Patent Publication Number: US-2023144112-A1

Title: Electronic brake for vehicle and control method therefor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2021-0151793, filed on Nov. 5, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to an electronic brake for a vehicle and a control method therefor. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     An electronic brake forms a braking force for a wheel brake mechanism using a motor. A brake device including a motor pressurizes a working fluid within a hydraulic circuit of the electronic brake. The pressurized working fluid is selectively carried to a plurality of wheel brake mechanisms through a flow pathway which is formed by opening and closing a plurality of valves on the hydraulic circuit of the electronic brake. The plurality of wheel brake mechanisms slows down or stops wheels by using a hydraulic pressure of the carried working fluid. 
     An auxiliary brake device was proposed which is configured to generate a braking pressure by serving as a backup for a main brake device of a vehicle when a failure occurs to the main brake device. As a backup for a main controller for controlling the main brake device, an auxiliary controller for controlling the auxiliary brake device may be mounted along with the auxiliary brake device. The auxiliary brake system is configured to go into cooperative control, if the power output of the main brake device does not meet a set condition. Here, the phrase “the power output of the main brake device does not meet a set condition” may mean that something abnormal occurs to the main brake device. 
     However, even with an auxiliary brake device, a brake device for a vehicle is not able to generate a braking force required to safely run the vehicle, if an abnormality occurs to the auxiliary brake device. 
     SUMMARY 
     According to at least one aspect, the present disclosure provides a control method for an electronic brake for a vehicle, the electronic brake comprising a first braking device configured to supply hydraulic pressure to wheel brakes, a second braking device including a pump, that is connected between at least part of the wheel brakes and the first braking device and configured to fluidically disconnect an oil reservoir and an outlet of the pump when a brake pedal is pressed a predetermined distance or greater, and a control unit including a first controller for controlling the first braking device and a second controller for controlling the second braking device, the method comprising: determining, by the control unit, whether something is wrong with the first braking device; based on a determination that something is wrong with the first braking device, determining, by the control unit, whether something is wrong with a blocking valve unit mounted to the second braking device and connected between the oil reservoir and the outlet of the pump; and based on a determination that something is wrong with the blocking valve unit, controlling the first braking device by the first controller so that a flow path on the first braking device connecting the oil reservoir and the outlet of the pump is closed. 
     According to another aspect, the present disclosure provides an electronic brake for a vehicle, the electronic brake comprising a first braking device configured to supply hydraulic pressure to wheel brakes, a second braking device including a pump, that is connected between at least part of the wheel brakes and the first braking device and configured to fluidically disconnect an oil reservoir and an outlet of the pump when a brake pedal is pressed a predetermined distance or greater, and a control unit for controlling the first braking device and the second braking device, the control unit comprising: a first determining unit which determines whether something is wrong with the first braking device; a second determining unit which, based on a determination that something is wrong with the first braking device, determines whether something is wrong with a blocking valve unit mounted to the second braking device and connected between the oil reservoir and the outlet of the pump; a first controller which, based on a determination that something is wrong with the blocking valve unit, controls the first braking device so that a flow path on the first braking device connecting the oil reservoir and the outlet of the pump is closed; and a second controller which controls the second braking device so that the second braking device generates a required braking force. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a hydraulic circuit diagram of an electronic brake for a vehicle according to an embodiment of the present disclosure. 
         FIG.  2    is a sequence diagram of a control method according to an embodiment of the present disclosure. 
         FIG.  3    is a block diagram schematically showing a configuration of an electronic brake for a vehicle according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic brake for a vehicle and a control method therefor according to an embodiment of the present disclosure are able to generate a braking force required to safely run the vehicle even if something is wrong with a main brake device, by controlling an auxiliary brake device, which generates a required braking force by serving as a backup for the main brake device. 
     Furthermore, an electronic brake for a vehicle and a control method therefor according to an embodiment of the present disclosure are able to generate a braking force required to safely run the vehicle in a double failure situation, by controlling the main brake device by a control unit so that the main brake device delivers a hydraulic pressure formed by the auxiliary brake device to wheel brakes if something is wrong with the main brake device and the auxiliary brake device. 
