2 taken along line VI-VI; FIG. 7 is a sectional view of the assembly shown in FIG. 8 is a to-scale drawing of the assembly shown in FIG. 1; FIG. 9 is a block diagram of a preferred signal processing system according to the present invention; FIG. Graphs illustrating the periodic and threshold signals received by the accuracy comparator and the comparison signals generated by the comparator, FIGS. 11-15, are particularly useful for implementing the system of FIG. Schematic diagram showing useful circuit details; Figure 16 is a detailed complete circuit diagram of the LVDTIS @ dynamic circuit; Figure 17 is a diagram showing details of the LVDT demodulator; Figure 18 is a vibrating mass flow meter. FIG. 19 is a diagram illustrating a pair of voltage comparators used in the known time difference technique. FIG. 20 shows a threshold signal generated by a known system using one time difference technique and a periodic electrical signal generated by one position sensor;
9, FIGS. 21-30 illustrate the signals generated by the voltage comparator of FIG.
FIG. 31 shows the portion of the system that includes microprocessor 1000, and FIG. 32 is a block diagram of microprocessor 1000. 10... Sensing assembly 11... Central body 12...
Conduit 14.33 Inlet 16.35 Outlet 18.20 Conduit section 22.24 Manifold section 15.19 Flange 26 Conduit drive assembly 27 ... Case 28.30 ... Speed sensor 37.43 ... Isolator 48 ... Permanent magnet 54 ... Coil 66.68
...Housing 70.72.74.76...Housing 100...
Signal processing system 104... Conduit drive circuit 106... Automatic gain controller 108... Switched capacitor integrator 110.11
1...Peak detector 112...Auto zero circuit 114.126...High precision comparator 116.130...D/A converter 118...Phase comparator 128.134...Direction controller 120...Digital counter 122...-ROM 124...Feedback control system 130...
D/A converter 132...Latch 134...Direction controller drawing: (No change in hole capacity) FIG. 2
FIG, 3FIG, 4 FIG, 8 FIG, old FIG, 19 FIG, 20 Procedural amendment (method) 61.11.271. Indication of the case Patent Application No. 131688 of 1985 2, Title of the invention Mass flow meter and its signal processing system 3, Person making the amendment Relationship to the case Applicant

Claims (20)

[Claims] (1) In a system that provides an indication of the phase difference that exists between two periodic electrical signals, a measurement comparison signal is generated from the first signal of the periodic electrical signals, and a measurement threshold signal is also generated. the phase difference between the measurement comparison signal and the first periodic signal is based on the level of the measurement threshold signal with respect to the first periodic signal; means for generating a measured characteristic signal related to a peak amplitude of the periodic signal; and means for generating a command signal, the nature of the command signal being such that the measured comparison signal is derived from a second of the periodic signals. and further comprising means for accumulating a count signal, said command signal determining when the level of said count signal is increased and decreased; Further, means is provided for generating the measurement threshold signal by combining a signal corresponding to the count signal and the measurement characteristic signal, whereby the count signal exists between the periodic electrical signals. A system characterized by giving instructions on phase difference. (2) The reference signal is a reference comparison signal, and the generating means generates the reference comparison signal from the second periodic electric signal and also generates a reference threshold signal, and the phase difference with the second periodic signal is based on the level of the reference threshold signal with respect to the second periodic signal; The characteristics of the command signal generated by the command signal generating means are as follows:
The measurement comparison signal is based on whether the measurement comparison signal leads or lags the reference comparison signal, and the synthesis means synthesizes the reference characteristic signal and the signal derived from the count signal to obtain the reference threshold. A system as claimed in claim 1 for generating a hold signal. (3) In a system that provides an indication of the phase difference that exists between two periodic electrical signals, a measurement comparison signal is generated from the first signal of the periodic electrical signals, and a measurement threshold signal is also generated. the phase difference between the measurement comparison signal and the first periodic signal is based on the level of the measurement threshold signal with respect to the first periodic signal; means for generating a measurement characteristic signal related to the peak amplitude of the periodic signal; and means for generating a command signal, the nature of which the command signal is such that the measurement comparison signal leads a fixed phase reference signal. and further comprising means for accumulating a count signal, said command signal determining when the level of said count signal is increased and decreased, and further comprising means for accumulating said count signal; means for combining a corresponding signal with the measurement characteristic signal to generate the measurement threshold signal, such that the count signal provides an indication of the phase difference that exists between the periodic electrical signals; A system characterized by the following. (4) In a system that provides an indication of the phase difference that exists between two periodic electrical signals, a measurement comparison signal is generated from a first signal of the periodic electrical signals, and a measurement threshold signal is also generated. means for determining, wherein the phase difference between the measurement comparison signal and the first periodic signal is based on a level of a measurement threshold signal with respect to the first periodic signal;
