Patents by Inventor Leland L. Howland

Leland L. Howland has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5168713
    Abstract: A method of operating a compartmentalized transport refrigeration system having first, second and third compartments respectively served by a host refrigeration unit and first and second remote refrigeration units. The method includes the steps of providing a first signal when either of the first and second remote refrigeration units is in a cooling cycle, cycling the host refrigeration unit between cooling and heating cycles to hold a selected set point temperature of a fresh load in the first compartment, in the absence of the first signal, and providing a predetermined null period between the heating and cooling cycles of the host unit when the first signal is present. In a preferred embodiment a prime mover for a refrigerant compressor is operable at a selected one of high and low speeds, with the method including the step of preventing high speed operation when any remote refrigeration unit is in a heating cycle.
    Type: Grant
    Filed: March 12, 1992
    Date of Patent: December 8, 1992
    Assignee: Thermo King Corporation
    Inventor: Leland L. Howland
  • Patent number: 5161383
    Abstract: A method of operating a transport refrigeration system having a refrigerant compressor driven by an internal combustion engine. Microprocessor based electrical control maintains the temperature of a conditioned space at a desired set point via heating, cooling and null cycles, with the engine being started and stopped, as required. During the engine starting process, a suction line modulation valve, if used, is closed, engine pre-heat time is selected, including using engine temperature to access a look-up table, and current draw is checked during pre-heat. Excessive current terminates pre-heat. Control diagnostics checks the voltage level on both sides of a refrigerant high pressure switch, before initiating engine cranking. Prior to stopping the engine, a control option initiates a heating cycle for a short time when null is being entered from a cooling cycle, to warm the evaporator and prevent premature starting of the engine.
    Type: Grant
    Filed: April 16, 1992
    Date of Patent: November 10, 1992
    Assignee: Thermo King Corporation
    Inventors: Jay L. Hanson, Leland L. Howland
  • Patent number: 5140826
    Abstract: A method of operating a transport refrigeration system having a refrigerant compressor driven by an internal combustion engine. Microprocessor based electrical control maintains the temperature of a conditioned space at a desired set point via heating, cooling and null cycles, with the engine being started and stopped, as required. During the engine starting process, a suction line modulation valve, if used, is closed, engine pre-heat time is selected, including using engine temperature to access a look-up table, and current draw is checked during pre-heat. Excessive current terminates pre-heat. Control diagnostics checks the voltage level on both sides of a refrigerant high pressure switch, before initiating engine cranking. Prior to stopping the engine, a control option initiates a heating cycle for a short time when null is being entered from a cooling cycle, to warm the evaporator and prevent premature starting of the engine.
    Type: Grant
    Filed: July 11, 1991
    Date of Patent: August 25, 1992
    Assignee: Thermo King Corporation
    Inventors: Jay L. Hanson, Leland L. Howland
  • Patent number: 5107686
    Abstract: A transport refrigeration system including host and remote refrigeration systems having local and remote evaporators, respectively, for respectively controlling the temperatures of first and second compartments via cooling and hot gas heating cycles. The host and remote refrigeration systems each have a plurality of controllable valves, including a controllable valve in their respective suction lines, and they each have a suction line to liquid line refrigerant by-pass lines, enabling either the host or remote evaporator to function as a condenser for the other, while by passing the normal condenser function, and further enabling either evaporator to control to a lower temperature than the other, as desired.
    Type: Grant
    Filed: January 28, 1991
    Date of Patent: April 28, 1992
    Assignee: Thermo King Corporation
    Inventor: Leland L. Howland
  • Patent number: 5105096
    Abstract: A transport refrigeration system including a refrigerant compressor which is alternatively driven by an internal combustion engine or an electric induction motor. The transport refrigeration system achieves and maintains a predetermined set point temperature in a served space by heating and cooling cycles. When additional heat is required during a heating cycle while the internal combustion engine is driving the compressor, capacitors are connected across the induction motor, to cause the motor to function as an induction generator and build up an output voltage. The output voltage is monitored, and when it is sufficient to sustain a load, resistors located to aid the heating cycle are connected to receive the output voltage.