     The aspects of the present disclosure are not limited to the foregoing, and other aspects not mentioned herein will be able to be clearly understood by those skilled in the art from the following description. 
     Hereinafter, some exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, like reference numerals preferably designate like elements, although the elements are shown in different drawings. Further, in the following description of some embodiments, a detailed description of known functions and configurations incorporated therein will be omitted for the purpose of clarity and for brevity. 
     Additionally, various terms such as first, second, A, B, (a), (b), etc., are used solely to differentiate one component from the other but not to imply or suggest the substances, order, or sequence of the components. Throughout this specification, when a part ‘includes’ or ‘comprises’ a component, the part is meant to further include other components, not to exclude thereof unless specifically stated to the contrary. The terms such as ‘unit’, ‘module’, and the like refer to one or more units for processing at least one function or operation, which may be implemented by hardware, software, or a combination thereof. 
       FIG.  1    is a hydraulic circuit diagram of an electronic brake for a vehicle according to an embodiment of the present disclosure. 
     In this disclosure, the terms “front” and “rear” refer to the direction in which a brake pedal  112  is pressurized and the opposite direction thereof, respectively. In this disclosure, front wheel brakes w 3  and w 4  and rear wheel brakes w 1  and w 2  refer to wheel brakes mounted to front wheels and wheel brakes mounted to rear wheels, respectively. 
     Referring to  FIG.  1   , an electronic brake for a vehicle that is controlled by a control method according to an embodiment of the present disclosure includes all or part of an oil reservoir  130 , a first braking device  110 , a second braking device  120 , wheel brakes w 1  to w 4 , and a control unit  150 . 
     The wheel brakes w 1  to w 4  are devices that are configured to be mounted to wheels and apply a braking force to the wheels. The wheel brakes w 1  to w 4  may be caliper-type brakes or drum-type brakes, for example. The wheel brakes w 1  to w 4  are configured to be supplied with hydraulic pressure from the first and/or second braking device  110  and/or  120  and restrict the rotation of the wheels. 
     The oil reservoir  130  is installed to store working fluid or supply it to a hydraulic circuit. The fluid in the oil reservoir  130  may be supplied to a master cylinder  111  or a pump  121 , and the fluid may be pressurized in the master cylinder  111  or the pump  121 . The pressurized fluid may be selectively delivered to a plurality of wheel brakes w 1  to w 4  by a plurality of valves mounted on the first braking device  110  and the second braking device  120 . 
     The first braking device  110  is configured to supply hydraulic pressure to the wheel brakes w 1  to w 4 . The first braking device  110  is connected between the oil reservoir  130  and the wheel brakes w 1  to w 4 . The master cylinder  111  included in the first braking device  110  may pressurize fluid, and the pressurized fluid may be delivered to the wheel brakes w 1  to w 4 . 
     The master cylinder  111  includes a piston  111   a  configured to pressurize fluid inside of it. An inlet of the master cylinder  111  is communicated to the oil reservoir  130 , and an outlet of the master cylinder  111  is communicated to the wheel brakes w 1  to w 4 . The fluid introduced from the oil reservoir  130  to the master cylinder  111  may be pressurized within the master cylinder  111  and delivered to the wheel brakes w 1  to w 4 . The master cylinder  111  may have two chambers divided by a piston  111   a . The chamber positioned at the front of the piston  111   a  is referred to as a first chamber  111   b , and the chamber positioned at the rear of the piston  111   a  is referred to as a second chamber  111   c . The first chamber  111   b  and the second chamber  111   c  each may be connected to different wheel brakes w 1  to w 4 . The first chamber  111   b  for the control method according to an embodiment of the present disclosure is connected to the wheel brakes w 1  to w 4  mounted to the rear wheels of the vehicle, and the second chamber  111   c  therefor is connected to the wheel brakes w 1  to w 4  mounted to the front wheels of the vehicle. Here, a flow path connecting the first chamber  111   b  and the wheel brakes w 1  to w 4  mounted to the rear wheels of the vehicle is referred to as a rear wheel flow path. A flow path connecting the second chamber  111   c  and the wheel brakes w 1  to w 4  mounted to the front wheels of the vehicle is referred to as a front wheel flow path. The rear wheel flow path and the front wheel flow path may be configured to be fluidically communicated or disconnected depending on whether a connection valve  114  is open or closed. 
