PRAM, FRAME AND METHOD FOR AUTOMATIC ROCKING

Abstract

A pram with a frame, which has a pusher and wheels for driving the pram, a drive, which is drive-connected to at least one of the wheels, and a braking device for at least one wheel, which is transferable into a driving state with free wheel rotation and into a braked state with at least one braked wheel, wherein the drive can be actuated for an automatic rocking function of the pram, wherein the wheel braked by the braking device is rotatable to a limited extent in both wheel circumferential directions in the braked state for automatic rocking of the pram.

Claims

1. A pram with a frame which has a pusher and wheels for driving the pram, a drive which is drive-connected to at least one of the wheels, and a braking device for at least one wheel, which is transferable into a driving state with free wheel rotation and into a braked state with at least one braked wheel, wherein the drive is actuable for an automatic rocking function of the pram, and wherein the wheel braked by the braking device can be rotated to a limited extent in both wheel circumferential directions in the braked state for automatic rocking of the pram.

2. The pram according to claim 1, wherein the braking device comprises a parking brake.

3. The pram according to claim 1, wherein the braking device has several braking positions at different wheel angle positions, each of which enables the rotation, which is limited in both wheel circumferential directions, of the braked wheel.

4. The pram according to claim 1, wherein the braking device has an engagement means and/or an engagement recess, in particular an engagement opening, which interact/interacts with a corresponding engagement opening or a corresponding engagement means of the respective wheel for braking.

5. The pram according to claim 4, wherein an inner circumference of the engagement recess, in particular engagement opening, is larger than an outer circumference of the engagement means in order to form a play in the wheel circumferential direction.

6. The pram according to claim 4, wherein the engagement means comprises a pin and the engagement recess, in particular engagement opening, comprises a corresponding pin receptacle, wherein the pin receptacle has a length which is greater than the pin diameter.

7. The pram according to claim 6, wherein the pin receptacle extends in a longitudinal direction along a partial circumference of a wheel.

8. The pram according to claim 1, wherein the drive has at least one motor, in particular an electric motor, at least one energy source, in particular a battery or accumulator, at least one sensor and/or a control unit.

9. The pram according to claim 8, wherein the motor is arranged on a rear axle of the frame or is designed as a hub motor.

10. The pram according to claim 8, wherein the drive or a part of the drive, in particular comprising the motor and/or the accumulator, is designed as a removable module.

11. The pram according to claim 8, wherein the control unit is designed for analysing detected data and controlling the motor.

12. The pram according to claim 8, wherein the control unit is configured in such a way that a braked state of the pram is detected, upon actuation of the rocking function rocking distance of the pram is automatically moved back and forth by the drive, and a beginning and an end of the rocking distance are each limited by a blockade of at least one wheel.

13. The pram according to claim 12, wherein the control unit is configured in such a way that a power of the drive is increased after the beginning of the rocking distance and reduced before the end of the rocking distance.

14. The pram according to claim 12, wherein the control unit is configured in such a way that a power of the drive is reduced after 20%-80%, in particular 30%-60%, for example 50%, of the rocking distance.

15. The pram according to claim 12, wherein the control unit is configured in such a way that a power of the drive is changed reciprocally each time the rocking distance is travelled.

16. A frame for a pram, which has a pusher and wheels for driving the frame, a drive which is drive-connected to at least one of the wheels, and a braking device for at least one wheel, which is transferable into a driving state with free wheel rotation and into a braked state with at least one braked wheel, wherein the drive is actuable for an automatic rocking function of the frame, wherein the wheel braked by the braking device is rotatable to a limited extent in both wheel circumferential directions in the braked state for automatic rocking of the frame.

17. A method for automatically rocking a pram with a rocking function, in particular a pram according to claim 1, in which a braked state of the pram is detected, a rocking distance of the pram is automatically moved back and forth by a drive upon actuation of the rocking function, and a beginning and an end of the rocking section distance are each limited by a blockage of at least one wheel.

18. The method according to claim 17, wherein a power of the drive is increased after the start beginning of the rocking distance section and is reduced before the end of the rocking distance.

19. The method according to claim 18, wherein the power of the drive is reduced after 20%-80%, in particular 30%-60%, for example approximately 50% of the rocking distance.

