The invention also relates to an arrangement for reducing the effect of acceleration in a vehicle, which arrangement comprises a base, platform, motor and mechanism for adjusting the tilt of the platform, acceleration sensor, and a control unit for the platform.

It is known that a person or persons inside a moving vehicle are susceptible to various tilting and acceleration forces exerted on the vehicle. Such forces exist in different situations, e. g. when the vehicle is moving fast or on an uneven surface.

Vehicles particularly susceptible to said forces typically include emergency vehicles such as ambulances, police cars and fire engines as well as work machines such as tractors, multi-process machines, wheeled and tracked excavators and the like.

Often the forces exerted on a person in a vehicle are considerable e. g. with respect to the person's state of health, as in the case of emergency medical transport, or as a result of the terrain or environment in which a vehicle such as a work machine is being operated. In many cases it would be desirable to compensate for the effect of these tilting and acceleration forces on a person, particularly a person positioned on a platform in a vehicle.

A stretcher patient transported in an ambulance is susceptible to forces caused by the movement and tilting of the vehicle. In a conventional ambulance, the stretcher platform is fixed during the transport so that acceleration forces are exerted directly on the patient. For a patient in a weak condition these acceleration forces may be detrimental or even fatal. However, in many cases it is imperative for the ambulance to move as fast as possible, further adding to the forces exerted on the patient.

While most of the known stretcher platforms are fixed constructions, solutions are known in which the stretcher platform can be tilted. These solutions, however, aim primarily to keep the stretcher platform horizontal, and in many solutions gyroscope systems or sensors are used to detect the vehicle position. Patent document WO 9410960 discloses a solution in which a sensor detects the position of the vehicle on the basis of which an electric mechanism is controlled to keep the

stretcher horizontal. In more developed versions acceleration sensors are used to detect accelerations exerted on the vehicle and change the position of the stretcher platform accordingly. One such solution is disclosed in patent document DE 19 809 903. In that solution the stretcher platform is attached in a fixed manner to the top of the ambulance through a joint and a control device. Acceleration sensors attached to the platform are used to control the motors which keep the stretcher platform level in spite of the tilting of the vehicle. Document EIX97403779311 discloses an ambulance stretcher control system designed to reduce fluctuation in the blood pressure of a patient during emergency braking. In this system an acceleration sensor is used to detect longitudinal acceleration or deceleration of the vehicle and to longitudinally tilt the stretcher according to the acceleration.

Document GB 1401473 discloses an arrangement in which the stretcher platform is pneumatically tilted controlled by a motion sensor. This tilting occurs along the longitudinal and transversal axes of the platform and the platform does not move from its position when it tilts. However, stretchers used in medical transport, as in ambulances, can usually be folded at least at one place so that the position of the patient can be adjusted during transport, e. g. by elevating one end of the stretcher.

Very often stretchers also have adjustments separately for the legs and for the upper body. This adds to the height of the stretcher during transport as the elevated portion of the stretcher, with a patient on it, requires considerably space in the vertical dimension. Using a simple stretcher platform that can be tilted laterally, such as the one described in the reference document GB 1401473, the elevated portion of the stretcher, when tilted, and the patient lying thereon take a large amount of lateral space in comparison with the basic horizontal position of the stretcher. This is problematic because usually there is in an ambulance, in addition to the stretcher and the stretcher platform, also cabinets for various instruments as well as paramedics'benches, located beside the stretcher, among other equipment.

Especially in critical situations, like when the patient is in shock, in which case the stretcher is positioned such that the foot-end thereof is raised high, a conventional tilting stretcher platform will produce an extensive lateral movement. In cramped space this leads to difficult working conditions in the ambulance and even to risk situations.

This same problem is also known to exist mutatis mutandis in work machines such as tractors, multi-process machines, wheeled and tracked excavators and the like, in which the driver sits in his seat susceptible to tilting forces. A work machine may

tilt very heavily e. g. because of the terrain in which it is operated. The driver will be constantly susceptible to strong tilting and acceleration forces which make work difficult and may result in health problems. Often the cabins of such work machines are very cramped and full of equipment needed in the operation of the machine, so there is not much room for the driver's seat. Because of the lack of space, it is difficult to provide a conventional tilting arrangement in the driver's seat which may also include a back support. The back support requires even more space when using a conventional tilting platform.

