GB2143642A - Tachograph with multifunction recording stylus - Google Patents

Abstract

A tachograph includes means for imparting at least two distinguishable forms of movement (representing different data inputs respectively) to the same recording stylus. One form of movement may produce a conventional odometer zig-zag trace 2, whilst the other causes the stylus to draw a multiplicity of oscillating or pulsating lines 1, at a high frequency, on one side of the zig-zag trace. The amplitude or frequency of the high frequency component, or both, may be varied, preferably in steps, to designate variations in the additional function or functions to be recorded. The zig-zag motion may be produced by a heart-shaped cam 9, and the high frequency lines by a solenoid armature 14 biassed by a spring 15, both the cam 9 and the armature 14 acting on the stylus 7 via a lost motion linkage 10,13,17. Alternatively, the stylus may be coupled to a program-controlled stepper motor. <IMAGE>

Description

SPECIFICATION Tachograph with multifunction recording stylus This invention relates to tachographs. Tachographs are instruments which are normally fitted to commercial vehicles in order to record data relating to duties performed by a driver (such as driving the vehicle, resting and carrying out active work other than driving) and data relating to the speed and distance covered by the vehicle. It may be essential, in accordance with the respective legal requirements of the country concerned, to record such data when a commercial vehicle is used.

Such data will be generally referred to herein as 'legal data'.

Conventional tachographs have a generally standard type of construction (like a large speedometer) which facilitates installation in a vehicle.

They normally incorporate a speedometer and a clock, and they usually comprise a housing with a hinged transparent cover through which can be seen the speedometer markings, the speed indicating needle, the dial and hands of the clock and, in some cases, a portion of the recording face of a circular chart. The housing contains a motor-driven turntable on which the chart is supported so that it rotates once in 12 or 24 hours. Usually, a plurality of recording pens or styli are mounted within the casing and are coupled to respective linkages or other devices to convert the respective mechanical inputs which need to be recorded, into suitable outputs for driving the respective styli.For example, a control knob, normally fitted to the front of the housing and which can be rotated, by the driver, into any one of four different positions each representing a different duty, is usually connected by a linkage to the respective stylus whereby a trace is recorded on the chart, within a certain annular band, to signify which duty has been selected at various times throughout the 12 to 24 hour recording. The driver duty is normally recorded in a trace which shows a series of steps extending circumferentially around the chart.

However, in order to avoid using such a linkage, it has been proposed to employ a stepper motor which is remotely controlled by the control knob whereby the respective stylus, which is dedicated to recording driver duty, periodically draws a radial line (i.e. with respect to the circumferential time axis). The recording has the appearance of a series of vertical and separately spaced lines, each line having any one of three or four different lengths, the line length representing the selected driver duty. As driver duties are normally carried out over certain periods of time, the recording trace normally looks like a series of shaded blocks of different heights. Although different duties are involved in recording such a trace, it will be understood that the particular way in which the stylus moves represents only one kind of data input.

In the case of recording the speed or distance covered by a vehicle, the styli dedicated to recording these functions are connected to linkages or mechanisms which respond to signals derived from suitable transducers for converting, e.g. rotary mechanical inputs, such as the input derived from a speedometer shaft, into suitable outputs.

In the development of the tachograph, it has become of increasingly greater interest to the users to have the facility for recording parameters additional to those relating to the legal data mentioned above.

For example, in certain countries it is (or will become) necessary for a tachograph to provide a recording of when a vehicle engine is running, or when it has been switched off (i.e. this is additional 'legal data'). From a more general point of view, since an onboard recording device is provided in a vehicle when tachographs are required by iaw, the tachograph can be used to record parameters such as fuel consumption, engine shaft revolutions per minute, trailer coupling and uncoupling, etc. Such parameters are of interest to fleet owners, for example, to check vehicle performance and usage and to encourage the drivers to operate their vehicles more carefully and hence more economically.

Yet again in other areas, there are specialised requirements for data such as that indicating when a siren or flashing light has been switched on or off e.g. on a police vehicle or ambulance.

In order to accommodate the recording of such additional functions, tachographs have been made with an additional stylus or styli. However, this creates various problems. One such problem is an increase in the complexity of the mechanism and the difficulty of manufacturing and installing the same within the confined space of the (speedometertype) housing of the tachograph. Another more serious problem arises due to the com paratively small shape and size (diameter) of the chart and the generally standard layout of the annular recording tracks. In view of the amount of information which needs to be recorded on such charts, the annular recording space is at a premium and certain annular bands are normally always used to record particular functions.There is thus a severe problem of finding enough space for the recording of an additional trace relating to a function or functions other than those associated with say the legal data mentioned above. In some cases, there may be no room on the chart for an additional recording trace. In other cases, it may be necessary to squeeze the annular recording bands into an even more confined space (to enable an additional trace to be recorded) and this clearly impairs the readability of the recordings besides giving rise to all kinds of manufacturing problems. Thus, the provision of an additional stylus does not offer a practical solution to the problem.