20. The method according to claim 17, wherein a power of the drive is reduced to zero after a holding time after the end of the rocking distance has been reached.

21. The method according to claim 17, wherein a drive is switched off when a maximum rocking distance is exceeded by the pram.

22. The method according to claim 17, wherein a power of the drive is changed reciprocally each time the rocking distance is travelled.

23. The method according to claim 17, wherein a length of the rocking distance is adjusted or set to different sizes.

24. The method according to claim 17, wherein a length of the rocking distance is automatically adjusted to shorter or longer rocking distances during a rocking period.

Description

[0061] The invention is explained in more detail by means of an embodiment example with reference to the attached schematic figures with further details.

[0062] In these show

[0063] FIG. 1 an example of the structure of a pram with drive for pushing support according to the prior art;

[0064] FIG. 2 a top view of a braked wheel with a braking device of a pram according to an embodiment example according to the invention in a first position;

[0065] FIG. 3 the braking device according to FIG. 2 in a second position and

[0066] FIG. 4 the power curve of the drive in relation to the wheel position of a pram according to an embodiment example according to the invention.

[0067] FIG. 1 shows a pram according to the prior art with a drive 13, which is arranged in the lower area of the frame 10 of the pram. The invention is applicable to such a pram and enables the implementation of an automatic rocking function using the drive 13, which is additionally provided in the known pram to support the pushing function. The basic construction of the pram according to the embodiment example according to the invention is described with reference to the known pram, which otherwise does not show the rocking function in conjunction with the extended braking function.

[0068] The invention or the embodiment examples according to the invention use the drive 13 provided to support the pushing function additionally to realise the automatic rocking functions. Instead of this dual function of the drive 13, a separate drive can be provided for the rocking function. In contrast, the dual function has the advantage that the pram is built compactly and lightweight, as the number of drives 13 is reduced. The drive 13 can be actuated accordingly for the automatic rocking function of the pram. The actuation of the drive 13 can be done by a corresponding control unit. In any case, the drive 13 is designed such that upon actuation of the drive 13, the rocking function takes place automatically, i.e. without manual intervention. To this end, the drive 13 enables an automatic reversal of the direction of travel, as when rocking a pram by manual application of force.

[0069] In the pram according to FIG. 1, the drive 13 comprises a hub motor which is drive-connected to at least one of the rear wheels 12. Other motors and motor arrangements are possible. The frame 10 comprises a pusher 11 with a handle as well as wheels 12, which are rotatably connected to the frame 10. Here too, different designs of the frame 10 are possible, for example designs with three or four wheels. The invention is not limited to a specific configuration of the frame 10.

[0070] The drive 13 comprises a motor 17, for example an electric motor, an energy source such as a battery or an accumulator, one or more detection units (sensors) and/or a control. The energy source, the sensors or the control are not shown in FIG. 1. The sensors can be designed to detect a rotation of the at least one braked wheel 12, in particular to measure an angle of rotation of the braked wheel 12. Preferably, the sensors can additionally detect a rotation of the motor 17. With the aid of a further sensor it can monitored whether the braking device 14, in particular the parking brake, is activated. This serves the purpose of safety, as the rocking function is prevented in the case of not-activated parking brake. Alternatively or in addition to this safety, the speed of the pram or other corresponding parameters can be measured in order to prevent the rocking function from being triggered upon driving of the pram.

[0071] The mounting unit 18 is used to mount a baby or small child and is connected to the frame 10, for example by an adapter or permanently connected. The mounting unit 18 is preferably designed as a reclining unit, in particular as a carrycot and/or infant carrier. Seat attachments, which can be moved into a reclining position if necessary, are also possible.

[0072] The control unit, not shown in FIG. 1, is designed for the analysation of the data detected by the sensors and, based on this, for the control of the drive unit 13, in particular the motor 17. Also not shown in FIG. 1 is the braking device 14 shown in FIGS. 2, 3, which can be transferred into a driving state and into a braked state. In the driving state, the braking device 14 is released and allows a free rotation of the wheels so that the pram can be pushed unhindered. In the braked state of the braking device 14, at least one wheel 12 is braked. Preferably, the braking device 14 and the drive 13 act on one and the same wheel 12. The braking device 14 of the pram has so much play that a linear movement or a back and forth movement of the pram is possible, which essentially corresponds to a manual rocking movement. For this purpose, the wheel 12 braked by the braking device 14 can be rotated to a limited extent in both wheel circumferential directions in the braked state.

