Patent Application
20110259189
The invention relates to a control device for a compressed air preparation device of a vehicle, a corresponding compressed air preparation device and to a method for controlling the compressed air preparation device.
A compressed air preparation device of a vehicle, in particular of a utility vehicle, is generally connected to a compressor which is driven directly by the engine. The compressor can be arranged directly on the engine shaft and therefore can always be driven when the engine is rotating or can be coupled to the engine via a clutch. In feed phases, the compressor feeds compressed air which firstly passes through an air dryer, which generally has a dry granulate as the desiccant and can, if appropriate, additionally carry out cleaning. The compressed air which is fed and dried is subsequently stored in a compressed air reservoir and can be output to consumer circuits, which can, for example, be brake control circuits of pneumatic brake systems and/or pneumatic ride level control devices with air bellows. In this context, the individual consumer circuits can firstly also have compressed air reservoirs.
In a feed phase or charging phase, the moisture content of the air dryer is therefore increased; and in order to avoid over-saturation of the desiccant and lower the degree of moisture thereof again, a portion of the dry compressed air which has been stored in the compressed air reservoir is fed back again via the air dryer in regeneration phases, and the compressed air which is therefore permeated with moisture is output, for example, to the surroundings. These regeneration phases generally occur directly subsequent to a feed phase, with the result that a fixed air flow rate or a specific portion of the previously fed air flow rate is always used for the regeneration. The initiation of these regeneration phases can take place in a purely mechanical fashion or else electrically by means of the control device.
The use of the air dryer therefore permits the compressed air system to be protected against damaging moisture, in particular also condensation overnight and, if appropriate, against the taken-up moisture freezing, with corresponding consequent damage.
Since the feed phase is associated with fuel consumption of the engine, in each case a certain amount of energy or a corresponding portion of the previously input fuel is used in the regeneration phases. Given differing load states, in particular also in the case of increased consumption of compressed air and therefore in the case of relatively long feed phases, in each case regeneration phases should be interposed where appropriate, and this is disadvantageous, in particular, in the case of relatively long use phases and feed phases.
EP 1 183 172 B1 describes a compressed air brake system in which, in overrun phases in which the movement energy of the vehicle drives the engine and the connected compressor, the compressed air reservoir is charged beyond the usual setpoint value since this additional feeding of compressed air takes place without additional consumption of fuel. As a result, the feed phases in which the engine drives the compressor while consuming fuel can be shortened to a corresponding degree or avoided, with the result that the overall fuel consumption can be reduced.
The invention is based on the object of providing a control device for a compressed air preparation device, such a compressed air preparation device, a vehicle system with a compressed air preparation device and a corresponding method for operating such a compressed air preparation device with which a relatively low fuel consumption value can be brought about and an appropriate compressed air flow rate is made available.
This object is achieved by means of a control device as claimed in claim 1, a compressed air preparation device as claimed in claim 14, a vehicle system as claimed in claim 15, a vehicle as claimed in claim 16 and a method as claimed in claim 17. The subclaims describe preferred developments.
According to the invention, it is therefore possible to carry out a management process of the engine load and/or of the generation of compressed air which includes the regeneration phases.
A management process of the engine load takes into account, in particular, the fuel consumption and can therefore determine phases with relatively low fuel consumption and relatively high fuel consumption (per distance travelled); in phases with a relatively low engine load it is possible for the desiccant to be excessively dried, i.e. to be set to a relatively low setpoint degree of moisture, with the result that no additional loading of the engine for the regeneration is necessary in phases with a relatively high engine load.
In particular, in this management process of the engine load overrun phases of the engine, that is to say phases in which the engine torque generated by the movement energy of the vehicle when the engine is coupled is higher than the engine torque requested by the driver by means of the accelerator pedal, can be used to feed compressed air via the engine and the compressor and to store it in the compressed air reservoir, with the result that some of this additionally fed compressed air can subsequently be used for the regeneration of the desiccant. As a result, the energy which is available in overrun phases without additional consumption of fuel can be used not only for the additional storage of compressed air but also for excessive drying of the air dryer.
The invention is based here on the recognition that in an overrun phase a portion of the movement energy of the vehicle can be stored in the form of excessive drying of the desiccant of the air dryer, since otherwise the drying of the desiccant is associated with a certain degree of fuel consumption.
According to the invention, in this context the excessive regeneration can be carried out not only in or after an overrun phase but also before the overrun phase if said phase is known in advance. In this way it is possible, where appropriate, for the compressed air reservoir to be emptied to below the otherwise relevant setpoint pressure (for example to above a minimum reserve value) by an additional regeneration phase, since cost-effective charging is subsequently possible in the overrun phase.