An alternative solution may be to employ a scanning stylus, i.e. one which continually scans across the annular recording tracks of the chart and which is caused briefly to touch the chart, in the respective track, to make a mark representing an instantaneous value of the function to be recorded in that track. However, such a scanning stylus is not a practical solution due to factors such as expense, installation of the necessary mechanism within the confined space of the (speedometer) housing, and the non-standard nature of a recording made by such a stylus on the chart.

The present invention seeks to provide a solution to the problems mentioned above without the need for an additional recording stylus and without affecting the standard form of recording or its quality.

The invention achieves this object by providing means for imparting at least two distinguishable forms of movement to the same recording stylus, which forms of movement respectively represent different data inputs.

For example, in a preferred embodiment of the invention, the stylus which records the output of an odometer, normally by drawing a zig-zag track (each zig and zag representing a fixed distance travelled by the vehicle), is also caused to oscillate, vibrate or pulsate at a high frequency to provide a visible indication of another function or functions.

This additional oscillation or pulsation of the stylus at high frequency causes the stylus to draw what appear to be blocks of shaded lines which are easily distinguishable from the zig-zag pattern of the odometer recording. The amplitude of the high frequency oscillation or pulsation may be varied preferably in the predetermined steps, to designate the change in, or variation of, an additional function or functions. For example, a function to be recorded may be either an event (such as the operation or not of an engine, or siren), or it may relate to a variable quantity from which certain predetermined values are derived (such as high, normal and low engine speed or rpm).

In the case of adding a distinguishable movement to a conventional odometer zig-zag trace, it is preferred to impart a high frequency component to the stylus in such a way that the high frequency movement (or lines of shading) appear on only one side of the zig-zag trace. The additional function or functions do not then interfere with, or obscure, the crests and troughs of the zig-zag.

However, other arrangements are possible.

More generally speaking, in a tachograph in accordance with the invention, at least one stylus is coupled to means for imparting a first transverse motion which represents a first data input, and for imparting at least a second data input, said motions of the stylus being transverse to the direction of motion of the chart with respect to time.

The first transverse motion may be such as to provide a discernible step, saw tooth or sinusoidal function. The second transverse motion may be such as to repre sent a discernible pulsation or oscillation at a relatively higher frequency. The amplitude, or the frequency of the pulsation or oscillation, or both, may be varied in accordance with an additional function or functions to be recorded on the chart. Means may be suitably provided for deriving signals representing events or predetermined values of a respective function, which signals are either used directly, or processed to provide a suitable drive for the stylus.

As mentioned above, an odometer zig-zag trace may have a high frequency component impressed on one side of the sawtooth waveform and the amplitude of the high frequency component may vary in steps on one side of the zig-zag trace. (The presence or absence of the high frequency component may also designate a function). Such an effect may be achieved, for example, by driving the stylus by means of a conventional heart-shaped cam to provide the odometer zig-zag trace, and by imparting a high frequency oscillating component (the amplitude of which may be varied in steps) to the same stylus. To prevent the high frequency component trace from overlapping the zig-zag trace, which could otherwise tend to obscure the odometer trace, sufficient lost motion is allowed between the stylus and the cam linkage.

Alternatively, the stylus is linked to a stepper motor which drives the stylus in accordance with a program executed by a microcomputer. The program conditions the microcomputer to control the start, extent of movement and stopping of the stylus to record the various input functions. As explained above, the amplitude, or frequency of a high frequency oscillation or pulsation, or tooth, may be controlled to designate changes in the additional function which is recorded.

Two of the most beneficial advantages of the invention are that the same basic or mass-produced tachograph can be easily modified, and that no changes at all are necessary to either the position of the styli or the layout of the recording traces on the chart, to accommodate the recording of an additional function or functions, All that is necessary is to find room to accommodate the means which include, for example, the above-mentioned solenoid or stepper motor for imparting the necessary and distinguishable forms of movement to one and the same stylus. Another advantage is that the additional function or functions can be recorded in such a way (e.g. giving the appearance of a block of shaded lines) which is easy to read optically, thereby facilitating either automatic, or semi-automatic chart analysis.Yet a further advantage is that the invention may be applied to any kind of tachograph and to any suitable stylus (except the one for recording speed) to add further recorded functions.

