Article
citation information:
Kowalski, S. Sample structural
solution for a city tricycle with an additional solar drive. Scientific Journal of Silesian University of
Technology. Series Transport. 2020, 109,
85-92. ISSN: 0209-3324. DOI: https://doi.org/10.20858/sjsutst.2020.109.8.
Sławomir KOWALSKI[1]
SAMPLE
STRUCTURAL SOLUTION FOR A CITY TRICYCLE WITH AN ADDITIONAL SOLAR DRIVE
Summary. The everyday use of the
bicycle is becoming increasingly common. People noticed the need to take care
of both their health and the environment. The geographical location of
Poland encourages cycling, which is the reason new kilometres of cycling routes
are being built every year. This is associated with the rising interest in
buying a bicycle. A conceptual tricycle with an additional electric drive
powered by solar panels is presented in this article. The photovoltaic panel is
installed on the basket roof. The electric motor may be used during an uphill
ride and when the driver has run out of energy for pedalling. In the crank
mechanism, there is a sensor which starts the motor when a small foot pressing
force on the pedal is detected. The tricycle has an all-purpose structure,
owing to which the seat mounted in the basket can be easily replaced with a
double seat, a shopping bin or a child's safety seat. The tricycle may be
used by both private persons and companies involved in tourist transport. The
cost of the structural details of the tricycle suggested in this article does
vary considerably from standard electric bikes, however, that solution has
several important advantages, which may be decisive in the purchase of this
solution.
Keywords: city bike, electric bike, solar drive, cycling
infrastructure, active tourism
1. INTRODUCTION
A
growing interest in not only bicycle touring but in everyday cycling as well is
observed every year. Usually, a bike becomes an ever-present element of
people's lives and is used, for example, as a means of transport for going to
work or shops; a fact which follows from the wish to enjoy a healthy lifestyle
and for the care of the natural environment. A bike may also be a good
alternative to cars, frequently moving around at a low speed due to increasing
congestion [7,10].
Many
bike models can be found in the market, which makes it easier to choose a bike
according to one's needs and preferences. By browsing through bike
manufacturers' catalogues, one can find city, trekking and mountain bikes.
Traditional human-powered bikes and those equipped with an additional drive are
available too. The electric drive is the most used.
Electric
bikes are more economical compared to combustion engine vehicles. They have
cheaper maintenance cost contrary to using a car. Whereas 100 km of driving
costs as much as around PLN 50, covering the same distance by electric bike may
cost approximately PLN 1. Given the constant growth of fuel costs, travel
by electric bike seems an appropriate alternative for motor vehicles. An electric
bike does not need registration or motor insurance, which reduces the vehicle
maintenance cost [13].
Besides,
current structural solutions make it possible to build small and lightweight
motors with a high power/weight ratio. The development of energy storage
technology permits the construction of lightweight batteries with big storage
capacity, which increases the vehicle range [1].
Keeping
an eye on the continuous growth of interest in bicycle touring, local
governments allocate funds for the construction of new or the extension of
existing cycling paths. This is confirmed by statistical data on cycling path
length. Data in [9] show that the length of cycling paths increases every year
(Fig. 1). The length of cycling paths in Poland has increased by 8,121.9 km
over the last seven years.
Fig. 1. Length of cycling paths in Poland (on basic [5])
The
length of cycling paths by region is shown in Fig. 2. The statistical data from
the Central Statistical Office of Poland are from the year 2018. The first one
in the league is the Mazowieckie region, where the
length of cycling routes is 1,995.6 km, and the Wielkopolskie
region comes second with 1,824.4 km. According to statistical data of 2019 from
the Polish Tourist Organisation, cycling comes third among the Poles' holiday
activities [5].
Approximately,
every tenth Pole (9%) declares that he or she has taken part in a trip
organised by himself or herself, during which trip a bike was used as a means
of transport [5].
Fig. 2. Length of cycling paths in regions in 2018 (on basic [5])
In
addition to investing in new cycling paths, local governments in bigger cities
offer city bike rental. Presently, there are several city bike rental services
in operation in Poland, including Cracow, Warsaw, Rzeszów,
Wrocław, Opole, Poznań,
Sopot and Białystok [4]. Bikes at such rental
services are usually manufactured upon order from rental companies. The
tricycle proposed in this article seems to be an appropriate solution in terms
of its functionality described in section 2.