     The first braking device  110  may include a switch valve unit  115  mounted on a flow path connecting the inside of the master cylinder  111  and the oil reservoir  130 . When the switch valve unit  115  is opened, the master cylinder  111  and the oil reservoir  130  are communicated and a hydraulic pressure in the master cylinder  111  is reduced. 
     The piston  111   a  may be configured to slide in a direction in which it pressurizes the fluid in the master cylinder  111  as the driver pushes the pedal  112 . Although not shown in  FIG.  1   , the master cylinder  111  may include an electronic booster that is configured to move the piston  111   a  based on a brake signal generated by a pedal stroke sensor, when the driver pushes the pedal  112 . When the hydraulic pressure in the second chamber  111  positioned at the front of the piston  111   a  is reduced, the reaction force exerted on the piston  111   a  by the hydraulic pressure in the second chamber  111   c  is reduced when the piston  111   a  is pressurized. Accordingly, the force the driver applies to the brake pedal  112  to move the piston  111   a  forward is reduced. 
     The piston  111   a  has a predetermined thickness in the direction of movement. The second chamber  111   c  and the wheel brakes w 1  to w 4  mounted to the rear wheels may be fluidically communicated or disconnected depending on the amount of stroke of the piston  111   a . Referring to  FIG.  1   , when the piston  111   a , is pressed a predetermined distance or greater, an outlet made through the chamber  111   c  is closed by the outer periphery of the piston  1111   a . In this way, the wheel brakes w 1  to w 4  mounted to the front wheels and the second chamber  111   c  are fluidically disconnected. 
     The second braking device  120  is connected between at least part of the wheel brakes w 1  to w 4  and the first braking device  110 . The second braking device  120  is configured to generate a required braking force by serving as a backup for the first braking device  110 , when something is wrong with the first braking device  110 . Here, the required braking force is a value that is determined based on the amount of pedal stroke from the driver measured by the pedal stroke sensor, and may mean a braking force equivalent to the driver&#39;s intention to slow down or stop the vehicle. On the other hand, the required braking force may mean a braking signal calculated by the autonomous driving system of the vehicle. The second braking device  120  may be disposed in such a way as to supply hydraulic pressure to the front wheel brakes w 3  and w 4 . The electronic brake for a vehicle according to an embodiment of the present disclosure is configured to deliver fluid to the oil reservoir  130 , the first braking device  110 , the second braking device  120 , and the front wheel brakes w 3  and w 4 , sequentially. 
     The pump  121  included in the second braking device  120  may produce a hydraulic pressure for generating the required braking force. An inlet of the pump  121  may be connected to the oil reservoir  130 , and an outlet of the pump  121  may be connected to the wheel brakes w 1  to w 4 . An inlet flow valve unit  126  may be mounted on a flow path connecting the inlet of the pump  121  and the oil reservoir  130 . When the inlet flow valve unit  126  is opened, fluid may be supplied to the pump  121  from the oil reservoir  130 . If the second braking device  120  needs to increase brake pressure by serving as a backup for the first braking device  110 , fluid may be delivered to the pump  121  from the oil reservoir  130 , and the delivered fluid may be pressurized within the pump  121  and delivered to the wheel brakes w 1  to w 4 . The second braking device  120  may be configured such that the oil reservoir  130  and the outlet of the pump  121  are fluidically disconnected when the brake pedal  112  is pressed a predetermined distance or greater. The second chamber  111   c  may be configured to be communicated to the oil reservoir  130  and the second braking device  120 . With this configuration, when the piston  111   a  is pressed a predetermined distance or greater, an outlet of the second chamber  111   c  leading to the second braking device  120  may be closed by the outer periphery of the piston  111   a . Accordingly, a high-pressure fluid pressurized in the second braking device  120  leaks into the oil reservoir  130 , thereby preventing a reduction in the pressure of the fluid. 