    Type: Grant
    Filed: May 17, 1989
    Date of Patent: April 14, 1992
    Assignee: Thermo King Corporation
    Inventors: John E. Waldschmidt, Leland L. Howland
  • Patent number: 5065587
    Abstract: A compartmentalized transport refrigeration system having refrigeration control, and interconnected host and remote refrigeration units for respectively conditioning the air in front and rear compartments of a trailer. The trailer has front and rear doors for access to the front and rear compartments, respectively, and a door switch connected to the refrigeration control which modifies the operation of the refrigeration system when the front access door is opened. When the front access door is opened, the host refrigeration unit is operated in null and the remote refrigeration unit is cycled between heating and cooling modes. A door switch may also be provided for the second access door which modifies the operation of the transport refrigeration system by effectively turning the remote refrigeration unit off.
    Type: Grant
    Filed: January 28, 1991
    Date of Patent: November 19, 1991
    Assignee: Thermo King Corporation
    Inventors: Leland L. Howland, Jan M. Parker, Doyle G. Herrig, David A. Swanson
  • Patent number: 4932219
    Abstract: A transport refrigeration system having a compressor, condenser, receiver, and evaporator, for controlling the temperature of a served space via hot gas heating and cooling cycles. The receiver is selectively pressurized during a hot gas heating cycle, pressurizing the receiver at low ambient temperatures as sensed by compressor head pressure, and terminating or preventing receiver pressurization above a predetermined head pressure. This is useful for transport refrigeration systems which have a single compartment to condition, and it is even more useful in compartmentalized transport refrigeration systems having two or more compartments to condition.
    Type: Grant
    Filed: October 26, 1989
    Date of Patent: June 12, 1990
    Assignee: Thermo King Corporation
    Inventors: Leland L. Howland, Doyle G. Herrig
  • Patent number: 4920756
    Abstract: A transport refrigeration system having a dehumidifying mode. During the dehumidifying mode, a main or primary condenser is effectively removed from the active refrigerant circuit and an auxiliary or secondary condenser located in a conditioned air flow path performs the condensing function. This arrangement enables an evaporator in the air flow path to continue to cool and remove moisture from the conditioned air after a predetermined set point temperature has been reached, without a significant reduction in temperature of the conditioned air returned to a served space, as heat removed from the conditioned air by the evaporator is returned to the conditioned air by the secondary condenser.
    Type: Grant
    Filed: February 15, 1989
    Date of Patent: May 1, 1990
    Assignee: Thermo King Corporation
    Inventors: Leland L. Howland, David H. Taylor
  • Patent number: 4912940
    Abstract: A refrigerant evaporator assembly suitable for remote mounting to a ceiling of a trailer compartment having a served space to be conditioned. The evaporator assembly is modular, including an evaporator module, a cover module, and an evaporator blower module. The evaporator and cover modules cooperatively define a tubular housing having first and second open ends, with the blower module removably closing the second open end. A grille covers the first open end. The evaporator module includes a base member which functions as a support base for the evaporator module during assembly of the module and as a drain pan in the refrigerant evaporator assembly. The cover module functions as a support base for the evaporator coil when the evaporator assembly is mounted to the ceiling of a trailer compartment.
    Type: Grant
    Filed: May 15, 1989
    Date of Patent: April 3, 1990
    Assignee: Thermo King Corporation
    Inventors: Lowell M. Anderson, Leland L. Howland, Ambrose Tao
  • Patent number: 4903495
    Abstract: A transport refrigeration system, and method of operating same, in which a maximum operating pressure expansion valve and a secondary condenser are used to enhance hot gas heating cycles initiated to hold a predetermined temperature set point, and hot gas defrost cycles. The secondary condenser is disposed in an evaporator section of the refrigeration system, with hot discharge gas from a compressor being directed to the secondary condenser during heating and defrost cycles. A sufficient supply of refrigerant for heating and defrost cycles is ensured by injecting refrigerant from a receiver and condenser into an active heat cycle refrigerant circuit, when the active refrigerant is insufficient to build the pressure on the low pressure side of the refrigeration system to a value sufficient to close the maximum operating pressure expansion valve and the compressor suction pressure is less than the receiver/condenser pressure.