Further, the means generates a reference comparison signal from a second of the periodic electrical signals and also generates a reference threshold signal, wherein the phase difference between the reference comparison signal and the second periodic signal is means adapted to be based on the level of a reference threshold signal for a second periodic signal, further comprising means for generating a measurement characteristic signal related to a peak amplitude of said first periodic signal; means for generating a reference characteristic signal related to the peak amplitude of the second periodic signal; further comprising means for generating a command signal, the nature of the command signal being based on whether the signal is leading or lagging the reference comparison signal, and further comprising means for accumulating a count signal, the command signal determining when the level of the count signal is increased and decreased. Further, a signal corresponding to the count signal and the measurement characteristic signal are combined to form the measurement threshold signal, and a signal derived from the count signal and the reference characteristic signal are combined to form the measurement threshold signal. A system comprising: means for generating a reference threshold signal, whereby said count signal provides an indication of the phase difference that exists between said periodic electrical signals. 5. The system of claim 4, further comprising means for maintaining a fixed phase difference between the reference comparison signal and the second periodic electrical signal. (6) A system for providing an indication of the phase difference existing between two periodic electrical signals, comprising a pair of comparators receiving said two periodic signals, each of said comparators each comparator receives as its input said periodic electrical signal and analog threshold signal associated with it, said comparator generates a periodic comparison signal, and said comparison signal and said analog threshold signal. the phase difference with the corresponding periodic electrical signal is based on the level of the threshold signal, and further comprising a peak detector associated with each periodic electrical signal, each peak detector having: receiving as its input a periodic electrical signal associated therewith, the peak detector generates a peak signal representative of the peak level of each half cycle of the periodic electrical signal associated therewith; associated D/A converters, each D/A converter receiving as its inputs the peak signal generated by its associated peak detector and the digital signal, the D/A converter comprising:
further comprising a phase comparator for multiplying the peak signal by the digital signal to generate the threshold signal for the comparator, and receiving as input the comparison signal generated by the comparator, the phase comparator The device generates a series of command signals that are
It is of the first type if, at its occurrence, a first said comparison signal leads a second said comparison signal, and if said first comparison signal lags the second said comparison signal. of a second type, further comprising means for accumulating a count signal, the accumulating means increasing said count signal when receiving a command signal of said first type; the count signal is decreased when a command signal of the form A system characterized in that it provides an indication of the phase difference that exists between signals. (7) further comprising a latch receiving the count signal as an input, the latch generating a latched count signal, the latched count signal being digital when the latch receives the first type of command; 0
and the latched count signal is the value of the count signal present at the input of the latch when the latch receives a second type of command; 7. The system of claim 6, wherein the digital signal is sent to a /A converter as said digital signal. (8) a conduit attached to a support at each end; means for vibrating the conduit; and means for generating a pair of periodic electrical signals representative of the motion characteristics of the conduit at two predetermined points; a system for providing an indication of the phase difference that exists between periodic electrical signals, the system comprising: generating a measurement comparison signal from a first of the periodic electrical signals; means for generating a measurement threshold signal, the phase difference between the measurement comparison signal and the first periodic signal being based on the level of the measurement threshold signal relative to the first periodic signal; further comprising means for generating a measurement characteristic signal related to the peak amplitude of the first periodic signal; and means for generating a command signal, the nature of the command signal being such that the measurement comparison signal The command signal is based on whether the periodic signal leads or lags a reference signal derived from the periodic