     The second braking device  120  includes all or part of a blocking valve unit  125 , an inlet valve unit IV, and an outlet valve unit OV. The block valve unit  125  is connected between the oil reservoir  130  and the wheel brakes w 1  to w 4 . The blocking valve unit  125  is connected between the oil reservoir  130  and the outlet of the pump  121 . When the blocking valve unit  125  is closed, a high-pressure fluid discharged from the outlet of the pump  121  is kept from being delivered to the oil reservoir  130 . Accordingly, the pressure of the fluid pressurized in the pump  121  may be transferred to the wheel brakes w 1  to w 4 . The inlet valve unit IV is mounted on a flow path connecting the outlet of the pump  121  and the wheel brakes w 1  to w 4 . The inlet valve unit IV may be configured as a normal open-type solenoid valve which is closed when no current is applied to it. The control unit  150  may control the inlet valve unit IV to open and the outlet valve unit OV to close so that the hydraulic pressure formed in the first and second braking devices  110  and  120  is transferred to the wheel brakes w 1  to w 4 . On the other hand, the control unit  150  may control the inlet valve unit IV to close and the outlet valve unit OV to open so that the hydraulic pressure of the wheel brakes w 1  to w 4  is reduced. 
       FIG.  2    is a sequence diagram of a control method according to an embodiment of the present disclosure. 
     The control method according to an embodiment of the present disclosure may be performed by the electronic brake for a vehicle illustrated in  FIG.  1   . 
     Referring to  FIGS.  1  and  2   , the electronic brake for a vehicle includes the control unit  150 . The control unit  150  includes a first controller  151  for controlling the first braking device  110  and a second controller  152  for controlling the second braking device  120 . The control unit  150  determines whether something is wrong with the first braking device  110  (S 210 ). The first controller  151  may determine whether something is wrong with the first braking device  110 , based on a measurement from a pressure sensor mounted on the first braking device  110  or the value of a current applied to a valve mounted on the first braking device  110 . For example, if a pressure measured by the pressure sensor is not high enough to be equivalent to the required braking force, the control unit  150  may determine that something is wrong with the first braking device  110 . If there isn&#39;t something wrong with the first braking device  110 , the control method of the present disclosure is completed. 
     If it is determined that something is wrong with the first braking device  110 , the second controller  152  determines whether something is wrong with the blocking valve unit  125  (S 230 ). Specifically, the second controller  152  may determine whether the blocking valve unit  125  gets stuck while opening. If something is wrong with the first braking device  110 , the second controller  152  may control the second braking device  120  so that the second braking device  120  generates the required braking force by serving as a backup for the first braking device  110 . If the blocking valve unit  125  gets stuck while opening, a high-pressure fluid pressurized in the second braking device  120  leaks into the oil reservoir  130 , and the second braking device  120  is therefore unable to generate the required braking force by serving as a backup for the first braking device  110 . The control method for the electronic brake for a vehicle allows the electronic brake for a vehicle to produce the required braking force by using the following control method even in a double failure situation (hereinafter, in the event of a double failure). 
     If it is determined that something is wrong with the blocking valve unit  125  in S 230 , the first controller  151  controls the first braking device  110  so that a flow path on the first braking device  110  that connects the oil reservoir  130  and the outlet of the pump  121  is closed (S 250  to S 290 ). 
     In the step S 250 , the first controller  151  determines whether the driver is pressing the brake pedal  112 . The first controller  151  may determine whether the driver is pressing the brake pedal  112  or not, upon receiving a signal related to the amount of stroke of the brake pedal  112  from the pedal stroke sensor connected to the brake pedal  112 . If it is determined that the driver is pressing the brake pedal  112 , the first controller  151  controls the first braking device  110  so as to reduce a hydraulic pressure in the master cylinder  111 . The control unit  150  controls the first and second braking devices  110  and  120  so that the first and second braking devices  110  and  120  produce a required braking force equivalent to the amount of pedal stroke from the driver, under a circumstance in which something is wrong with the first braking device  110  and the blocking valve unit  125 . 