    Type: Grant
    Filed: February 15, 1989
    Date of Patent: February 27, 1990
    Assignee: Thermo King Corp.
    Inventors: Leland L. Howland, David H. Taylor, Cynthia J. Satterness
  • Patent number: 4896512
    Abstract: A compartmentalized transport refrigeration system including a refrigeration system having a compressor and first and second selectable refrigeration circuits normally associated with cooling and heating modes, respectively, a trailer having at least first and second compartments, a host evaporator, a condenser in the first refrigeration circuit, and at least one remote evaporator, with the evaporators each being associated with a trailer compartment. The second refrigeration circuit is selected when a remote evaporator requires heating, and when another evaporator requires cooling while a remote evaporator requires heating, refrigerant is returned to the compressor via the first refrigeration circuit and the evaporator requiring cooling, entering the first refrigeration circuit at a point which by-passes the normal condenser function, to cause the evaporator requiring heating to function as a condenser for the evaporator requiring cooling.
    Type: Grant
    Filed: January 25, 1989
    Date of Patent: January 30, 1990
    Assignee: Thermo King Corporation
    Inventor: Leland L. Howland
  • Patent number: 4878465
    Abstract: Electrical control apparatus for automatically starting a Diesel engine. The apparatus includes start, preheat and run relays which respectively control the energization of a starting solenoid, glow plugs, and a fuel solenoid. The energization of the start, preheat and run relays is controlled by a control module which drives the preheat relay as soon as the control module is energized. The glow plug preheat time is measured, and the run and start relays are respectively energized just prior to, and at the termination of the preheat time. Engine cranking time and speed are monitored, dropping the start and preheat relays when the engine starts, and also when the engine speed fails to reach certain thresholds within first and second predetermined periods of time. The run relay continues to energize an electrical circuit which includes an engine reset switch and a low oil pressure switch. The engine reset switch de-energizes the control module, and thus the run relay, in the event the engine fails to start.
    Type: Grant
    Filed: August 26, 1988
    Date of Patent: November 7, 1989
    Assignee: Thermo King Corporation
    Inventors: Jay L. Hanson, Leland L. Howland
  • Patent number: 4735055
    Abstract: A method of operating a transport refrigeration system having a six cylinder compressor and a prime mover operable at a selected one of low and high speeds, to control the temperature of a served space by cooling and hot gas heating modes. Below a set point temperature 100, system heating capacity is controlled at the low compressor speed by the step 127 of unloading compressor cylinders and the step 129 of reloading compressor cylinders. A temperature rise of the served space above a set point temperature 106 controls cooling capacity by a combination of alternative steps 135, 137, 139, 141, and 143 which may or may not change the number of loaded compressor cylinders, and may or may not change compressor speed, based upon two predetermined trigger events which relate to what the temperature of the served space does relative to time 136 and 142, a set point temperature 106, and a temperature 108 above set point which is normally associated with a change in compressor speed.
    Type: Grant
    Filed: June 15, 1987
    Date of Patent: April 5, 1988
    Assignee: Thermo King Corporation
    Inventors: David H. Taylor, Lee J. Erickson, Leland L. Howland
  • Patent number: 4720980
    Abstract: A method of enhancing the defrost and heating cycles of a transport refrigeration system for a straight truck, which refrigeration system includes a single refrigeration circuit selectively connectible to a compressor driven by the truck engine, or to a stand-by compressor driven by a motor connected to a stand-by source of electrical potential. The enhancement is achieved by slowly but continuously storing heat in an accumulator from the truck electrical system, or from the stand-by source of electrical potential, such that liquified refrigerant introduced into the accumulator during a defrost or heating cycle is immmediately vaporized. The slow but continuous rate of heat storage accumulates the requisite heat without unduly loading the truck electrical system or the truck engine.