signal, and further comprises means for accumulating a count signal, and the command signal is configured to increase and decrease the level of the count signal. further comprising means for generating the measurement threshold signal by combining a signal corresponding to the count signal with the measurement characteristic signal, whereby the count signal A mass flowmeter characterized in that an indication of a phase difference existing between signals and an indication of a mass flow rate of an object flowing through the conduit are given. (9) a conduit attached to a support at each end; means for vibrating said conduit; and means for generating a pair of periodic electrical signals representative of the motion characteristics of said conduit at two predetermined points; a system for providing an indication of the phase difference that exists between periodic electrical signals, the system comprising: generating a measurement comparison signal from a first of the periodic electrical signals; means for generating a measurement threshold signal, the phase difference between the measurement comparison signal and the first periodic signal being based on the level of the measurement threshold signal relative to the first periodic signal; further comprising means for generating a measurement characteristic signal related to the peak amplitude of said first periodic signal, and means for generating a command signal, the nature of said command signal being such that said measurement comparison signal is of a fixed phase. based on being ahead or behind a reference signal, further comprising means for accumulating a count signal, said command signal determining when the level of said count signal is increased and decreased; , comprising means for combining a signal corresponding to the count signal and the measurement characteristic signal to generate the measurement threshold signal, whereby the count signal is controlled by the phase difference that exists between the periodic electrical signals. and an indication of the mass flow rate of an object flowing through the conduit. (10) a conduit attached to a support at both ends; means for vibrating the conduit; and means for generating a pair of periodic electrical signals representative of the motion characteristics of the conduit at two predetermined points; a system for providing an indication of the phase difference that exists between periodic electrical signals, said system comprising a pair of comparators, each of said comparators having an indication of the phase difference that exists between said electrical signals; Associatedly, each comparator receives as its input said periodic electrical signal and said analog threshold signal associated with it, said comparator generating a periodic comparison signal, said comparison signal and said corresponding periodic signal. the phase difference with the periodic electrical signal is based on the level of the threshold signal; Receiving as its input a periodic electrical signal, the peak detector generates a peak signal representative of the peak level of each half cycle of the periodic electrical signal associated therewith; /A converter, each D/A converter receiving as its input the peak signal generated by its associated peak detector and the digital signal, the D/A converter comprising:
further comprising a phase comparator for multiplying the peak signal by the digital signal to generate the threshold signal for the comparator, and receiving as input the comparison signal generated by the comparator, the phase comparator The device generates a series of command signals that are
It is of the first type if, at its occurrence, a first said comparison signal leads a second said comparison signal, and if said first comparison signal lags the second said comparison signal. of a second type, further comprising means for accumulating a count signal, the accumulating means increasing said count signal when receiving a command signal of said first type; the count signal is decreased when a command signal of the form A mass flowmeter characterized in that it provides an indication of the phase difference that exists between the signals and an indication of the flow rate of an object flowing through the conduit. (11) a conduit attached to a support at both ends; means for vibrating the conduit; and means for generating a pair of periodic electrical signals representative of the motion characteristics of the conduit at two predetermined points; a system for providing an indication of a phase difference that exists between periodic electrical signals, the system receiving the periodic signals and corresponding to a first of the periodic electrical signals. means for generating at least one periodic comparison signal, and further comprising means for generating at least one periodic comparison signal, and further comprising means for generating a command signal by comparing said periodic comparison signal with a periodic reference signal derived from a second said periodic electrical signal. the nature of the command signal is based on the spatial relationship that exists between the comparison signal and the reference signal, further comprising means for accumulating a phase signal in response to receiving the command signal. , the accumulating means changes the phase signal based on the nature of the command signal, and the comparison signal generating means generates a predetermined gap between the comparison signal and the reference signal when the phase signal is changed. reducing the phase