     In the step S 260 , the first controller  151  controls the switch valve unit  115  so that the switch valve unit  115  is opened, Once the switch valve unit  115  is opened, the hydraulic pressure in the master cylinder  111  is reduced. Accordingly, the reaction force exerted on the piston  111   a  by the fluid in the master cylinder  111  is reduced, making it possible to move the piston  111   a  forward by a small force. Once the piston  111   a  is moved forward a predetermined distance or greater, the oil reservoir  130  and the outlet of the pump  121  are fluidically disconnected. As such, the fluid pressurized by the pump  121  of the second braking device  120  may be delivered to the wheel brakes w 1  to w 4  without leaking into the oil reservoir  130 . By using the control method according to the step S 260 , it is possible for the second braking device  120  to transfer the braking force it produces by serving as a backup for the first braking device  110  to the wheel brakes w 1  to w 4 , when the driver presses the brake pedal  112  with a small force in the event of a double failure. 
     In the step S 270 , the control unit  150  determines whether to increase the braking force applied to the vehicle by the electronic brake for the vehicle. If the required braking force is greater than a current braking force which is calculated based on a pressure measured by a hydraulic sensor connected to the wheel brakes w 1  to w 4 , the control unit  150  may determine that the braking force needs to be increased. For example, if a hydraulic pressure formed in the master cylinder  111  by the driver&#39;s pedal pressure is not high enough to be equivalent to the required braking force, this may mean that the required braking force is greater than the current braking force. The second braking device  120  may form a braking force as a backup for the pedal pressure from the driver. 
     If it is determined that the braking force needs to be increased in the step S 270 , the second controller  152  controls the inlet flow valve unit  126  so that the inlet flow valve unit  126  mounted on the flow path connecting the oil reservoir  130  and the inlet of the pump  120  is opened (S 290 ). Moreover, the second controller  152  controls the pump  121  so that the pump  121  pressurizes fluid. As such, the fluid enters the pump  121  from the oil reservoir  130 , and the fluid is pressurized in the pump  121 . The pressurized fluid may be delivered to the wheel brakes w 1  to w 4  without leaking to the oil reservoir  130  in the step S 260 . 
     On the other hand, if it is determined that the braking force does not need to be increased in the step S 270 , the second controller  152  controls the open and closed states of the inlet valve unit IV and the outlet valve unit OV (S 280 ). That is, the control unit  150  may perform control of ABS (anti-lock brake system), TCS (traction control system), and so on. 
     If it is determined that there isn&#39;t something wrong with the blocking valve unit  125  in the step S 230  the second controller  152  controls the second braking device  120  so that the second braking device  120  generates a hydraulic pressure equivalent to the required braking force (S 240 ). That is, the second braking device  120  produces a braking pressure by serving as a backup for the first braking device  110 . 
     If it is determined that something is wrong with the first braking device  110  in the step S 210 , the control unit  150  may control an electronic parking brake mounted on the rear wheels so that the electronic parking brake applies a braking force to the rear wheels (S 220 ). The second braking device  120  supplies hydraulic pressure to the front wheel brakes w 3  and w 4  by supplementing some of the functions of the first braking device  110 , and the electronic parking brake supplies hydraulic pressure to the rear wheel brakes w 1  and w 2  by supplementing other functions of the first braking device  110 . 
     According to the control method according to an embodiment of the present disclosure, if something is wrong with the first braking device  110 , the second braking device  120  and/or the electronic parking brake may produce a required braking force. Moreover, in the event of a double failure where the first braking device  110  and part of the components of the second braking device  120  fail, part of the components of the first braking device  110  and the second braking device  120  may be controlled so that the electronic brake for the vehicle produces the required braking force. 
       FIG.  3    is a block diagram schematically showing a configuration of an electronic brake for a vehicle according to an embodiment of the present disclosure. 
     The electronic brake for a vehicle according to an embodiment of the present disclosure may be an electronic brake for a vehicle that is controlled by the above-described control method. Thus, redundant description will be omitted. 
     Referring to  FIGS.  1  and  3   , the electronic brake for a vehicle includes all or part of a first braking device  110 , a second braking device  120 , and a control unit  150 . The first braking device  110  is configured to supply hydraulic pressure to the wheel brakes w 1  to w 4 . The second braking device  120  is connected between at least part of the wheel brakes w 1  to w 4  and the first braking device  110 . The first braking device  110  may include a master cylinder  111  having a piston  111   a  configured to be pressed along with a brake pedal  112 . The first braking device  110  may include a switch valve unit  115 . The switch valve unit  115  is mounted on a flow path connecting the inside of the master cylinder  111  and an oil reservoir  130 . The second braking device  120  includes a pump  121 . When the brake pedal  112  is pressed a predetermined distance or greater, the oil reservoir  130  and an outlet of the pump  121  are fluidically disconnected. The control unit  150  controls the first braking device  110  and the second braking device  120 . The second braking device  120  includes a blocking valve unit  125  connected between the oil reservoir  130  and the outlet of the pump  121 . 