[0073] FIGS. 2, 3 show an embodiment example of the pram according to the invention or the frame for a pram according to the invention, in which the braking device 14 is constructed in such a way that rotation of the wheel, in particular of the driven wheel 12, is enabled to a limited extent in the braked state (partial rotation). For this purpose, the braking device 14 has an engagement means 15, which in the embodiment example according to FIG. 2 is designed as a stud or pin 15. The pin 15 extends parallel to the hub axis of the wheel 12 and projects outwards in relation to the frame 10 in order to be able to interact with a complementary engagement opening 16 of the wheel 12. The engagement opening 16 is designed as a pin receptacle for the pin 15.

[0074] The braking device 14 is therefore a parking brake because the pin 15 in the pin receptacle or engagement opening 16 blocks a rotation of the wheel 12.

[0075] A comparison of FIGS. 2 and 3 shows that the pin 15 assumes different positions relative to the wheel 12 or to the engagement opening 16. The different positions of the pin 15 illustrate the braking play of the braking device 4, which is used in the embodiment example according to FIGS. 2 and 3 to implement the automatic, motorised rocking function of the pram.

[0076] In FIG. 2, the pin 5 is in the lower position and butts on a first inner side of the engagement opening 16. By this a rotation of the wheel 12 in a clockwise direction (in the view shown in FIG. 2) is prevented. FIG. 3 shows the upper position of the pin 15 in the engagement opening 16, in which the pin 15 butts on a second inner side of the engagement opening 16. By this a movement of the wheel 16 in an anti-clockwise direction is prevented. The first and second inner sides of the engagement opening 16 are arranged opposite each other in the circumferential direction of the wheel 12, so that a sufficiently large free space of the engagement opening 16 is formed between the two inner sides, in which the pin 15 can perform the desired partial rotation relative to the wheel 12 or vice versa.

[0077] In other words, the length of the engagement opening 16 extending in the circumferential direction is greater than the diameter of the pin 15. The first and second inner sides of the engagement opening 16, which determine the partial rotation of the wheel 12 in the braked state, are spaced apart that far from one another that the desired rocking distance of the pram for the rocking movement can be travelled.

[0078] The width of the engagement opening 16 extends in the radial direction of the wheel 12. The width of the engagement opening 15 corresponds to at least the diameter of the pin 15 or is greater than this.

[0079] According to embodiment, the pin 15 can be brought into at least two positions in a direction perpendicular to the drawing plane of FIGS. 2 and 3, namely into a first position in which it engages in one of the engagement openings 16 and into a second, retracted position in which it is out of engagement with the engagement openings 16.

[0080] The shape of the engagement opening 16 is not limited to the contour shown in FIGS. 2, 3. Other shapes are possible.

[0081] In FIGS. 2, 3 it is readily recognizable that several engagement openings 16 are arranged around the circumference of the wheel, which are identically designed so that there are various engagement possibilities for the pin 15. The rocking function is possible in any position due to the matching brake play or the identical length of the engagement openings 16.

[0082] The mode of operation of the embodiment example according to FIG. 2 and FIG. 3 is explained using the graph in FIG. 4. FIG. 4 illustrates the interaction of the drive 13 and the braking device 14.

[0083] The upper partial figure in FIG. 4 exemplarily shows the power curve of the drive 13 or of the motor 17 over time in the braked state and during automatic rocking. The lower partial figure in FIG. 4 shows the corresponding wheel positions of the wheel 12 in the braked state during the rocking movement. The centres of the two wheel positions correspond to the maximum rocking distance, i.e. the linear movement of the pram when moving back and forth. The two maximum wheel positions are defined by the braking device 4, which limit the start and the end of the partial rotation of the wheel 12 shown in the lower partial figure of FIG. 4. In the left-hand position of the wheel 12 in FIG. 4, the pin 15 according to FIG. 3 butts on one inner surface of the engagement opening 16, so that a further movement of the wheel 12 is prevented (back end stop). The same applies to the other wheel position (front end-stop) in FIG. 4, which is defined by the stop of the pin 15 on the other inner surface of the engagement opening 16.