Through the targeted planning of the generation of compressed air it is possible for route sections of the route with a relatively high compressed air consumption value to be determined in advance, and for excessive regeneration and, if appropriate, additionally charging of the compressed air reservoir to a relatively high setpoint pressure to be carried out in advance in order to subsequently permit relatively long feed phases and use phases.
According to the invention, it is possible to carry out adjustment to a setpoint degree of moisture, wherein the setpoint degree of moisture is determined by the control device, and an actual value and/or current value is either determined directly by means of a measurement signal of a moisture sensor or is determined indirectly or estimated from the time periods of the last feed phases and regeneration phases. With such adjustment it is therefore possible for the control device to define the setpoint degrees of moisture as a function of the current or future values of the engine load or of the consumption of compressed air.
The invention therefore makes it possible to save fuel. Furthermore, relatively long feed phases or even use phases which persist for a relatively long time and a relatively high air consumption with relatively few or short regeneration phases are possible. As a result, the regeneration phases can be delayed or shortened. This leads, inter alia, to a quieter control behavior and to fewer gearshifting processes, in particular relatively long feed phases are also made possible. Furthermore, the components can, if appropriate, be given smaller dimensions.
The route sections with differing compressed air consumption and/or differing engine load can already be determined in advance. This can be done, on the one hand, on the basis of map data or route data relating to the route in advance as well as position data, wherein the position data can be formed, for example, by means of a global position determining system (GPS) and/or a route counter (kilometer counter) of the vehicle. In this way, route profiles or route-dependent feed profiles and/or route-dependent consumption profiles of the compressed air are produced. Said profiles can also be determined adaptively or on a self-learning basis, as an addition to or alternative to the determination on the basis of map data, when the vehicle travels through the respective route repeatedly, for example in the case of a scheduled bus or a truck which is used on a shuttle basis between two fixed points. In principle, adaptive systems can be formed not only for identical routes but also for similar routes, for which purpose the route profiles which are determined can be compared with one another and evaluated qualitatively.
The route profiles can be assigned not only to the respective route but also on an additional basis to time data, in particular times of day, in order to define the differing traffic load at the various times of day, in particular in the morning, at midday, in the afternoon, in the evening and at night. In addition, it is also possible, for example, to define days of the week. Furthermore, the route profiles which are determined can be continuously updated by corresponding formation of mean values in order also to take into account temporary changes as a result, for example, of roadworks, obstructions, etc.
According to the invention, a vehicle energy management system which can flexibly optimize the energy consumption on a respectively up-to-date basis can therefore be formed.
The control device according to the invention implements switching over to a regeneration phase or lengthening of an existing regeneration phase by outputting corresponding control signals, in particular to the valve devices for the setting of the respective phases. The method according to the invention corresponds to the application of the control device according to the invention.
One advantage of the invention is that future previously known vehicle states can be approached with increased air consumption, for example unhitching of semitrailers, shunting, stopping points with already over-regenerated desiccants, with the result that these situations are not impeded or delayed by the regeneration of the desiccant. As a result, the compressed air supply is improved and therefore the maneuvering time of the vehicle reduced and/or the vehicle manufacturer can equip the vehicle with smaller pressure reservoirs and therefore save costs and space on the vehicle frame.
The invention will be explained below using a number of embodiments and with reference to the appended drawings, in which:
A compressed air preparation device 1 of a utility vehicle 2 with a vehicle engine 10 and pneumatic brakes and air springs has, according to
An air dryer 6, in which a desiccant 6a, for example a drying granulate, is accommodated, is connected to the outlet of the compressor 4. A compressed air feed path 17 with a four-circuit protection valve 7 is connected to the outlet 6b of the air dryer 6 via a non-return valve 16, said four-circuit protection valve 7 having, for example, four overflow valves 7a, 7b, 7c, 7d and in turn having compressed air reservoirs 8, 18, 28, 38 of the four connected consumer circuits connected thereto; for example the container 8 here is provided for a service brake circuit I, the container 18 is provided for a service brake circuit II, the container 28 for a trailer brake circuit and/or a parking brake circuit, and the container 38 is provided for a secondary consumer circuit. In each case a pressure limiting valve 7e and 7f can be advantageously provided upstream of the containers 28 and 38. Pressure sensors 8a, 18a, 28a, which output output signals p1, p2, p3 to the control device 3, are provided in the containers 8, 18, 28 or on the compressed air feed line to these containers.
Furthermore, a non-return valve 9 is connected to the outlet 6b of the air dryer 6 in the closing direction, and an orifice 20, which is adjoined by a regeneration path 21 which is therefore closed when the compressor 10 is operating, is connected. A venting valve (scavenging valve) 5, which is configured as a 2/2-way valve, is connected between the outlet of the compressor 4 and a sound damper 22 which serves as compressed air outlet; said 2/2-way valve has a pneumatic control inlet 5a which is connected to the regeneration path 21 and switches over from the closed position shown to the open position when pressure is applied.