The
concept of the creation is the EuroVelo and other
similar cycling routes, for example, VeloDunajec,
AquaVelo, GreenVelo, VeloNatura, Szlak Stu Jezior or VeloBaltica, is an
incentive to participate in bicycle touring. All of these routes run across
the regions of Poland and Europe, which are attractive to tourists. The
length of each of those routes is significantly longer than one hundred
kilometres. An appropriate bike is needed to cover the whole length. An
electric tricycle powered by solar energy will permit riding long
distances. When the cyclist feels tired, the drive can actuate automatically,
without the need to stop and charge batteries, because the solar panels
absorb sunlight all the time, thus, keeping the batteries fully ready for use.
Bicycle
touring is a form of tourism in which a bike is the main means of transport [8].
Such tourism may be heritage or competitive in nature and is counted as
qualified tourism. It is practised both individually and in groups, for
example, in bicycle touring clubs. Bicycle touring is of special importance in
spatial design in terms of the development of tourist facilities. The
development of tourism is taken into consideration at both the local and the
regional level [6]. Many forms of bicycle touring may be distinguished
depending on the following criteria: the motive (relaxation, exploring, and
qualified bicycle touring), landscape type (seaside, lake, lowland, mountain
and city bicycle touring), distance (short- and long-distance bicycle touring),
age (touring for children, young persons, adults, families with children and
for senior citizens), and the bike type in use (cycling touring, MTB, trekking
and city bicycle touring) [11].
2. THE CONCEPT
OF A TRICYCLE WITH AN ADDITIONAL DRIVE
The aim of this article is
to propose a city tricycle, which will permit the transport of people over
considerable distances and make everyday life easier. A tricycle with a basket
mounted in its front part will be the best solution. The bicycle concept developed
by Ewelina Tokarz is
presented in Fig. 3 and presented in the thesis [12]. The proposed tricycle
shown in Fig. 3 may be an alternative for motor vehicles. Due to the
ever-changing climate, there is a steady decline in rainy and cold days in
Poland, with less snowfall in winter as well. This situation presents the
incentive to take advantage of an environmentally friendly means of transport.
The proposed tricycle will be a good alternative for private persons, who
may use it to commute to work or shops, and for companies dealing in passenger
transport. The tricycle may become a tourist attraction and be used to carry
people who would like to visit the surroundings without a pedalling effort.
a 
b 
Fig. 3.
Design of the tricycle [12]: a) the overview, b) the solar panel
The underlying idea of the
trolley structure is to easily remove the seat installed in the basket and
install a double seat, cargo bin or child's safety seat instead.
The tricycle has an
additional electric drive powered by the solar system. The photovoltaic panel
is installed on the basket roof. The electric motor may be used both during an
uphill ride and when the driver has run out of energy for pedalling. In the
crank mechanism, there is a sensor, which starts the motor when a small
foot pressing force on the pedal is detected. The handlebars have a controller,
which permits the adjustment of the capacity at which the motor works. Pressing
the brake causes automatic drive disconnection and motor shut down. This is a
form of protection, owing to which the cyclist will be sure that the tricycle
will not move without his or her knowledge.
Although the time of battery
charging from the mains power supply is approximately 3-5 hours, the time of
battery charging with the current from the photovoltaic panel is 5-8 hours and
depends on weather conditions. The advantage of the latter solution, however,
is that the battery is charged continuously without the need to look for an
electric socket. This function is very useful during long trips to undeveloped
areas and allows a longer distance to be covered at the same time. The storage
battery may also be charged by generally accessible power banks, however,
charging time is long and depends on the efficiency of the device. Electric
energy recovery by batteries during braking, for example, during a downhill
ride, is another form of battery charging. In this case, energy recovery is
insignificant and will not permit long distance travel.
Furthermore, an electric
drive system installed on the tricycle enables the charging of electronic
devices such as a mobile telephone, tablet, etc. through a USB connector.
The diagram of the solar
system installed in the planned tricycle is shown in Fig. 4.
Fig. 4. Diagram of the solar system in the design tricycle [12]
The main tricycle design criteria are as
follows:
·
The tricycle frame will be
made of lightweight materials and painted silver. The frame will be protected
against corrosion by painting with anti-corrosion paints. In this type of
tricycle, the use of carbon fibres for frame manufacture would be the best solution,
but the costs of tricycle production would increase considerably. The objective
is for the tricycle to be affordable to all.
