FIELD OF INVENTION AND PRIOR ART

This invention relates to a safety arrangement for a vehicle comprising a manually operated control member. It is known to co-ordinate such a control member with an electrical sensing device for sensing whether the driver of the vehicle has an adequate grip of the contr member. Furthermore, it is known to make this sensing device control a device for delivering warning signals and/or carrying out operations to stop movement of the vehicle when the sensing device has established that th driver no longer has an adequate grip of the control member. Finally, it is known by the US patent 3 186 508 to provice means inactivating the warning and/or stoppi device as soon as the vehicle is driven at a speed belo a certain threshold value. Such a speed control of the safety arrangement causes, however, a rather complicate design. Furthermore, the negative result is obtained th the safety arrangement unnecessarily will be brought in a supervising state since the speed threshold, in order to avoid unnecessary risk, must be set so low that it probably will be exceeded rather often at such accelera tions with low gear into a relatively high speed which occur during traffic in densely built areas,queues or th like. Furthermore, a safety arrangement controlled on t basis of speed must have means to ensure that the safet function, after having been initiated, does not cease in connection with a speed reduction following thereon.

BRIEF DISCLOSURE OF THE INVENTION The present invention aims at developing the safety arrangement defined in the preamble of appendent claim 1 so as to make the same more simple and reliable than the safety arrangement previously known and discussed hereinabove while maintaining an efficient operation.

This object is obtained, in accordance with the inventi by the features presented in the characterizing portion of claim 1. Thus, by allowing the safety action to be dependent from the set transmission ratio, an embodimen is obtained which is easy to realize; the gear selector can be designed to actuate a simple switch for switchin on or off of the safety action. Furthermore, the advant geous effect is obtained that if the driver would be hi by disease or tiredness or otherwise be put into a cond tion insufficient for driving while the gear selector i in such a position that the safety function is activate the driver will not be able to move the gear selector o of the active position in question so that accordingly the safety function remains active without need of par- ticular equipment for ensuring the same.

In accordance with a preferred embodiment of the inven¬ tion, the control member is designed for two hand grip, the first mentioned sensing device being divided into two components, each being so arranged on the control member that they on normal gripof thecontrol member are gripped by one of the hands of the driver and which are arranged in series with each other so that inadequate grip of one of the hands of the driver will give rise t inactivation, possibly after a time delay, of the warnin and/or stopping device. In this way an embodiment is ob tained which will make the driver used to always grip t control member in the way which is the most safe for th traffic.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, a more specifi disclosure of a preferred embodiment of the invention will follow hereinafter.

In the drawings:

Fig 1 is a diagrammatical view of a steering-wheel provi with a sensing device;

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fig 2 is a detailed view illustrating the function of the sensing device; and fig 3 is a diagrammatical view illustrating the design of the safety arrangement.

DETAILED DISCLOSURE OF A PREFERRED EMBODIMENT

The safety arrangement according to the invention is intended for vehicles comprising a manually operated control member. In general, the control member is in t form of a steering-wheel 1 (Fig 1 ). To the steering-wh there is associated an electrical sensing device 2 for sensing whether the driver of the vehicle has an adequ grip of the control member. The sensing device may for instance be formed by a contact device, the two contac 3, 4 of which (Fig 2) have the shape of electrically c ductive bands or the like extending along the rim of t steering-wheel, preferably on the inside thereof. Thes bands may be embedded into a flexible rubber material the like on the rim of the steering-wheel. The contact bands 3, 4 are in an unactuated state located at a certa distance from each other. The contact bands 3, 4 are so arranged relative to each other that they due to the pressure from the thumb or the hand for the rest which is exercised by the driver on normal drive grip of the steering-wheel are pressed against each other (se the arrow in fig 2) so that they enter into electrical conta with each other and thereby close an electrical circuit which is connected to a device 5 (Fig 3) for delivering warning signals and/or carrying out operations to stop movement of the vehicle. Also other designs of the sen- sing device 2 are conceivable; the essential thing for the concept of the invention is that the sensing device in question should be capable of sensing and indicating such a change of the grip of the driver of the vehicle which occurs when the driver falls asleep or otherwise turns into a state in which driving is impossible. Inve tigations illustrate that the grip of the steering-whee is loosened when the driver falls asleep or dozes off.