Furthermore, a compressor control solenoid valve 23 which is embodied as a 3/2-way valve is connected between a pneumatic control inlet 4a of the compressor 4 and the sound damper 22. In its shown position of rest, the control inlet 4a is therefore pressureless; when the compressor control solenoid valve 23 is actuated by means of the control device 3, it connects the feed path 17 to the control inlet 4a, with the result that the compressor 4 is switched off. A regeneration control solenoid valve 24 is likewise embodied as a 3/2-way valve and is connected between the regeneration path 21 and the sound damper 22. In its non-energized basic state, said regeneration control solenoid valve 24 therefore connects the regeneration path 21 to the sound damper 22, with the result that the regeneration path 21 is pressureless, and when its control inlet is energized by the control device 3 it switches over and connects the regeneration path 21 to the feed path 17.
In a customary embodiment of a compressed air preparation device, some of the aforesaid components can expediently be combined to form one structural unit. For example, an electronic compressed air preparation device 1 according to the invention is implemented as a structural unit with the components 3, 5, 6, 7, 8a, 9, 12, 16, 17, 18a, 20, 21, 22, 23, 24, 28a. This compressed air preparation device 1 forms one vehicle system 30 together with the compressor 4 and the compressed air containers 8, 18, 28, 38.
In a feed phase (or charging phase), the compressor 4 feeds compressed air to the compressed air containers 8, 18, 28, 38 through the air dryer 6 and the four-circuit protection valve 7.
In a regeneration phase, the control device 3 actuates the regeneration control solenoid valve 24, with the result that the latter switches over and outputs compressed air from the compressed air reservoirs 8, 18, 28, 38 to the regeneration path 21 via the four-circuit protection valve 7 and the feed path 17. Furthermore, the control device 3 switches over the compressor control solenoid valve 23, with the result that said compressor control solenoid valve 23 applies compressed air to the control inlet 4a of the control device 4 and therefore switches off the latter. Furthermore, the venting valve 5 is automatically switched over by the regeneration path 21 which is under pressure, and said venting valve 5 therefore connects the compressor outlet or the inlet of the air dryer 6 to the sound damper 22, with the result that the latter are pressureless. Since in this way the outlet 6a of the air dryer 6 is also pressureless, the non-return valve 9 connects through, with the result that when the non-return valve 16 closes the air dryer 6 is scavenged in the regeneration direction toward the sound damper 22 and therefore to the surroundings.
As a result, in the feed phase the compressed air which is taken up is dried in the air dryer 6 (and, if appropriate, cleaned), as a result of which the degree of moisture in the air dryer 6 rises. In the regeneration phase, the moisture which is taken up in the air dryer 6 is output again entirely or partially.
The control device 3 can compare current pressure values determined from the pressure signals p1, p2, p3 with a setpoint pressure ps, and when a limiting value is undershot it can, if appropriate, switch over from a regeneration phase to a feed phase. Furthermore, a moisture sensor 12 can be provided, for example, in the air dryer 6 or in a line which is connected to the air dryer 6, which outputs a measurement signal f of the degree of moisture to the control device 3. However, such a moisture sensor 12 is basically not necessary since the control device 3 can also automatically estimate the moisture content of the air dryer 6, for example from the time period of the previous feed phases and regeneration phases, the engine speed and other vehicle data.
According to the invention, the moisture content of the air dryer 6 is set not only on the basis of the current moisture content which is determined or estimated but additionally as a function, firstly, of the engine load, in particular of the available kinetic energy of the vehicle 2 and/or secondly of an anticipated compressed air demand.
In the case of a management process as a function of the engine load, the compressor 4 is driven in time periods or in route sections with a low engine load in order to charge all, or some of, the pressure reservoirs 8, 18, 28, 38 with a higher pressure than a conventional setpoint pressure. Such phases are, in particular, overrun phases Ts of the utility vehicle 2 or of its engine 10 in which the thrust torque applied to the engine 10 via the kinetic energy of the utility vehicle 2 when the engine clutch is engaged is greater than an engine torque which is requested from the driver or from a vehicle movement dynamics control system. Such overrun phases Ts can be, in particular, downhill travel by the utility vehicle 2 and/or braking processes. Braking of the utility vehicle 2 by means of the engine and the connected compressor 4 is therefore brought about and in a feed phase a relatively high setpoint pressure ps is set at some or all of the pressure reservoirs 8, 18, 28, 38 and therefore charges the latter excessively, but the pressure p remains below an upper safety limiting value. Overrun phases can be respectively determined on an up-to-date basis from a throttle valve position of the engine 10 and/or an accelerator pedal activation and/or a data signal which describes the engine torque, on the vehicle bus of the vehicle 2.