In a tachograph in accordance with the invention, one of the additional recorded functions may relate to high, normal and low engine shaft speed (r.p.m.). It is known to provide transducers and a microcomputer to supply outputs to a display for indicating high, normal and low engine shaft speed, such a display being independent of a tachograph. It is also known to provide a conventional tachograph with a dial marked in engine r.p.m. as well as vehicle speed (Km/hr), but such arrangements can be very confusing to a driver. However, in the case of recording high, normal and low engine r.p.m. in a tachograph according to the invention, associated indicating devices (such as LED's) may be located on the speedometer dial face of the tachograph. Besides avoiding the expense of providing and installing a separate display, the LED's on the tachograph dial indicate more readily to the driver that he should, for example, operate the gear box to change up or down to avoid falling outside acceptable upper and lower limits of engine speed. Compared with the task of watching two separate displays, or the task of distinguishing an r.p.m. reading from a vehicle speed reading on a tachograph fitted with a dual-purpose dial, (in addition to carrying a clockface),the LED arrangement makes it far easier for the driver to observe either a low or high r.p.m. display on the face of the tachograph itself and to be more really pre- pared to take appropriate action.

Embodiments of the invention will now be described with reference to the accompanying sehé- matic drawings in which: 4 Figure I represents a typical and conventional odometer zig-zag trace as recorded on a tachograph chart, Figure 2 represents a portion of the zig-zag trace shown in Figure 1 with an additional pulsating trace to indicate a further function or functions (with amplitude variation), Figure 3 illustrates the portion of the trace of Figure 2 in which the frequency of the oscillation is varied to record yet another function or functions (with variation in frequency as well as amplitude), Figure 4 represents a portion of the face of a tachograph equipped with engine speed LED indicators.

Figure 5 is a plan view of a cam and solenoid arrangement according to an embodiment of the invention, and Figure 6 is a side elevation of part of the arrangement shown in Figure 5.

Referring to Figures 1-3, the traces shown would normally be confined to annular bands or tracks which extend coaxially and circumferentially around the face of a circular tachograph chart.

However, for ease of illustration, the traces have been shown extending in a horizontal direction, which direction represents the normal time axis (t) of the tachograph chart. This time axis may be divided into 12 or 24 hour periods, the chart being rotated through one revolution within this period by a conventional drive motor.

Referring to Figure 1 which illustrates a typical odometer zig-zag trace, each zig and zag represents a fixed distance travelled (e.g. 5 kilometers) by the vehicle. The frequency of the zig-zag trace will change in accordance with the speed of the vehicle, but the limits of change are minimal within the low frequency range of the zig-zag recording.

Referring to Figure 2, a high frequency component 1 has been added to the recording trace by causing one and the same stylus to oscillate or pulsate at a high frequency. The effect of imparting a high frequency oscillation is to cause the stylus to draw a fine sawtooth waveform which extends beneath the coarse (zig-zag) sawtooth waveform 2 of the odometer trace. The effect of imparting a hf pulsation is to cause the stylus to draw a multiplicity of spikes extending from the zig-zag odometer trace (as illustrated). The presence or absence of the hf component can be used to record an event, such as whether or not the engine of the vehicle is running. The absence of the hf component is designated 3 in Figures 2 and 3.The amplitude of the hf component can be varied to provide a series of steps 4, 5 and 6, which represent either variations of one function, or of different functions (as men tioned above). The stylus 7 may be caused to oscil late or pulsate by means of a solenoid as shown in Figure 5.

As shown in Figures 5 and 6, the stylus 7 is cou pled to a heart-shaped cam by means of a link bar 10. Rotation of cam 9 about a pivot, due to the odometer drive (not shown) causes the stylus 7 to ,draw a zig-zag 2 on the chart 12 beneath. The chart i12 is advanced with time by a conventional chart drive (not shown). The stylus 7 is also coupled by a link to one end of an armature 14 within the so lenoid 8, the other end of the solenoid being con nected by a compression spring 15 to a fixed point 16. The link bar 10 has a slot 17 in the end remote from the cam 9, the stylus 7 being captive within the sFot 'except for the lost motion allowed by the length of the slot (between the stylus and the ar mature 14).An oscillating or pulsating current is applied to the solenoid 8 (via wires 18,19), whereby the armature 14 is caused to oscillate or pulsate at a predetermined frequency. The strength of the current is adjustable in steps to vary the am plitude of oscillation or pulsation of stylus 7. The spring 15 is provided, if necessary, to assist return of the armature 14 to a starting position.

The lost motion provided by slot 7 enables the stylus to oscillate or pulsate on one side of the zig zag trace 2, i.e. without affecting the drive between cam 9 and stylus 7.

alternatively (but not illustrated), the stylus 7 is coupled to a program-controlled stepper motor (as mentioned above).