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The safety arrangement according to the invention is intended to be applied to vehicles having a driving pow transmission with variable transmission ratio. A second sensing device 6 is adapted to derive information as t actual transmission ratio and to allow function of the warning and stopping device 5 when the transmission rat has a value corresponding to speeds in the upper speed range of the vehicle but inhibit said function when th transmission ratio corresponds to speeds in the lower speed range of the vehicle.

For a vehicle having a manually controlled gear unit, t second sensing device 6 is adapted to allow function of the warning and stopping device 5 only when a gear sele (gear shift leaver 7) of the gear unit is in any of the higher gear positions. In fig 3, it is diagrammatically illustrated that the gear unit has four forward positio and a back position R. With such a gear unit, it is pre ferred that the sensing device 6 puts the safety arrang ment into a state of function only when the gear lever 7 is in the fourthand highest gear position.

The sensing device 6 is formed by a switch actuated by the gear lever 7, said switch connecting one contact member 3 of the contact device 2 to a current source wh the gear lever is in the fourth gear position (see fig 3) The second contact member 4 is, in a manner which will be discussed more closely hereinbelow, coupled to a rel or other connecting member 8 which is designed to be de-energized or otherwise switch over when no current flows through the conductor 9 so that a warning lamp 10 visible by the driver and/or a buzzer apparatus 11, which can be heard by the driver, is supplied with curr Such a situation cannot occur when the gear lever 7 is in other positions than the fourth gear position since a spring 12 then causes the switch 6 to close an elect- rical circuit via the conductor portion 13 which passes by the contact device 2 and directly adjoins to the con ductor 9. On the contrary, when the gear lever 7 is in the fourth position the switch 6 closes the current pat

to the contact device 2 and when the driver with his hand presses the contact members 3 and 4 towards or against each other in ordinary way, contact therebetwee will be established and the current circuit will be clo The sensing device 2 is divided into two components 14, 15, each of which are so arranged on the steering-wheel 1 that they on normal grip thereof are gripped by one of the hands of the driver. The components 14, 15 are located in such areas of the steering-wheel where hand grip on driving straight forwardly is compatible with traffic safe driving. Positions of the hands generally in "ten o'clock" and "two o'clock" are as a rule consi¬ dered to be the most appropriate, for what reason the components 14, 15 of the sensing device should be arran in correspondence thereto with some overlapping upwardl and downwardly on the steering-wheel. It is desirable t the components 14 and 15 are not located in the lowermo part of the steering-wheel and neither in its uppermost part. One 14 of the components of the sensing device comprise the contact members 3, 4 already described, while the other component comprises corresponding contact members 3' and 4'. It is essential according to the invention that the components 14 and 15 are connected in series with each other such that inadequate grip of one of the hands of the driver is sufficient to give rise to activa tion of the warning and stopping device 5. In order to maintain the warning and stopping device 5 inactivated, the driver must accordingly establish the required elect rical contact not only between the contact members 3, 4 of the component 14 but also between the contact members 3', 4' of the component 15.

When the current supply to the relay 8 is interrupted an the warning light 10 and buzzer 11 are put into operatio the relay 8 simultaneously, via conductor 16, closes the urrent circuit to a relay 17 which is deenergized and closes the current circuit to for instance the warning

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flashers 18 of the vehicle and interrupts thecurrent circuit to the ignition system 19 (on vehicles powered by petrol) of the vehicle so that accordingly the motor of the vehicle no longer drives the vehicle but a motor retarded function occurs with a controlled reduction of the speed of the vehicle. If a diesel vehicle is in view, the relay 17 instead interrupts thecurrent supply to the injection pump or the like of the diesel motor. It is preferred that the relay 17 operates with a tim delay of for instance 5 seconds so that the driver may shift hand grip on the steering-wheel and without obsta shift gear without initiating stoppage of the vehicle. It is also possible to design the relay 8 with some tim delay so that the warning light 10 and buzzer '11 are no activated until after a delay which is somewhat longer than allowable shifting of the grip of the steering-whe

The relays 8 and 17 can of course be electronic compone of semi-conductor type.

The invention is also applicable to vehicles having aut matic transmissions, in which case the sensing device 6 may have another design than the one diagrammatically illustrated herein. With automatical gear units havin distinct steps, the sensing device 6 may be adapted to close the current circuit when the transmission is set into the highest step.

With manual gear units having four or fewer gears, it i in general sufficient that the sensing device 6 closes the current circuit in the highest gear position. With vehicles having five or more gears, closing may occur o two or more of the highest gears.

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