difference between the reference signal and the comparison signal until a spatial relationship is established, such that when the predetermined spatial relationship is established, the phase signal is present between the periodic electrical signals. A mass flowmeter characterized in that it gives an indication of a phase difference. (12) a conduit attached to a support at each end; means for vibrating the conduit; and means for generating a pair of periodic electrical signals representative of the motion characteristics of the conduit at two predetermined points; a system for providing an indication of a phase difference that exists between periodic electrical signals, the system receiving the periodic signals and corresponding to a first of the periodic electrical signals. means for generating at least one periodic comparison signal; further comprising means for comparing the periodic comparison signal with a fixed phase periodic reference signal to generate a command signal; the nature of the signal is based on the spatial relationship that exists between the comparison signal and the reference signal, and further comprising means for accumulating a phase signal in response to receiving the command signal; The accumulating means modifies the phase signal based on a property of the command signal, and the comparison signal generating means establishes a predetermined spatial relationship between the comparison signal and the reference signal when the phase signal is modified. reducing the phase difference between the reference signal and the comparison signal until the predetermined spatial relationship is established, such that the phase signal is an indication of the phase difference that exists between the periodic electrical signals; A mass flowmeter characterized in that it gives. (13) a support and a conduit, a first portion of the conduit defining an inlet and an outlet connected to the support; and a second portion of the conduit connected to the support. A third portion of the conduit defines an outlet and an inlet.
an outlet of the first section is joined to an inlet of the second section, the conduit forming a bend in a first direction at the junction of the outlet of the first section and the third section; forming a bend in a second direction at the junction of a third portion and an inlet of the second portion, and further vibrating the conduit in a direction transverse to the longitudinal axis of the third portion to providing an increasing gradient of lateral velocity of flowing material between the inlet of the conduit and the outlet of the first section, thereby imparting a lateral force gradient on the conduit in a first direction; vibrating means for imparting a decreasing gradient in the lateral velocity of the flowing material between the conduit and the outlet of the second portion, and thus imparting a transverse force gradient on the conduit in a second direction; , comprising means for sensing the mechanical effect of the force gradient on the conduit to form a pair of periodic signals related to the mass flow rate of material flowing therefrom into the conduit;
A mass flow meter comprising a system for providing an indication of a phase difference between the pair of periodic electrical signals, the system receiving the periodic signals and corresponding to a first of the periodic electrical signals. means for generating at least one periodic comparison signal, and further comprising means for generating at least one periodic comparison signal, the periodic comparison signal being compared to a periodic reference signal derived from a second periodic electrical signal to generate a command signal. means for generating a command signal, the nature of the command signal being based on the spatial relationship that exists between the comparison signal and the reference signal, and further comprising means for accumulating a phase signal in response to receiving the command signal. means for modifying the phase signal based on the nature of the command signal; and the comparison signal generating means is configured to detect a difference between the comparison signal and the reference signal when the phase signal is modified. reducing the phase difference between the reference signal and the comparison signal until a predetermined spatial relationship is established, such that when the predetermined spatial relationship is established, the phase signal is between the periodic electrical signals; A flow meter characterized in that it gives an indication of the phase difference present. (14) The system according to claim 1, wherein the reference signal is the second periodic signal. (15) comprising a support and a conduit, the first introduction portion of the conduit having an inlet connected to the support;