[0084] The upper partial figure in FIG. 4 shows the power curve of the drive 13 or of the motor 17, which determines the speed profile of the wheel movement. After the start of the rocking distance, the power initially increases with the gradient alpha to a maximum value Pmax, e.g. to 70% of the total motor power. The maximum value Pmax is reached after approximately half of the rocking distance, as can be seen from the comparison with the lower partial figure according to FIG. 4. Other times are possible. After reaching the maximum power Pmax, this drops to the minimum value Pmin, e.g. to 7% of the total motor power, which is kept constant until the end of the rocking distance, so that the rocking movement is gently slowed down by the pin 15 butting on the inside of the engagement opening 16. The power is maintained on the minimum value Pmin during a holding time beyond the butting-on of the pin 15 on the inner surface of the engagement opening 16 in order to achieve that the motor 17 stops before the reversal of movement is initiated.

[0085] The time Tc between the start of the power increase and the end of the holding time defines a rocking phase, in the example according to FIG. 4 a forward movement of the pram. The incline alpha and the time Tc of the rocking phase together influence the rocking movement. The greater the incline and the shorter the time Tc, the stronger the rocking movement. For the entire rocking process, the direction of force is reversed or the direction of rotation of the motor is changed after the end of the holding time, so that a reciprocal movement takes place, which results in a backward movement of the pram. In this, the power of the motor runs through the same course as shown in FIG. 4, but in the opposite direction. The rocking movement is therefore determined overall by the interaction of the braking device 4 in the braked state on the one hand and the drive 13 or the power curve of the motor 17 over time on the other. By the decoupling of the deceleration by the braking device 4 on the one hand and the movement of the wheel 16 by the drive 13 on the other, the process control is improved in addition to the safety during the automatic rocking, because the motor 17 is activated beyond the stop of the braking device 4 in order to achieve a safe reversal of movement.

[0086] The method according to the example embodiment shown can comprise the following steps: [0087] 1. switching on the rocking function (by switch or via app) [0088] 2. detecting whether the parking brake is active (if not: cancellation) [0089] 3. applying a force to the at least one wheel via the motor, (possibly linear) increase in motor power [0090] 4. detect how far the wheel has turned (with a sufficiently high frequency, e.g. 20 Hz-100 Hz) [0091] 5. when the desired proportion (20%-80%, preferably 30%-60%, e.g. 50%) of the predefined rotation is reached, the motor power is reduced (to a predefined value that can be less than 50%, preferably less than 30% of the maximum motor power, e.g. 7% or 15%) [0092] 6. maintaining the reduced motor power until the motor stops rotating (because according to the embodiment the pin butts on the end of the hole) [0093] 7. applying a force to the at least one wheel (in comparison to 3. in the opposite direction) by the motor, (possibly linear) increase in motor power [0094] 8. steps 4-6, then continue with 3 [0095] 9. cancellation by an event from the following list: (it is not necessary for all the cancellation criteria mentioned to be implemented) [0096] a. switching off of the rocking function [0097] b. deactivation of the parking brake [0098] c. rotation exceeds predetermined value, in particular more than 100% of the predefined rotation, e.g. 120% or 150% [0099] d. energy of the energy source drops to or below predefined value.

[0100] According to embodiment, the motor power in 3. or 7. can be limited to a predefined value (in particular >50% of the maximum motor power and/or <90% of the maximum motor power), for example 60%-80%, e.g. 70% or 75%.

[0101] According to embodiment, in 6. the reduced motor power can still be maintained for a predefined time (holding time).

[0102] At this point, it should be pointed out that all of the parts described above are claimed to be essential to the invention when viewed individually and in any combination, in particular the details shown in the drawings. Modifications thereof are familiar to the skilled person.

[0103] Furthermore, it is pointed out that a scope of protection as broads as possible is sought. In this respect, the disclosure contained in the claims can also be specified by features that are described with further features (even without these further features necessarily being included). It is explicitly pointed out that round brackets and the term in particular are intended to emphasise the optionality of features in the respective context, which does not mean, conversely, that a feature is to be regarded as mandatory in the corresponding context without such identification.

Reference Signs

[0104] 10 frame [0105] 11 pusher [0106] 12 wheels [0107] 13 drive [0108] 14 braking device [0109] 15 engagement means [0110] 16 engagement opening [0111] 17 motor [0112] 18 mounting unit