Referring to Figure 3, the frequency of the hf component 1 has been varied to give yet a further recording function or functions. The frequency may be controlled in a series of steps, e.g. to provide discernible regions 20, 21, which facilitates recog nition on analy sis. The variation in the frequency component may be used independently of the vari ation n' amplitude, e.g. by imparting respective high frequency components to different styli.

Referring to Figure 4, the face 22 of a tachograph 23 includes three LED's 24-26 which, when illumi nated, respectively show yellow, green and red light. The LED's are controlled by a microprocessor (not shown), or some other electronic circuitry which provides appropriate signals in response to variation in engine speed and certain predeter mined limits of engine speed. As illustrated. LED 24 shows too low an engine speed, LED 25 shows normal engine speed and LED 26 shows too high an engine speed. The circuitry (not shown) to which the LED's 24-26 are connected, also provides an input to the means controlling th( flow ol ctir- rent to solenoid 8.Thus, the in(iie aliol1s of Il1e tED's 24-26 (i.e. the changes in eI0giI0e speed over the predetermined values of low, norlllll ,110(t ligl0) can be recorded on the chart (in tl0('- 110a1010("r dc- scribe above).

Whilst Ihe accompanying drawin!ls illllslr;llo 'in example wherein a hr cornponcnl is imparted lo stylus for recor(iinc,j ') li(,J-la(.l ocloriic:l!r tr'ic(.', it will be understood that the hf component could alternatively be imparted to a different stylus (such as that used for recording the change of driver dutywhich normally draws a stepped trace in a band adjacent the periphery of the circular chart).

Equally, more than one stylus may be provided with a respective hf component input, depending on the number of additional functions to be recorded.

Claims (16)

1. A tachograph comprising chart drive means for advan cing a recording chart with respect to time, and at least one stylus for recording a trace on said chart, characterised in that means are provided for imparting at least two distinguishable forms of movement to the same recording stylus, which forms of movement respectively represent different data inputs.

2. A tachograph according to claim 1, wherein one of said forms of movement imparted to the stylus is such as to cause a trace to be drawn having a stepped or oscillating waveform, characterised in that the other form of movement imparted to said stylus includes a relatively high frequency component.

3. A tachograph according to claim 2, characterised in that said high frequency component is applied such that said stylus oscillates or pulsates on one side only of the stepped or oscillating waveform.

4. A tachograph according to any one of claims 2-4, characterised in that means are provided to apply or not apply the high frequency component whereby the presence or absence of the same represents a function to be recorded.

5. A tachograph according to any one of claims 2-4, characterised in that the amplitude of said high frequency component is varied to represent variation in a function or functions to be recorded.

6. A tachograph according to any one of claims 2-5, characterised in that the frequency of said high frequency component is varied so as to represent the variation of a function or functions to be recorded.

7. A tachograph according to claim 5 or 6, characterised in that said amplitude or frequency variation, or both is achieved in steps.

8. A tachograph according to any one of claims 2-7, characterised in that said high frequency component is applied as either an oscillation, or pulsation.

9. A tachograph according to claim 2, wherein one of said forms of movement imparted to said stylus is that which provides a zig-zag odometer waveform, characterised in that said high frequency component is applied in said other form of movement imparted to said stylus to produce an oscillating or pulsating trace on one side of the zigzag waveform.

10. A tachograph according to claim 2, wherein one of said forms of movement imparted to said stylus is that which causes a stepped waveform to be recorded representing driver duty, characterised in that said high frequency component is applied in said other form of movement imparted to said stylus so as to produce an oscillating or pulsating trace on one side of the stepped waveform.

11. A tachograph according to any one of the preceding claims and having a dial which is normally visible to a user, there also being provided means for providing signals representing at least relatively high and low engine speed, characterised in that respective indicators are also provided on said dial which are operated by said signals.

12. A tachograph comprising means for advancing a chart with respect to time, at least one stylus coupled to means for imparting a first transverse motion which represents a first data input, characterised in that means are also provided for imparting at least a second transverse motion representing a second data input, said transverse motions of the stylus being transverse to the direction of motion of the chart with respect to time.

13. A tachograph according to claim 12, characterised in that said second transverse motion is such as to represent a discernible pulsation or oscillation at a relatively higher frequency than that of the first transverse motion.

14. A tachograph according to claim 13, characterised in that the amplitude, or frequency of the pulsation or oscillation, or both, is varied in accordance with the variation of a function or functions to be recorded on said chart.

15. A tachograph according to any one of claims 12-14, wherein said stylus is driven by a cam to impart said first transverse motion to the stylus, characterised in that said second transverse motion is imparted to said stylus by means of a solenoid connected, via a lost motion link, to said stylus.

16. A tachograph according to any one of claims 12-15, characterised in that said first and second transverse motions are imparted to said stylus by means of a stepper motor which is controlled by a microcomputer programmed to respond to various input functions.