Further drawbacks of prior-art solutions include poor portability of equipment between vehicles. Moreover, not enough attention has been paid to compensating for the effect of lateral acceleration, but the main idea has been to just keep the stretcher or platform level. The gyroscope system used in some solutions for recognizing motion or position is expensive and large in size.

An object of this invention is to provide a novel platform applicable to existing vehicles and easily portable between vehicles without separately installed control equipment, which platform attempts to compensate for the lateral acceleration exerted on a person. In particular, the platform according to the invention saves space required for the tilting function by moving transversally when tilting.

The objects of the invention are achieved by an arrangement in which an apparatus is attached to a person-carrying platform in a vehicle so that the mechanics in the apparatus control the platform in such a manner that a force exerted on the person always tends to be directed perpendicular to the platform, and the platform, when it tilts, at the same time shifts transversally in the horizontal plane in the direction of the substantially lateral acceleration force exerted on the vehicle.

The method and arrangement according to the invention for reducing lateral acceleration are characterized in that which is specified in the independent claims.

Some preferred embodiments of the invention are specified in the dependent claims.

The basic idea of the invention is as follows: an acceleration sensor with associated control system and an electric mechanism for moving a stretcher platform are attached to a person-carrying platform in a vehicle, such as e. g. a stretcher platform for carrying a patient in an ambulance. On the basis of information obtained from the acceleration sensor the apparatus tilts the platform, when required, so that lateral acceleration is eliminated as far as the person is concerned, and the force exerted on the person is always directed perpendicular to the plane of the platform. At different

strengths of lateral acceleration and depending on the duration of the change of speed the platform is adjusted at different speeds and at different angles depending on the lateral acceleration caused by motion and on the duration of the change thereof. In addition, the platform moves sideways such that when it tilts, it also at the same time shifts transversally in the horizontal plane in the direction of the substantially lateral acceleration force exerted on the vehicle, whereby the center of gravity of the equipment remains in the middle region of the platform, thus saving space in the vehicle required for the tilt function. Furthermore, the platform tilts according to the tilting of the vehicle so that it is always in a level position, and because of its lateral movement the platform stays relatively in the same spot space- wise.

The mechanical implementation of the invention is simple. The platform according to the invention is hinged onto a base through one or more connecting element pairs located laterally parallel with each other. The connecting elements, advantageously metal rods, are hinged at the top and bottom ends both to the platform and to the base in such a manner that the connecting elements allow the platform to be tilted.

Tilting is controlled by a motor, advantageously an electric spindle drive attached to the platform and base in such a manner that the change in the length of a mechanism attached to the motor produces the desired tilting of the platform. The motor is driven on the basis of information obtained from an acceleration sensor.

Attaching the platform to the base through hinged connecting elements makes it possible to move the platform transversally in addition to tilting it.

An advantage of the invention is that the stretcher platform moves transversally so that when it tilts it at the same time moves in a direction opposite to the tilting, i. e. in the direction of the lateral acceleration force whereby the center of gravity of the equipment remains in the middle region of the platform, at the same time saving space required by the tilting of the platform within the vehicle.

Another advantage of the invention is that in a moving ambulance a force exerted on the patient always tends to be directed perpendicular to the plane of the stretcher.

A further advantage of the invention is that the apparatus includes both the control unit and the mechanics whereby it is easily transported from a vehicle to another by just connecting a power cable to the apparatus.

A further advantage of the invention is that when the vehicle is standing still the platform is always level regardless of the position of the vehicle.

A further advantage of the invention is that a mattress, seat or the like placed on the platform remains, relatively speaking, in its position when the vehicle tilts.

A further advantage of the invention is that it can also be used in various work machines to reduce tilting and acceleration forces exerted on the driver.