    Type: Grant
    Filed: March 4, 1987
    Date of Patent: January 26, 1988
    Assignee: Thermo King Corporation
    Inventor: Leland L. Howland
  • Patent number: 4712383
    Abstract: A compartmentalized transport refrigeration system, and method of operating same, in which a host refrigeration unit controls the temperature of the air in a front compartment of a trailer, and a remote evaporator unit controls the temperature of the air in a rear compartment. In order to increase the heating capacity of the remote evaporator, the host's hot gas line is selectively controlled to enable all of the hot gas from the compressor to be directed to the remote evaporator when the host unit is in null. The host unit can only heat when the remote unit is in null. In order to increase the cooling capacity of the remote unit, the host's liquid line in selectively controlled to enable the liquid from the receiver to be all directed to the remote evaporator unit when the host unit is in null.
    Type: Grant
    Filed: April 9, 1987
    Date of Patent: December 15, 1987
    Assignee: Thermo King Corporation
    Inventors: Leland L. Howland, Jayaram Seshadri
  • Patent number: 4711095
    Abstract: A compartmentalized transport refrigeration system, and method of operating same, in which a host refrigeration unit controls the temperature of the air in a front compartment of a trailer, and a remote evaporator unit controls the temperature of the air in a rear compartment. In order to increase the heating and cooling capacity of the remote evaporator, the host unit is prevented from going into a heating mode in response to predetermined conditions, and more, or all in certain instances, of the discharge gas from the host compressor is made available for the remote evaporator.
    Type: Grant
    Filed: October 6, 1986
    Date of Patent: December 8, 1987
    Assignee: Thermo King Corporation
    Inventors: Leland L. Howland, Jayaram Seshadri
  • Patent number: 4706468
    Abstract: A compartmentalized transport refrigeration system, and method of operating same, in which a host refrigeration unit controls the temperature of the air in a front compartment of a trailer, and a remote evaporator unit controls the temperature of the air in a rear compartment. In order to increase the heating and cooling capacity of the remote evaportor, the host unit is prevented from going into a heating mode in response to predetermined conditions, and more, or all in certain instances, of the discharge gas from the host compressor is made available for the remote evaporator.
    Type: Grant
    Filed: April 9, 1987
    Date of Patent: November 17, 1987
    Assignee: Thermo King Corporation
    Inventors: Leland L. Howland, Jayaram Seshadri
  • Patent number: 4685306
    Abstract: A compartmentalized transport refrigeration system, and method of operating same, in which a host refrigeration unit controls the temperature of the air in a front compartment of a trailer, and a remote evaporator unit controls the temperature of the air in a rear compartment. In order to increase the heating capacity of the remote evaporator, the host's hot gas line is selectively controlled to enable all of the hot gas from the compressor to be directed to the remote evaporator when the host unit is in null. The host unit can only heat when the remote unit is in null. In order to increase the cooling capacity of the remote unit, the host's liquid line in selectively controlled to enable the liquid from the receiver to be all directed to the remote evaporator unit when the host unit is in null.
    Type: Grant
    Filed: October 6, 1986
    Date of Patent: August 11, 1987
    Assignee: Westinghouse Electric Corp.
    Inventors: Leland L. Howland, Jayaram Seshadri
  • Patent number: 4419866
    Abstract: A transport refrigeration unit powered by a two speed prime mover and having the capability of providing at least four modes of operation is controlled by an arrangement as shown in FIG. 2 which provides for operation in either a continuous cycle in which the prime mover runs continuously to provide the modes shown in FIG. 3 or, alternatively, operates in a start-stop cycle to provide the modes of operation shown in FIG. 4. The control in both of the cycles of operation provide for delays in the change of speed from low to high upon certain departures in temperature from one temperature band to another band which would normally call for high speed operation.
    Type: Grant
    Filed: June 9, 1982
    Date of Patent: December 13, 1983
    Assignee: Thermo King Corporation
    Inventor: Leland L. Howland
  • Patent number: D313569
    Type: Grant
    Filed: June 27, 1988
    Date of Patent: January 8, 1991
    Assignee: Thermo King Corporation
    Inventors: Peter B. Allard, Leland L. Howland, Jan H. Parker, David B. Ziegler