     The control unit  150  includes a first determining unit  153 , a second determining unit  154 , a first controller  151 , and a second controller  152 . According to an exemplary embodiment of the present disclosure, the control unit  150  may include a processor (e.g., computer, microprocessor, CPU, ASIC, circuitry, logic circuits, etc.) and an associated non-transitory memory storing software instructions which, when executed by the processor, provides the functionalities of the first determining unit  153 , the second determining unit  154 , the first controller  151 , and the second controller  152 . Herein, the memory and the processor may be implemented as separate semiconductor circuits. Alternatively, the memory and the processor may be implemented as a single integrated semiconductor circuit. The processor may embody one or more processor(s). 
     The first determining unit  153  determines whether something is wrong with the first braking device  110 . The first determining unit  153  may determine whether something is wrong with the first braking device  110 , based on pressure information and the like received from a pressure sensor or the like of the first braking device  110 . Upon determining that something is wrong with the first braking device  110 , the first determining unit  153  sends a first failure signal. 
     The second determining unit  154  receives the first failure signal. Upon receiving the failure signal, the second determining unit  154  determines whether something is wrong with the blocking valve unit  125 . Specifically, the second determining unit  154  may determine whether the blocking valve unit  125  gets stuck while opening. The second determining unit  154  may determine whether something is wrong with the blocking valve unit  125 , by using a pressure measurement from a pressure sensor (not shown) mounted on a flow path of the blocking valve unit  125  on the side of the first braking device  110 . Upon determining that something is wrong with the blocking valve unit  125 , the second determining unit  154  may send a second failure signal. 
     The first controller  151  controls the first braking device  110 . When the first controller  151  receives a blocking valve failure signal, the first controller  151  may control the first braking device  110  so that a flow path on the first braking device  110  connecting the oil reservoir  130  and the outlet of the pump  121  is closed. Specifically, the first controller  151  may control the first braking device  110  in such a way that the switch valve unit  115  is opened. 
     The second controller  152  controls the second braking device  120 . The second controller  152  may include a third determining unit  152   a . Upon receiving the first failure signal and/or the second failure signal, the third deterterming unit  152   a  determines whether the braking force applied to the vehicle by the electronic brake for the vehicle needs to be increased. If the third determining unit  152   a  determines that the braking force needs to be increased, the second controller  152  controls the inlet flow valve unit  126  to open and drives the pump. Here, the inlet flow valve unit  126  is a valve that is mounted on a flow path connecting the oil reservoir  130  and an inlet of the pump  121 . 
     With this configuration, the electronic brake for a vehicle according to an embodiment of the present disclosure is able to produce a braking force stably even in the event of a failure where the blocking valve unit  125  gets stuck. 
     An electronic brake for a vehicle and a control method therefor according to an embodiment of the present disclosure have the effect of generating a braking force required to safely run the vehicle even if something is wrong with a main brake device, by controlling an auxiliary brake device, which generates a required braking force by serving as a backup for the main brake device. 
     Furthermore, an electronic brake for a vehicle and a control method therefor according to an embodiment of the present disclosure have the effect of generating a braking force required to safely run the vehicle in a double failure situation, by controlling the main brake device by a control unit so that the main brake device delivers a hydraulic pressure formed by the auxiliary brake device to wheel brakes if something is wrong with the main brake device and the auxiliary brake device. 
     Although exemplary embodiments of the present disclosure have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, and substitutions are possible, without departing from the idea and scope of the claimed invention. Therefore, exemplary embodiments of the present disclosure have been described for the sake of brevity and clarity. The scope of the technical idea of the present embodiments is not limited by the illustrations. Accordingly, one of ordinary skill would understand the scope of the claimed invention is not to be limited by the above explicitly described embodiments but by the claims and equivalents thereof.