The additionally stored compressed air can, on the one hand, be used by means of the consumer circuits which are connected to the compressed air reservoirs 8, 18, 28, 38. According to the invention, this additionally stored compressed air, or a portion thereof, can additionally also be used for excessive drying of the desiccant 6a. In this way, a setpoint moisture value is lowered and in regeneration phases the degree of moisture f is lowered further than in other phases. Although this excessive drying is possibly not expedient in other phases compared to the compressed air flow rate necessary here or the energy corresponding to the compressed air flow rate, since the effectiveness or the further discharging of moisture by means of the introduced compressed air decreases as the degree of moisture decreases, the invention recognizes that in any case there is an excess of kinetic energy available, and this kinetic energy or a portion of this kinetic energy can therefore be stored in the form of excessive drying of the desiccant of the air dryer 6.
According to one advantageous development, the relevant time periods or route sections with a low engine load or with overrun conditions can already be determined in advance. According to one variant, this is possible by recording map data K and position data GPS which are determined by a GPS system of the utility vehicle 2. As a result, the control device 3 and/or a further device, interacting with the control device 3, of the control system according to the invention can determine predicted overrun phases Ts and implement in them the inventive excessive drying of the desiccant 6a. On the basis of the map data K it is possible, where appropriate, to detect negative gradient sections with a not excessive negative gradient, a transition from a freeway or expressway to relatively slow roads as well as the end section before the destination B as overrun phases.
As an alternative to or in addition to the determination of the route sections with a low engine load on the basis of map data it is also possible to determine the latter adaptively or in a self-learning fashion when the utility vehicle 2 repeatedly travels over routes or parts of routes. This is advantageous, in particular, in the case of scheduled buses and trucks, for example trucks used in shuttle transportation, which travel regularly along certain ends of routes.
According to the invention, it is also possible to determine in advance not only route sections with a different engine load but also route sections with a different compressed air demand. These route sections can, in particular, be downhill journeys with a relatively high negative gradient and Stop-and-Go sections in which there is a relatively high braking demand. Furthermore, it is possible, for example, to estimate the end phase of the route as a time period with an increased compressed air demand which occurs as a result of braking, decoupling of a semitrailer, coupling of a semitrailer and jackknifing operations in coaches. Furthermore, it is advantageously detected when the vehicle is parked with a relatively large stored quantity of compressed air or a relatively high air pressure in some or all of the compressed air reservoirs 8, 18, 28, 38 so that during the subsequent journey this compressed air is available again in order to correspondingly pressurize the consumer circuits and, if appropriate, carry out ride level control processes. In this way, at the end of the journey a maximum pressure is aimed at in one, some or all of the compressed air reservoirs 8, 18, 28, 38 and, on the other hand, a very low degree of moisture in the air dryer 6 is aimed at.
This determination of the route sections with a compressed air demand which is expected to be increased can, according to the above statements, also be carried out on the basis of the map data K and position data GPS and/or adaptively. In particular, the end of the journey is often input directly into the GPS control system and is therefore known.
According to the invention, a self-learning vehicle energy management system can provide profiles of the engine load and/or of the compressed air consumption not only for the same recurring routes but also for routes which are detected as being similar or equivalent. In this context, for example a route profile with corresponding positive gradients and negative gradients and/or a classification as an inner city, country road or freeway are produced, and a consumption profile (power requirement profile) and/or a regeneration profile are assigned to this sequence of the different areas. The energy management system according to the invention uses this information to optimize the energy flow between the generating elements, i.e. the engine 10 together with the compressor 4, the consumers of the connected consumer circuits and in one, some or all of the compressed air reservoirs 8, 18, 28, 38 and the air dryer 6 which is evaluated according to the invention as being a device for storing an energy equivalent. The air dryer 6 is therefore also considered according to the invention to be a type of “energy store” and is functionally integrated since by means of excessive drying an energy equivalent is provided when the energy necessary for this is sufficiently present in the system or present in the system in excess.
Owing to the stored data and the estimation of the consumption profile and/or of the feed profile it is therefore possible according to the invention to decide how, on the one hand, one, more or all of the compressed air reservoirs 8, 18, 28, 38 are charged or recharged and, on the other hand, the moisture state of the air dryer 6 is set.
The production of the profiles in an adaptive method can be carried out by using minimum values, maximum values and average values from the different journeys. Through recurrent journeys it is possible to respectively improve the profile and adapt it to the changing ambient conditions, for example using sliding average values. It is therefore possible, for example, also to sense traffic jams as a result of temporary roadworks.
According to the invention, times of day and/or days of the week can be additionally assigned to the route profiles.
Furthermore, for the determination of the route profiles, information relating to the charge state or the mass of the utility vehicle 2, which is partially already available on the vehicle-internal databus, can be used to estimate the consumption profile and/or the regeneration profile of the route even better.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 056 322.6 | Nov 2008 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/005778 | 8/8/2009 | WO | 00 | 6/13/2011 |