a second discharge portion of the conduit defining an outlet connected to the support and an inlet; a third portion of the conduit connecting the outlet of the first portion to the second portion; the conduit includes a first bend at the junction of the first portion and the third portion, which bends fluid flowing through the conduit in a first direction. further forming a second bend at the junction of the third portion and the second portion, which bends the fluid in a different direction; The three sections are vibrated in a direction transverse to their longitudinal axes to provide an increasing gradient of lateral velocity of the flowing material between the first section inlet and the first section outlet, thereby increasing the lateral velocity of the conduit. imparting a force gradient in a first direction and a decreasing gradient in the lateral velocity of material flowing between the inlet of the second section and the outlet of the second section, thereby imparting a lateral force gradient in the conduit; in a second direction, further comprising means for generating a pair of electrical signals related to the magnitude of the force exerted on the conduit by the lateral force gradient; A mass flow meter comprising a system for providing an indication of a phase difference between the periodic electrical signals, the system receiving the periodic signals and generating a comparison signal from at least a first of the periodic electrical signals. means for shifting the comparison signal such that a phase difference between the comparison signal and a reference signal corresponding to the second periodic electric signal is reduced to a predetermined magnitude; and means for shifting the comparison signal. means for monitoring and accumulating the angle at which the comparison signal and the reference signal reduce the phase difference to the predetermined magnitude; A mass flow meter, wherein the accumulated angle provides an indication of the phase difference between the periodic electrical signals when . (16) a support and a conduit defining an inlet and an outlet, the inlet and outlet being attached to the support, and the conduit being connected to a line connecting the locations where it is attached to the support; and further vibrating the conduit transversely to the longitudinal axis of the third section to create a gradient of increasing transverse velocity of material flowing between the inlet of the first section and the outlet of the first section. imparting, and thus imparting a lateral force gradient to the conduit in a first direction and a decreasing gradient of lateral velocity of material flowing between an inlet of the second portion and an outlet of the second portion; a pair of electrical signals related to the magnitude of the force exerted on the conduit by the lateral force gradient; and further comprising a system for providing an indication of a phase difference between the periodic electrical signals, the system receiving the periodic signals and providing an indication of the phase difference between the periodic electrical signals; means for generating a comparison signal from a periodic electrical signal; means for shifting the comparison signal to reduce a phase difference between the comparison signal and a fixed phase reference signal to a predetermined magnitude; means for monitoring and accumulating shifting angles to reduce the phase difference to the predetermined magnitude, thereby reducing the phase difference between the comparison signal and the reference signal to the predetermined magnitude. 2. A mass flow meter, wherein the accumulated angle provides an indication of the phase difference between the periodic electrical signals when the angle is reached. (17) The mass flowmeter according to claim 8, wherein the reference signal is the second periodic electric signal. (18) a conduit attached to a support at each end; means for vibrating the conduit; and means for generating a pair of periodic electrical signals representative of the motion characteristics of the conduit at two predetermined points; a system for providing an indication of a phase difference that exists between periodic electrical signals, the system receiving the periodic signals and making a comparison from at least a first of the periodic electrical signals. means for generating a signal; means for shifting the comparison signal to reduce a phase difference between the comparison signal and a reference signal corresponding to a second periodic electrical signal to a predetermined magnitude; and means for shifting the comparison signal to a predetermined magnitude. means for monitoring and accumulating angles of shifting of the reference signal to reduce the phase difference to the predetermined magnitude, thereby reducing the phase difference between the comparison signal and the reference signal to the predetermined magnitude. A mass flow meter characterized in that, when a magnitude is reached, said accumulated angle provides an indication of the phase difference between said periodic electrical signals. (19) a conduit attached to a support at both ends; means for vibrating the conduit; and means for generating a pair of periodic electrical signals representative of the motion characteristics of the conduit at two predetermined points; a system for providing an indication of a phase difference that exists between periodic electrical signals, the system receiving the periodic signals and making a comparison from at least a first of the periodic electrical signals. means for generating a signal; means for shifting the comparison signal to reduce a phase difference between the comparison signal and a fixed phase reference signal to a predetermined magnitude; and monitoring and accumulating the angle by which the comparison signal is shifted. and means for reducing the phase difference to the predetermined magnitude, whereby when the phase difference between the comparison signal and the reference signal reaches the predetermined magnitude, the A mass flow meter characterized in that the accumulated angle provides an indication of the phase difference between the periodic electrical signals. (20) The mass flowmeter according to claim 18, wherein the reference signal is the second periodic electrical signal.