·
The transmission system will
have 7 gears and be fitted in the wheel hub. The main advantage of such a
solution is a lower failure frequency of the system. The gears are fully
protected from weather conditions, hence, require less service. Shimano shifters
will be used.
·
V-brakes will be used. In
view of their construction, brakes of this type have greater braking power
compared to other solutions. They are also more durable, which will permit a
greater number of braking cycles.
·
Tricycle lighting will be
based on LED's owing to which the tricycle will be visible from a considerable
distance. The route in front of the tricycle will be well-lit and the driver
will enjoy better visibility. Consumption of electric energy will decrease as
well. To generate electricity, a magnetic dynamo will be used, which generates
power with the use of magnets installed on the spokes. This type of solution
does not produce sound and reduces rolling resistance. Standard reflectors will
also be used on the pedals, wheels, and the front and back of the tricycle
frame.
·
Wheels will be fitted by
means of bolts, which will enable the installation of the lighting system
described above.
·
High-quality stainless
spokes and aluminium wheel rings will be used.
·
The design tricycle
dimensions are such that the tricycle fits through all standard doors.
·
The height of the driver's
seat and handlebars is electronically adjustable.
·
A 36 V/250 W brushless
electric motor will be installed. Motors of this type are maintenance-free
and, practically speaking, failure-free. Small energy consumption is their
advantage. Planetary gearing used in the tricycle makes riding without
additional resistance possible. After the battery has been isolated, a tricycle
with such a drive rides without an additional load [3].
·
The tricycle will be
equipped with a multi-function electronic LCD with the GPS satellite navigation
system. A BOSCH Nyon device may be a suggested
solution. The BOSCH Nyon navigation system can
display 2D and 3D maps. Text messages can be read and
incoming call numbers checked on a 4.3" display unit. The device is fully
waterproof and connected with the computer through a micro-USB port [2].
·
Easy replacement of the
single seat with a double seat, cargo bin or child's safety seat.
·
The planned range of the
tricycle with a fully-charged battery is from 20 to 50 km.
The basic tricycle dimensions are shown in
Fig. 5, and other technical parameters of the tricycle are as follows [12]:
·
wheel size:
front: 24", back: 26",
·
tricycle weight:
28 kg,
·
trolley load-bearing
capacity: 150 kg,
·
maximum saddle height: 852 mm.
Fig. 5.
Basic tricycle dimensions [12]
1 – basket
frame, 2 – 26" wheel,
3 – frame, 4 – photovoltaic
panel,
5 – guards, 6 – rivet set, 7 – metal guards
Visibility from the driver's level is not
limited because all trolley guards will be made of high-quality acrylic glass.
During a ride in the rain, guards improve the driver's visibility by protecting
his or her hands and face from rain, and raindrops rebound from the aerodynamic
guard structure, hence, do not fall on the driver. The driver's visibility will
not be impaired by persons sitting in the basket either, as it is designed in
such a way that the passenger's head is at the handlebar height. The seat is
equipped with a safety belt which protects the passenger from falling out
during the ride.
3. CONCLUSION
Statistical data presented
in this article show the possibility of dynamic development of both bicycles
touring and everyday bike use in the future. The wish to enjoy an active
lifestyle and admire nature enhances this situation. Poland's geographic
position is conducive to bicycle touring. Cycling routes diversified in terms
of the height profile, surroundings, etc., sometimes running across national
parks, are of particular interest to foreigners, who come gladly to spend
several days riding a bike.
It is, therefore, necessary
to reach out to cyclists and take care of appropriate infrastructure, which
also includes bikes, by suggesting new structural solutions for mass tourism.
Given many types of bikes available in the market, it is not easy to choose an
appropriate model.
The cost of the structural details of the
tricycle suggested in this article does vary considerably from standard
electric bikes, however, this solution has several important advantages, which
may be decisive in the purchase of this solution. The first advantage is the
possibility of continuous battery charging without the need to use charging
stations or plug the bike to electric sockets. Such a solution permits covering
long routes without appropriate infrastructure. The second advantage of the
tricycle is its dimensions, which are chosen in such a way that the tricycle
does not vary considerably from the clearance gauge of standard bikes. Owing to
that, the tricycle can be used on all cycling paths and parked at spaces
designed for standard bikes. Children, adults as well as persons with motor
dysfunctions may be transported in the tricycle, owing to which family tourism
may be practised.
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Received 05.07.2020; accepted in revised form 30.10.2020
Scientific
Journal of Silesian University of Technology. Series Transport is licensed
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