The invention will now be described in detail. Examples will be used to describe a preferred embodiment of the invention where the invention is applied to a stretcher platform in an ambulance. The description refers to the accompanying drawings in which Fig. la shows, as an example, an end view of a stretcher platform arrangement with the stretcher platform tilted, Fig. lb shows, as an example, a side view of a stretcher platform arrangement with the stretcher platform level, Fig. 2a shows, as an example, an arrangement according to the invention installed in an ambulance, with the stretcher platform level and an end portion of the stretcher raised, Fig. 2b shows, as an example, an arrangement according to the invention installed in an ambulance, with the stretcher platform tilted by an acceleration force and an end portion of the stretcher raised, Fig. 3a shows, as an example, an arrangement according to the invention installed in an ambulance, with the stretcher platform level and an end portion of the stretcher raised, and Fig. 3b shows, as an example, an arrangement according to the invention installed in an ambulance, with the stretcher platform tilted by the tilting of the vehicle and an end portion of the stretcher raised.

Fig. la shows, as an example, an end view of a preferred embodiment of the invention in which a platform serves as a stretcher platform in medical care transport. A stretcher 1 for carrying a patient and a mattress 2 are placed on a stretcher platform 3. The stretcher platform 3 is connected through pivots 5 to the base 6 of the arrangement by means of laterally parallel pairs of connecting elements 4, advantageously metal rods, which are attached to the stretcher platform 3 through pivots 12 at their upper ends. The base 6 of the arrangement is connected with the stretcher platform 3 through an electric motor 9 and an actuator mechanism

10 and pivots 8 and 11. On the basis of a signal from an acceleration sensor 13 an electronic control unit 14 drives the electric motor 9 to change the length of the actuator mechanism 10 in order to move the stretcher platform 3, thus tilting the latter. Fig. lb shows by way of example a side view of the same preferred embodiment of the invention with the stretcher platform level. In this embodiment of the invention there are two support and motion systems comprised of the connecting elements 4: one at the head-end of the base 6 and one at the foot-end thereof. The figure shows a stretcher portion 7 which can be raised. The raised position of the end portion 7 of the stretcher is depicted in broken line.

Fig. 2a shows by way of example a preferred arrangement of the invention in which the apparatus is installed on the floor of an ambulance 20 and the arrangement is viewed from the direction of the rear of the vehicle and an end portion 7 of the stretcher is raised. The stretcher 1 is placed on a stretcher platform 3 according to the arrangement and a portion 7 of the stretcher is raised. The stretcher platform 3 is attached to the base 6 of the arrangement through metal rods 4. An electric motor 9 and a mechanism 10 attached thereto connect the stretcher platform 9 with the base 6 of the apparatus. Fig. 2b shows by way of example the same arrangement in a situation in which an acceleration force 30 is exerted on the vehicle, to the right, and the stretcher platform 3 is accordingly tilted to the left with stretcher portion 7 raised. In this situation the motor 9 has controlled the actuator mechanism 10 so that the arm of the mechanism has been extended. The mechanism will then push the right side of the stretcher platform up, thereby tilting the platform to the left and at the same time shift it horizontally to the right, to the direction of the acceleration force 30. Because of the transversal shift of the platform 3, the raised end portion 7 of the stretcher requires less space outside the arrangement proper than without the transversal shift.

Fig. 3b shows the same arrangement according to the invention in a situation in which the vehicle 20 is tilted. As a consequence, the platform 3 compensates for the tilting of the vehicle 20 by positioning itself in level position. Even if the platform 3 moves transversally with respect to the vehicle 20, its center point will not move transversally relative to space, but the movement only compensates for the shifting or tilting of the vehicle. Comparing to Fig. 3a, where the vehicle 20 and platform 3 are horizontal, it can be seen that in Fig. 3b the platform remains relatively speaking in the same position even though the vehicle 20 around it is tilted.

Some preferred embodiments of the invention were described above. The invention is not limited to the solutions just described. For example, in addition to an

ambulance and the work machines mentioned above the invention is applicable in other types of vehicle, too, which are susceptible to tilting and acceleration forces. The quantity of said connecting elements may be different and they may have different constructions. Moreover, the motor adjusting the platform and the mechanism connected therewith may be different. The inventional idea can be applied in numerous ways within the scope of the invention defined by the claims attached hereto.